8,698 results
Search Results
2. Direct generation of high-valent iron-oxo species to eliminate oxytetracycline at circumneutral pH via paper mill sludge ash activating peroxymonosulfate.
- Author
-
Lin, Tingting, Zhou, Huajing, Zhao, Lingxiang, Liang, Sheng, Luo, Yongming, He, Liang, Shan, Shaoyun, Hu, Tianding, Liu, Zilian, and Du, Wentao
- Subjects
- *
PAPER mills , *PEROXYMONOSULFATE , *OXYTETRACYCLINE , *DENSITY functional theory , *CATALYTIC activity , *ARSENIC removal (Water purification) , *FORMYLATION - Abstract
[Display omitted] • Paper mill sludge ash (pm SA) was used as catalysts to activate PMS. • Aerobic calcination was conducive to the exposure/formation of octahedral FeIII. • The O O bond fracture was the root pathway for FeIV O production. • The release of solid calcium in pm SA could inhibit the active decay of FeIV O. • The pm SA could effectively degrade similar pollutants in near-neutral water. The excellent performance of high-valent iron-oxo species (FeIV O) in the degradation of pollutants by activating peroxymonosulfate (PMS) had attracted much attention. However, the generation and reaction mechanisms were still unclear. In this study, iron-rich paper mill sludge was used as a raw material for the first time to prepare iron-based catalysts with abundant octahedral FeIII sites (Fe oct III). The results showed that the highest content of Fe oct III was found in the paper mill sludge ash obtained by aerobic calcination at 800 °C (pm SA800), and the pm SA800 could exhibit excellent catalytic activity (0.4785 min−1) and stability during the oxytetracycline (OTC) degradation process. The characterization and density functional theory (DFT) calculations further indicated that the Fe oct III was the dominant active site for FeIV O production. PMS tended to be adsorbed on two adjacent Fe oct III sites to form a [Fe oct III-OSO 2 OO(H)-Fe oct III] complex with a two-site adsorption configuration. Subsequently, the O O and O H bonds in [Fe oct III-OSO 2 OO(H)-Fe oct III] broken by absorbing energy, generating FeIV O. It's worth noting that the Ca species of pm SA800 effectively stabilized the pH of the reaction solution, which ensured the stable and continuous production of FeIV O. This work provides a new idea and insight for preparing catalysts that could produce FeIV O active species. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Amorphous nanosphere self-supporting electrode based on filter paper for efficient water splitting.
- Author
-
Zhang, Yue, Zhang, Zhe, Zhang, Xuetao, Gao, Xinglong, Shang, Zhihui, Huang, Xuezhen, Guo, Enyan, Si, Conghui, Wei, Mingzhi, Lu, Qifang, and Han, Xiujun
- Subjects
- *
FILTER paper , *PHOTOCATHODES , *CARBON fibers , *COTTON fibers , *ELECTRODES , *DENSITY functional theory , *HYDROGEN evolution reactions , *OXYGEN evolution reactions - Abstract
Given its superior structure, the abundance of surface functional groups, and low cost, cotton fiber filtration paper can be used as the support for hydrogen evolution reaction (HER) and oxygen evolution reaction catalysts (OER) instead of copper foam (CF), nickel foam (NF), or carbon cloth (CC). Herein, the chemical plating method was used to create thin self-supporting electrodes based on cotton fiber filtration paper (FP). The Co-Ni-P amorphous nanospheres can be uniformly dispersed on the self-supporting FP due to its porous structure and oxygen functional groups. The Co-Ni-P/FP electrode has an overpotential as low as 125 mV for HER and 320 mV for OER at the current density of 10 mA cm−2. Additionally, according to density functional theory (DFT) calculations, the Co atom added to the Ni-P nanosphere can lead to considerably more charge accumulation around the Co and Ni active sites, which greatly encourages the HER and OER processes. The novel porous support, FP, provides a fresh way the preparation of self-supporting electrodes. [Display omitted] • Filter paper is used to prepare the self-supporting electrode as the substrate. • The preparation method is simple and the properties are stable. • Rich oxygen-containing functional groups of FP promote deposition and dispersion. • Explore the excellent electrochemical performance of amorphous Co-Ni-P/FP by DFT. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. A frugal machine-intelligent paper sensor for quantification of glucose through standalone desktop application: A computational and experimental approach.
- Author
-
Pal, Arijit, Biswas, Souvik, Chaudhury, Koel, and Das, Soumen
- Subjects
- *
ELECTRONIC band structure , *ELECTROCHEMICAL sensors , *DENSITY functional theory , *FRONTIER orbitals , *OXIDATION of glucose , *GLUCOSE analysis - Abstract
[Display omitted] • Catalytic properties of MoS 2 in presence of glucose has been studied using DFT. • Molecular level substrate-analyte interaction has been studied through NCI plot. • Mos 2 functionalized paper based electrochemical sensor for glucose has been developed. • The paper based electrochemical sensor shows good accuracy and selectivity. • The ML-driven smart app, GluQuantify, shows enhanced accuracy and resolution. A paper-based electrochemical sensor utilizing MoS 2 as sensing material is developed to quantitatively estimate glucose in a complex extracellular fluid matrix. The contribution of MoS 2 as sensing material is substantiated in the context of density functional theory formalism. The molecular modelling of MoS 2 and glucose interaction is elucidated through the theoretical estimation of non-covalent interactions and charge density difference plots. The charge transfer phenomenon during the oxidation of glucose molecule in electrochemical experiments is verified through electronic band structure analysis and frontier orbital theory. The electrochemical responses indicate that the sensor exhibits an average accuracy of nearly 96%, with a quantification limit of 100 nM. Furthermore, the chronoamperometric measurements highlight the superior sensitivity of the device in presence of various perturbing molecules. The obtained DPV responses were integrated with a robust machine learning-driven standalone app GluQuantify. This app precisely predicts the glucose concentrations in serum samples. The utilization of GluQuantify substantially elevates the overall accuracy of the sensing platform to 99% and automates the detection process. The application also enhances the resolution of the sensor to 0.01 µM, which mitigates the sensor resolution-related issues in manual estimation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Ultra-bright blue fluorescent nitrogen doped black phosphorus quantum dots for a visual detection of bilirubin on paper strip and cell imaging applications.
- Author
-
Pakapongpan, Saithip, Primpray, Vitsarut, Sirimak, Sukanya, Lunnoo, Thodsaphon, Moonlek, Chalisa, Phochakum, Kanchanok, and Jomphoak, Apichai
- Subjects
- *
FLUORESCENCE yield , *X-ray photoelectron spectroscopy , *CELL imaging , *DENSITY functional theory , *TRANSMISSION electron microscopy , *QUANTUM dots - Abstract
[Display omitted] • N-BPQD was synthesized through a solvothermal method using formamide as N source and solvent. • The N-BPQD exhibit a bright blue fluorescence with high quantum yield of 73.7%. • N-BPQD on fPAD was used as a visual fluorescent sensing platform for detection of bilirubin. • The fluorescent sensor shows high sensitivity and selectivity to bilirubin. • N-BPQD was a good fluorescent probe for cellular imaging. A facile top down producing approach for synthesis and doping of a nitrogen doped black phosphorus quantum dots (N-BPQD) in one-pot was developed by solvothermal method with formamide as a nitrogen source and solvent. The nitrogen atoms had introduced into BPQD structure and exhibit a bright blue photoluminescent with a high quantum yield of 73.7 %. The morphology and chemical structure of N-BPQD was characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. A fluorescent paper analysis device (fPAD) was applied in rapid and cost-effective detection of biomarker bilirubin with naked eyes. The fPAD sensor present a high selectivity, stability and sensitive response to bilirubin in a wide linear range of 10 to 150 µM with a limit of detection limit as 26 nM (S/N = 3) and limit of quantitation as 86 nM (S/N = 10). The principles-based density functional theory, calculations on doping and binding energy of N-BPQD were analyzed via the density functional theory (DFT) simulations. Moreover, N-BPQD showed extremely low cytotoxicity, which is a promising as a good fluorescent probe for stem cell imaging application. This work provide a new platform for diagnosis of jaundice disease. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Engineering the interfacial orientation of MoS2/Co9S8 bidirectional catalysts with highly exposed active sites for reversible Li-CO2 batteries.
- Author
-
Bingyi Lu, Biao Chen, Dashuai Wang, Chuang Li, Runhua Gao, Yingqi Liu, Rui Mao, Jinlong Yang, and Guangmin Zhou
- Subjects
- *
DENSITY functional theory , *CARBON paper , *CATALYSTS , *STORAGE batteries , *TRANSITION metals - Abstract
Sluggish CO2 reduction reaction (CO2RR) and evolution reaction (CO2ER) kinetics at cathodes seriously hamper the applications of Li-CO2 batteries, which have attracted vast attention as one kind of promising carbon-neutral technology. Two-dimensional transition metal dichalcogenides (TMDs) have shown great potential as the bidirectional catalysts for CO2 redox, but how to achieve a high exposure of dual active sites of TMDs with CO2RR/CO2ER activities remains a challenge. Herein, a bidirectional catalyst that vertically growing MoS2 on Co9S8 supported by carbon paper (V-MoS2/Co9S8@CP) has been designed with abundant edge as active sites for both CO2RR and CO2ER, improves the interfacial conductivity, and modulates the electron transportation pathway along the basal planes. As evidenced by the outstanding energy efficiency of 81.2% and ultra-small voltage gap of 0.68 V at 20 µA cm-2, Li-CO2 batteries with V-MoS2/Co9S8@CP show superior performance compared with horizontally growing MoS2 on Co9S8 (H-MoS2/Co9S8@CP), MoS2@CP, and Co9S8@CP. Density functional theory calculations help reveal the relationship between performance and structure and demonstrate the synergistic effect between MoS2 edge sites and Co9S8. This work provides an avenue to understand and realize rationally designed electronic contact of TMDs with specified crystal facets, but more importantly, provides a feasible guide for the design of high-performance cathodic catalyst materials in Li-CO2 batteries. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
7. Rapid detection of urokinase plasminogen activator using flexible paper-based graphene-gold platform
- Author
-
Ramakrishna Podila, Prakash Parajuli, and Bipin Sharma
- Subjects
Paper ,General Physics and Astronomy ,Metal Nanoparticles ,Biosensing Techniques ,Rapid detection ,General Biochemistry, Genetics and Molecular Biology ,Antibodies ,Metastasis ,Biomaterials ,Limit of Detection ,Neoplasms ,Sense (molecular biology) ,medicine ,Humans ,General Materials Science ,Density Functional Theory ,Immunoassay ,Chemistry ,Urokinase Plasminogen Activator ,Cancer ,General Chemistry ,Paper based ,Articles ,medicine.disease ,Urokinase-Type Plasminogen Activator ,Recombinant Proteins ,Cancer treatment ,Cancer research ,Graphite ,Gold ,Fetal bovine serum - Abstract
Many studies have shown that urokinase plasminogen activator (uPA) is causally involved in promoting cancer invasion and metastasis. Thus, monitoring uPA levels could be very useful in cancer diagnosis, identification of initial metastasis, and guiding cancer treatment. Here, the authors developed a novel and scalable uPA sensor based on a graphene-gold nanoparticle platform that uses fluorescence of quantum dots to rapidly (
- Published
- 2020
8. Incorporation of nickel single atoms into carbon paper as self-standing electrocatalyst for CO2 reduction
- Author
-
Sara Frank, Alberto Roldan, Simin Li, Troels Skrydstrup, Kim Daasbjerg, Nina Lock, Marcel Ceccato, Xin-Ming Hu, and Xiuyuan Lu
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,Electrocatalyst ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Nickel ,Adsorption ,chemistry ,General Materials Science ,Density functional theory ,0210 nano-technology ,Carbon - Abstract
The design of selective and efficient catalysts for electrochemical CO2 reduction is highly desirable yet still challenging, in particular, if the aim is to make them binder-free and self-standing. Here, we report a new and straightforward strategy to incorporate Ni single atoms into a commercially available carbon paper to prepare a self-standing electrode. This is accomplished by consecutive acid activation, adsorption of Ni2+ ions, and pyrolysis steps. Structural characterizations and calculations based on density functional theory consistently suggest that the Ni single atoms are coordinated with three N and one S atoms on the carbon paper. When used for CO2 electroreduction, the electrode exhibits an optimal selectivity (91%), activity (3.4 mA cm-2), and stability (at least 14 h) for CO production in water at an overpotential of 660 mV. This report may inspire the design and incorporation of single atoms of various metal types into carbon papers, or other kinds of carbon substrates, for a wide range of electrocatalytic processes. This journal is
- Published
- 2021
9. Photoelectrochemical and photocatalytic detoxification of Cr(VI) to Cr(III) over terpyridine-derivatized Au nanoparticles on carbon paper and indium-tin-oxide electrodes.
- Author
-
Yi, Jae Moon, Kim, Tae Jun, Park, So Jeong, Hong, Sung-Min, Kang, Jun-Gill, Rhee, Choong Kyun, Kim, Jongwon, and Sohn, Youngku
- Subjects
- *
CARBON paper , *PHOTOCATHODES , *NANOPARTICLES , *DENSITY functional theory , *HEXAVALENT chromium , *CYCLIC voltammetry - Abstract
• 2,2′:6′,2′'-terpyridine-4′-thiol (STpy) functionalization on Au NP--carbon paper and ITO. • DFT for geometry optimization and the electronic energy state calculation. • PEC and photocatalytic detoxification of Cr(VI) by cyclic voltammetry. • Cr(VI) reduction significantly enhanced upon STpy functionalization. • XPS confirmed Cr(VI) reduction on the surface of CP-AuNP-STpy. Detoxification of hexavalent chromium (Cr(VI)) in the environment and development of corresponding new materials and detoxification protocols have actively been studied and applied. Herein, 2,2′:6′,2′'-terpyridine-4′-thiol (STpy) was functionalized on Au nanoparticle (NP)-loaded carbon paper (CP) and indium-tin-oxide (ITO) electrodes (CP-AuNP and ITO-AuNP, respectively), and the photoelectrochemical (PEC) and photocatalytic detoxification of Cr(VI) using the resulting electrodes was investigated by cyclic voltammetry. Density functional theory at the B3LYP/6-31G level was used for geometry optimization, and the electronic energy state calculation was conducted at the TD-SCF/DFT/B3LYP level. For bare CP, ITO, and STpy-modified AuNP electrodes, the reduction potentials of Cr(VI) were around + 0.3, −0.2 V, and + 0.5 V (vs. Ag/AgCl), respectively. The PEC and photocatalytic Cr(VI) reduction performance of CP-AuNP was significantly improved upon STpy functionalization. Thus, these newly developed functionalized systems can provide very useful information for further improving the detoxification performances for various hazardous metals. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Paper: In-situ high-pressure Raman scattering and ab-initio studies in Cu2Sb up to 45 GPa
- Author
-
Daniela Menegon Trichês, Marta Silva dos Santos Gusmao, Alain Polian, S. Michielon de Souza, J.C. de Lima, Puspitapallab Chaudhuri, Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Sorbonne Université (SU)
- Subjects
In situ ,[PHYS]Physics [physics] ,Materials science ,Phonon ,Mechanical Engineering ,Metals and Alloys ,Ab initio ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,Condensed Matter::Materials Science ,Tetragonal crystal system ,symbols.namesake ,Mechanics of Materials ,High pressure ,Materials Chemistry ,symbols ,Density functional theory ,0210 nano-technology ,Raman spectroscopy ,Raman scattering ,ComputingMilieux_MISCELLANEOUS - Abstract
The influence of pressure on the optical properties of nanostructured tetragonal Cu2Sb has been investigated jointly by experimental Raman spectroscopy (RS) and theoretical first-principles calculation based on density functional theory (DFT) varying pressure from zero (ambient condition) to 45 GPa. The DFT determined pressure dependence of the Raman active modes and the mode-Gruneisen parameters for each Raman mode are found to be in excellent agreement with those experimentally determined. Comparison of the pressure evolution of the experimental Raman data with those of DFT has allowed us to make the proper assignment of optical phonon modes.
- Published
- 2020
11. Neutron total cross section calculation within the framework of quasi-harmonic approximation:Paper
- Author
-
E. B. Klinkby and Xiao Xiao Cai
- Subjects
Physics ,Neutron transport ,Quasi-harmonic approximation ,010308 nuclear & particles physics ,Neutron diffraction ,General Physics and Astronomy ,Neutron scattering ,01 natural sciences ,Neutron cross section ,Computational physics ,Cross section (physics) ,Vibrational density of states ,0103 physical sciences ,Density functional theory ,Neutron ,Nuclear cross section ,010306 general physics - Abstract
The accuracy of neutron scattering cross sections is the gauge for the realistic outcome of a neutron transport simulation. To improve the traditional harmonic physics model used in such simulations, we revisit the slow neutron transport theory in crystalline materials and aim to develop a unified model that has good performance for neutron transport problems in crystals in a wide range of temperatures and pressures. The quasi-harmonic approximation (QHA) correlates phonon evolution explicitly with unit cell volume. Therefore, it is capable of evaluating a variety of material properties at finite temperatures. In this work, we show numerically that it is a very effective tool for our application as well. Within the framework of QHA, we calculate the temperature dependent characteristics of phonons in three elemental crystals, namely Be, Mg and Al. Based on the obtained results, our calculated neutron total cross sections agree closely with experimental transmission cross sections in a large temperature range below the melting point. We show that as the harmonic cross section model ignores the effects of phonon softening in these crystals, it underestimates the total inelastic cross sections at high temperatures. In the case of Al, we observe that such underestimation is up to 7% at room temperature. In addition, we study the phonon–phonon scatterings in Al. We observe that the cross section is insensitive to the finite phonon lifetimes even at 800 K.
- Published
- 2017
12. Triazole-based pyrene-sugar analogues for selective detection of picric acid in water medium and paper strips.
- Author
-
Dey, Biman, Pahari, Pallab, Sahoo, Suban K, and Kumar Atta, Ananta
- Subjects
- *
PICRIC acid , *FLUORESCENCE quenching , *DENSITY functional theory , *CHARGE transfer - Abstract
[Display omitted] • Carbohydrate-based fluorometric sensors 1 and 2 have been used to detect picric acid in the aqueous medium. • The detection limits of 1 and 2 for PA were calculated to be 0.094 µM and 0.013 µM, respectively. • The DFT-supported charge transfer and µ-µ interactions explained the fluorescence quenching mechanism. • The sugar moiety plays a role in developing interaction between the sensor and PA in aqueous medium. • Both the sensors were used as naked-eye colorimetric sensors for PA in the test trips. Triazole-linked pyrene-appended inexpensive sensors 1 and 2 were synthesized from carbohydrates to instantly recognize picric acid (PA) based on a charge-transfer mechanism in the semi-water medium. Both sensors showed good selectivity and sensitivity towards PA over a wide variation of nitroaromatics in the absorbance and fluorescence methods. Moreover, sensors 1 and 2 were used for quick finding of picric acids using test strips. Interestingly, it was found that the sensitivity of 2 (LOD: 0.012 µM) is higher than 1 (LOD: 0.093 µM) might be explained by the close intramolecular space of the triazole/sugar residue and pyrene in sensor 2. The fluorescence quenching and structural features of the complexes (1-PA, 2-PA) were supported by density functional theory (DFT) calculations and spectroscopic studies. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. Machine learning based urinary pH sensing using polyaniline deposited paper device and integration of smart web app interface: Theory to application.
- Author
-
Biswas, Souvik, Pal, Arijit, Chakraborty, Pratip, Chaudhury, Koel, and Das, Soumen
- Subjects
- *
WEB-based user interfaces , *SMART devices , *POLYANILINES , *MACHINE learning , *MACHINE theory , *ELECTRON transport , *LOCAL area networks , *STANDARD deviations - Abstract
The present study employs density functional theory-based first principle calculation to investigate the electron transport properties of polyaniline following exposure to acidic and alkaline pH. In-situ deposited polyaniline-based paper device maintains emeraldine salt form while it is exposed to acidic pH and converts to emeraldine base when it is subjected to alkaline pH solutions. These structural changes at acidic and alkaline pH are validated experimentally by Raman spectra. Furthermore, the Raman spectra computed from density functional theory are validated with the experimental spectra. The changes in the theoretical energy band gap of polyaniline obtained from first principle calculations were correlated with the changes in the experimental impedimetric response of the sensor after exposure to acidic and alkaline solutions. Finally, the impedimetric responses were used to predict urine pH through a machine learning based smart and interactive web application. Different machine learning based regression models were implemented to acquire the best possible outcome. Gradient Boosting Regressor with least square loss model was selected as it showed lowest mean square, mean absolute, and root mean square error than other models. The smart sensing platform successfully predicts the unknown pH of urine samples with an average accuracy of more than 98%. The locally deployed smart web app can be accessed within a local area network by the end-user, which holds promise towards effective detection of urinary pH. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
14. A comprehensive analysis of the history of DFT based on the bibliometric method RPYS
- Author
-
Haunschild, Robin, Barth, Andreas, and French, Bernie
- Published
- 2019
- Full Text
- View/download PDF
15. The effect of oxidative and paper degradation impurities on partial discharge characteristics of hexadecane.
- Author
-
Bolliger, Dominique, Pilania, Ghanshyam, and Boggs, Steven
- Subjects
- *
PARTIAL discharges , *ALKANES , *ELECTRODES , *ALTERNATING currents , *IP networks , *DENSITY functional theory , *DIELECTRICS - Abstract
Partial discharge (PD) characteristics of hexadecane were studied in a needle-plane electrode geometry under AC field with a tungsten needle of 20 μm tip radius. PD experiments were conducted on samples containing known concentrations of oil/paper degradation compounds. Partial discharge inception voltage (PDIV), streamer repetition rates, and phase resolved PD (PRPD) patterns were acquired. Ionization potentials (IP) and electron affinities (EA) of hexadecane and a selection of additives were calculated with density functional theory (DFT) and correlated to PD characteristics. IP did not have a significant effect on the number of streamers initiated as most additives had higher IP relative to hexadecane. The presence of electronegative oxygen changes substantially the PD characteristics and, for most additives, increases the number of positive and negative streamers initiated. The greatest changes in PD characteristics, a reduced number of negative streamers, was observed for compounds with large electron capture cross section, even those with negative EA. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
16. An Effective Method for Substance Detection Using the Broad Spectrum THz Signal: A "Terahertz Nose".
- Author
-
Trofimov, Vyacheslav A. and Varentsova, Svetlana A.
- Subjects
TIME-dependent density functional theory ,ABSORPTION ,PAPER napkins ,BROADBAND communication systems ,DENSITY functional theory - Abstract
We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
17. Terahertz Time Domain Spectroscopy of Transformer Insulation Paper after Thermal Aging Intervals.
- Author
-
Wang, Liang, Tang, Chao, Zhu, Shiping, and Zhou, Shengling
- Subjects
INSULATING materials ,DENSITY functional theory ,MOLECULAR dynamics ,POLYMERIZATION ,REFRACTIVE index - Abstract
An accelerated thermal aging process was used to simulate the condition of paper insulation in transformer oil-paper systems. Optical parameters of the insulation paper after various aging intervals were analyzed with terahertz time-domain spectroscopy (THz-TDS) over the range 0.1~1.8 THz. The result shows that the paper had seven absorption peaks at 0.19, 0.49, 0.82, 1.19, 1.43, 1.53, and 1.74 THz, and density functional theory of B3LYP/6-311G+ (d, p) was used to simulate the molecular dynamics of the repeating component (cellobiose) of the cellulose paper. Theoretical spectra were consistent with experiment, which had absorption peaks at 0.18, 0.82, 1.47, and 1.53 THz in the same frequency range. At the same time, the paper samples after various aging intervals had different refractive indexes, and least squares fitting revealed a linear relationship between the degree of polymerization and the refractive index of the paper. Hence, this paper demonstrates that THz-TDS could be used to analyze the aging condition of transformer insulation paper and provides the theoretical and experimental basis for detection. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
18. Topic modeling in density functional theory on citations of condensed matter electronic structure packages.
- Author
-
Dumaz, Marie, Romero-Bohórquez, Camila, Adjeroh, Donald, and Romero, Aldo H.
- Subjects
DENSITY functional theory ,CONDENSED matter ,ELECTRONIC packaging ,CLUSTER analysis (Statistics) - Abstract
With an increasing number of new scientific papers being released, it becomes harder for researchers to be aware of recent articles in their field of study. Accurately classifying papers is a first step in the direction of personalized catering and easy access to research of interest. The field of Density Functional Theory (DFT) in particular is a good example of a methodology used in very different studies, and interconnected disciplines, which has a very strong community publishing many research articles. We devise a new unsupervised method for classifying publications, based on topic modeling, and use a DFT-related selection of documents as a use case. We first create topics from word analysis and clustering of the abstracts from the publications, then attribute each publication/paper to a topic based on word similarity. We then make interesting observations by analyzing connections between the topics and publishers, journals, country or year of publication. The proposed approach is general, and can be applied to analyze publication and citation trends in other areas of study, beyond the field of Density Function Theory. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
19. Monodisperse Manganese‐Vanadium‐Oxo Clusters with Extraordinary Lithium Storage.
- Author
-
Tang, Wensi, Qiu, Tianyu, Hu, Zhiyuan, Li, Yingqi, Yao, Ruiqi, Wang, Yonghui, Lang, Xingyou, Tan, Huaqiao, Li, Yangguang, and Jiang, Qing
- Subjects
LITHIUM-ion batteries ,ENERGY storage ,DENSITY functional theory ,ELECTRIC conductivity ,SURFACE energy - Abstract
Although possessing well‐defined nanostructures and excellent multi‐electron redox properties, polyoxometalate clusters have poor intrinsic electrical conductivity and are prone to aggregation due to large surface energy, which makes them difficult to be fully utilized when applying as electrode materials for lithium‐ion batteries. In this paper, monodisperse K7MnV13O38 (MnV13) clusters are achieved by rationally utilizing nano‐sized high conductive carbon dots (CDs) as stabilizers. Benefiting from the fully exposed redox sites of MnV13 clusters (high utilization rate) and sufficient interfaces with carbon dots (extra interfacial energy storage), the optimized MnV13/10CDs anode delivers a high discharge capacity up to 1348 mAh g−1 at a current density of 0.1 A g−1 and exhibits superb rate/cycling capabilities. Density functional theory (DFT) calculations verify that ionic archway channels are formed between MnV13 and CDs, eliminating the bandgap and greatly improving the electron/ion conductivity of MnV13 and CDs. This paper paves a brand‐new way for synthesis of monodisperse clusters and maximization of extra interfacial energy storage. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Paper: In-situ high-pressure Raman scattering and ab-initio studies in Cu2Sb up to 45 GPa.
- Author
-
Michielon de Souza, S., Trichês, D.M., Gusmão, M.S., Chaudhuri, P., Polian, A., and de Lima, J.C.
- Subjects
- *
RAMAN scattering , *RAMAN effect , *DENSITY functional theory , *RAMAN spectroscopy , *OPTICAL properties , *COMPRESSIBILITY - Abstract
The influence of pressure on the optical properties of nanostructured tetragonal Cu 2 Sb has been investigated jointly by experimental Raman spectroscopy (RS) and theoretical first-principles calculation based on density functional theory (DFT) varying pressure from zero (ambient condition) to 45 GPa. The DFT determined pressure dependence of the Raman active modes and the mode-Grüneisen parameters for each Raman mode are found to be in excellent agreement with those experimentally determined. Comparison of the pressure evolution of the experimental Raman data with those of DFT has allowed us to make the proper assignment of optical phonon modes. Image 1 • The Raman modes of the Cu 2 Sb were observed under high-pressures conditions. • The high-pressure in-situ data were supported by ab initio calculations. • The compressibility parameter of the Cu2Sb were obtained. • In-situ high-pressure Raman scattering and ab-initio studies in Cu2Sb up to 45 GPa. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
21. Unlocking the power of lithium trifluoride, LiMF3 (M = Mn, Co, Fe, Ni, and V), materials through DFT: a paradigm shift in electrode candidates for high-performance Li-ion batteries.
- Author
-
Yousefi-Mashhour, Hatef, Hassani, Samin, Safaeipour, Sepideh, Shahpouri, Elham, Kalantarian, Mohammad Mahdi, and Namiranian, Afshin
- Abstract
In this paper, we explore the potential of LiMF
3 (Lithium Metal Trifluoride) materials as electrode candidates by using density functional theory (DFT) calculations. We investigate their structural, electrochemical, and electrical properties and compare them with each other and some way with the most popular Li electrode materials. The structural properties of this kind of materials are interesting due to their 3D framework and somehow their openness of the diffusion channels, causing facile Li diffusion through the structure. We find that LiMnF3 has the best properties among the LiMF3 materials, with high structural stability (endurance of the lattice after Li ion extraction), low band-gap, suitable cell voltage, and high electrical rate-capability. LiMnF3 is especially favorable due to its environmental and toxicity advantages. After that, LiCoF3 shows appropriate properties. We also discuss the advantages and disadvantages of the other LiMF3 materials, namely LiNiF3 , LiVF3 , and LiFeF3 , which they are also considerable electrodes. The voltage of the materials estimated to be 2, 2.6, 2.6, 3.4, and 3.1 V for M = Co, Fe, Ni, Mn, and V, respectively. This study provides a comprehensive evaluation of LiMF3 materials and suggests that they are promising candidates as Li-ion battery electrodes. This paper opens a new landscape for future investigations about these promising intercalation electrode materials. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
22. The Synergy between Nuclear Magnetic Resonance and Density Functional Theory Calculations.
- Author
-
Hansen, Poul Erik
- Subjects
NUCLEAR magnetic resonance ,DENSITY functional theory ,IONIC structure ,CHEMICAL bond lengths ,CHEMICAL shift (Nuclear magnetic resonance) ,TAUTOMERISM ,NUCLEAR magnetic resonance spectroscopy - Abstract
This paper deals with the synergy between Nuclear Magnetic Resonance (NMR) spectroscopic investigations and DFT calculations, mainly of NMR parameters. Both the liquid and the solid states are discussed here. This text is a mix of published results supplemented with new findings. This paper deals with examples in which useful results could not have been obtained without combining NMR measurements and DFT calculations. Examples of such cases are tautomeric systems in which NMR data are calculated for the tautomers; hydrogen-bonded systems in which better XH bond lengths can be determined; cage compounds for which assignment cannot be made based on NMR data alone; revison of already published structures; ionic compounds for which reference data are not available; assignment of solid-state spectra and crystal forms; and the creation of libraries for biological molecules. In addition to these literature cases, a revision of a cage structure and substituent effects on pyrroles is also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
23. Structural investigation of the complexation between vitamin B12 and per- and polyfluoroalkyl substances: Insights into degradation using density functional theory.
- Author
-
Koval AM, Jenness GR, and Shukla MK
- Subjects
- Environmental Pollutants chemistry, Environmental Restoration and Remediation methods, Alkanesulfonic Acids chemistry, Vitamin B 12 chemistry, Vitamin B 12 analogs & derivatives, Fluorocarbons chemistry, Density Functional Theory
- Abstract
Environmental remediation of per- and polyfluoroalkyl substances (PFAS) has become a significant research topic in recent years due to the fact that these materials are omnipresent, resistant to degradation and thus environmentally persistent. Unfortunately, they have also been shown to cause health concerns. PFAS are widely used in industrial applications and consumer products. Vitamin B12 (B12) has been identified as being catalytically active towards a variety of halogenated compounds such as PFAS. It has also been shown to be effective when using sulfide as a reducing agent for B12. This is promising as sulfide is readily available in the environment. However, there are many unknowns with respect to PFAS interactions with B12. These include the reaction mechanism and B12's specificity for PFAS with certain functionalization(s). In order to understand the specificity of B12 towards branched PFAS, we examined the atomistic interactions between B12 and eight different PFAS molecules using Density Functional Theory (B3LYP/cc-pVDZ). The PFAS test set included linear PFAS and their branched analogs, carboxylic acid and sulfonic acid headgroups, and aromatic and non-aromatic cyclic structures. Conformational analyses were carried out to determine the lowest energy configurations. This analysis showed that small chain PFAS such as perfluorobutanoic acid interact with the cobalt center of B12. Bulkier PFAS prefer to interact with the amine and carbonyl groups on the sidechains of the B12 ring system. Furthermore, computed complexation energies determined that, in general, branched PFAS (e.g. perfluoro-5-methylheptane sulfonic acid) interact more strongly than linear molecules (e.g. perfluorooctanesulfonic acid). Our results indicate that it may be possible to alter the interactions between B12 and PFAS by synthetically modifying the sidechains of the ring structure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)
- Published
- 2024
- Full Text
- View/download PDF
24. Mechanical and thermoelectric properties of ZrX 2 and HfX 2 (X = S and Se) from Van der Waals density-functional theory.
- Author
-
Ferahtia S, Benyettou S, Saib S, Bouarissa N, and Ouail K
- Subjects
- Thermal Conductivity, Selenium chemistry, Electric Conductivity, Models, Molecular, Temperature, Sulfur chemistry, Mechanical Phenomena, Density Functional Theory
- Abstract
The structural, mechanical, and thermoelectric characteristics of layered transition metal dichalcogenides MX
2 (M = Zr, Hf; X = S, Se) have been studied using density functional theory along with van der Waals correction. The exchange-correlation functional, enhanced with corrections for van der Waals interactions, has been evaluated for the hexagonal bulk structures of these materials. The analysis of elastic properties reveals that these compounds exhibit brittleness at zero pressure and conform to Born's criteria for mechanical stability. Examination of elastic constants and moduli suggests that the compounds possess reasonable machinability, moderate hardness, and anisotropy in terms of sound velocity. Transport properties, including the Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor, have been computed using the semi-classical Boltzmann theory implemented in the BoltzTraP code. All investigated compounds exhibit excellent thermoelectric performance at high temperatures. This result suggests that our compounds are highly promising candidate for practical utilization in the thermoelectric scope., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
25. Structural characterization and keto-enol tautomerization of 4-substituted pyrazolone derivatives with DFT approach.
- Author
-
Eryilmaz S and Bagdatli E
- Subjects
- Molecular Structure, Spectroscopy, Fourier Transform Infrared methods, Thermodynamics, Molecular Conformation, Magnetic Resonance Spectroscopy, Pyrazolones chemistry, Models, Molecular, Density Functional Theory
- Abstract
The synthesis of two pyrazolone derivative compounds, PYR-I(4-Acetyl-1-(4-chlorophenyl)-3-isopropyl-1H-pyrazol-5(4H)-one) and PYR-II1-(4-Chlorophenyl))-3-isopropyl-5-oxo-4,5-5-dihydro-1H-pyrazole-4-carbaldehyde, their characterization by FT-IR, NMR, UV-Vis and GC-MS techniques, and the evaluation of the keto-enol tautomerization process of the structures along with the DFT approach and spectral data were reported in this paper. Spectral findings indicated that PYR-I was stable at the keto state. The IR spectrum recorded in solid form showed that the PYR-II structure was stable in the enol state, while the NMR spectrum in the solution medium showed that it was stable in the keto state. DFT-based analyses were realized with the B3LYP hybrid functional and the 6-311++G(d,p) basis set. The modelled keto, transition and enol state molecular geometries of structures were optimized in the gas phase and different solvent media and the total energy and dipole moment values were investigated at the specified theoretical level. The possible keto-enol tautomerism mechanism of the structures was evaluated through some thermodynamic parameters such as the difference in free Gibbs energy (ΔG), enthalpy (ΔH), entropy (ΔS), and predictive tautomeric equilibrium constants (K
eq ), acidity constants (pKa ) and percentages of tautomers at 298.15 K and 1 atm pressure. The results of these analyses based on the DFT approach indicated that the keto-enol tautomer equilibrium heavily favours the keto form for PYR-I and the enol form for PYR-II in all cases. Moreover, natural bond orbital (NBO) analysis was performed for the tautomers, and the chemical reactivity profiles of the most stable tautomers were examined with the values of frontier molecular orbital energy and some reactivity descriptors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
26. Density functional theory and enzyme studies support interactions between angiotensin receptor blockers and angiotensin converting enzyme-2: Relevance to coronavirus 2019.
- Author
-
Apostolopoulos V, Georgiou N, Tzeli D, Mavromoustakos T, Moore GJ, Kelaidonis K, Matsoukas MT, Tsiodras S, Swiderski J, Kate Gadanec L, Zulli A, Chasapis CT, and Matsoukas JM
- Subjects
- Humans, Biphenyl Compounds pharmacology, Biphenyl Compounds chemistry, Antiviral Agents pharmacology, Antiviral Agents chemistry, Antiviral Agents chemical synthesis, COVID-19 virology, Structure-Activity Relationship, Molecular Structure, Benzimidazoles pharmacology, Benzimidazoles chemistry, Tetrazoles pharmacology, Tetrazoles chemistry, Tetrazoles chemical synthesis, Angiotensin-Converting Enzyme Inhibitors pharmacology, Angiotensin-Converting Enzyme Inhibitors chemistry, Angiotensin-Converting Enzyme Inhibitors metabolism, COVID-19 Drug Treatment, Angiotensin-Converting Enzyme 2 metabolism, Angiotensin-Converting Enzyme 2 chemistry, SARS-CoV-2 drug effects, SARS-CoV-2 enzymology, Density Functional Theory, Angiotensin Receptor Antagonists pharmacology, Angiotensin Receptor Antagonists chemistry
- Abstract
The binding affinities and interactions between eight drug candidates, both commercially available (candesartan; losartan; losartan carboxylic acid; nirmatrelvir; telmisartan) and newly synthesized benzimidazole-N-biphenyltetrazole (ACC519T), benzimidazole bis-N,N'-biphenyltetrazole (ACC519T(2) and 4-butyl-N,N-bis([2-(2H-tetrazol-5-yl)biphenyl-4-yl]) methyl (BV6), and the active site of angiotensin-converting enzyme-2 (ACE2) were evaluated for their potential as inhibitors against SARS-CoV-2 and regulators of ACE2 function through Density Functional Theory methodology and enzyme activity assays, respectively. Notably, telmisartan and ACC519T(2) exhibited pronounced binding affinities, forming strong interactions with ACE2's active center, favorably accepting proton from the guanidinium group of arginine273. The ordering of candidates by binding affinity and reactivity descriptors, emerged as telmisartan > ACC519T(2) > candesartan > ACC519T > losartan carboxylic acid > BV6 > losartan > nirmatrelvir. Proton transfers among the active center amino acids revealed their interconnectedness, highlighting a chain-like proton transfer involving tyrosine, phenylalanine, and histidine. Furthermore, these candidates revealed their potential antiviral abilities by influencing proton transfer within the ACE2 active site. Furthermore, through an in vitro pharmacological assays we determined that candesartan and the BV6 derivative, 4-butyl-N,N0-bis[20-2Htetrazol-5-yl)bipheyl-4-yl]methyl)imidazolium bromide (BV6(K
+ )2 ) also contain the capacity to increase ACE2 functional activity. This comprehensive analysis collectively underscores the promise of these compounds as potential therapeutic agents against SARS-CoV-2 by targeting crucial protein interactions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
27. Efficient catalytic oxidation of formaldehyde by defective g-C 3 N 4 -anchored single-atom Pt: A DFT study.
- Author
-
Zheng Z, Zhang C, Li J, Fang D, Tan P, Fang Q, and Chen G
- Subjects
- Catalysis, Nitrogen Compounds chemistry, Molecular Dynamics Simulation, Oxygen chemistry, Graphite, Formaldehyde chemistry, Oxidation-Reduction, Density Functional Theory, Platinum chemistry
- Abstract
Indoor volatile formaldehyde is a serious health hazard. The development of low-temperature and efficient nonhomogeneous oxidation catalysts is crucial for protecting human health and the environment but is also quite challenging. Single-atom catalysts (SACs) with active centers and coordination environments that are precisely tunable at the atomic level exhibit excellent catalytic activity in many catalytic fields. Among two-dimensional materials, the nonmagnetic monolayer material g-C
3 N4 may be a good platform for loading single atoms. In this study, the effect of nitrogen defect formation on the charge distribution of g-C3 N4 is discussed in detail using density functional theory (DFT) calculations. The effect of nitrogen defects on the activated molecular oxygen of Pt/C3 N4 was systematically revealed by DFT calculations in combination with molecular orbital theory. Two typical reaction mechanisms for the catalytic oxidation of formaldehyde were proposed based on the Eley-Rideal (E-R) mechanism. Pt/C3 N4 -V3N was more advantageous for path 1, as determined by the activation energy barrier of the rate-determining step and product desorption. Finally, the active centers and chemical structures of Pt/C3 N4 and Pt/C3 N4 -V3N were verified to have good stability at 375 K by determination of the migration energy barriers and ab initio molecular dynamics simulations. Therefore, the formation of N defects can effectively anchor single-atom Pt and provide additional active sites, which in turn activate molecular oxygen to efficiently catalyze the oxidation of formaldehyde. This study provides a better understanding of the mechanism of formaldehyde oxidation by single-atom Pt catalysts and a new idea for the development of Pt as well as other metal-based single-atom oxidation catalysts., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Cheng Zhang reports was provided by National Natural Science Foundation of China. Cheng Zhang reports a relationship with Huazhong University of Science and Technology that includes: non-financial support. nothing If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
28. Bonding, Aromaticity and Isomerization of Furfuraldehyde through Off‐Nucleus Isotropic Magnetic Shielding
- Author
-
Muntadar Abd Al-Barri Hussain Al-Yassiri
- Subjects
Full Paper ,chemical bonding ,furfuraldehyde ,Aromaticity ,General Chemistry ,aromaticity ,Full Papers ,chemistry.chemical_compound ,Crystallography ,Chemistry ,Atomic orbital ,Chemical bond ,chemistry ,Furan ,Order (group theory) ,Density functional theory ,off-nucleus isotropic shielding ,Isomerization ,QD1-999 ,Basis set ,nucleus-independent chemical shift NICS - Abstract
Off‐nucleus isotropic magnetic shielding (σ iso(r)) and multi‐points nucleus independent chemical shift (NICS(0‐2 Å)) index were utilized to find the impacts of the isomerization of gas‐phase furfuraldehyde (FD) on bonding and aromaticity of FD. Multidimensional (1D to 3D) grids of ghost atoms (bqs) were used as local magnetic probes to evaluate σ iso(r) through gauge‐including atomic orbitals (GIAO) at density functional theory (DFT) and B3LYP functional/6‐311+G(d,p) basis set level of theory. 1D σ iso(r) responses along each bond of FD were examined. Also, a σ iso(r) 2D‐scan was performed to obtain σ iso(r) behavior at vertical heights of 0–1 Å above the FD plane in its cis, transition state (TS) and trans forms. New techniques for evaluating 2D σ iso(r) cross‐sections are also included. Our findings showed that bonds in cyclic and acyclic parts of FD are dissimilar. Unlike the C−O bond of furanyl, the C=O bond of the formyl group is magnetically different. C−C and C−H bonds in furanyl are found similar to those in aromatic rings. A unique σ iso(r) trend was observed for the C2−C6 bond during FD isomerization. Based on NICS(0‐2 Å) values, the degree of aromaticity follows the order of cis FD, Isomerization, bonding and aromaticity of furfuraldehyde (FD) have been evaluated through multidimensional off‐nucleus isotropic magnetic shieldings at the DFT‐GIAO/6‐311+G(d,p) level of theory. Significant changes in magnetic behaviour were observed mainly for the rotated C−C bond that linked the furanyl with the formyl group. Other C−C bonds in furanyl behave like C−C bonds of aromatic rings. The transition state FD has more aromaticity than the cis or trans isomers.
- Published
- 2021
29. Seven‐Membered Cyclic Potassium Diamidoalumanyls
- Author
-
Mary F. Mahon, Han-Ying Liu, Nasir A. Rajabi, Michael S. Hill, Ryan J. Schwamm, and Claire L. McMullin
- Subjects
chemistry.chemical_classification ,coordination modes ,Full Paper ,Chemistry ,Potassium ,aluminium ,Iodide ,Organic Chemistry ,chemistry.chemical_element ,Order (ring theory) ,Hot Paper ,General Chemistry ,Full Papers ,main group chemistry ,Potassium Cation ,metal-metal interactions ,Toluene ,Medicinal chemistry ,Catalysis ,chemistry.chemical_compound ,Nucleophile ,Moiety ,Density functional theory - Abstract
The seven‐membered cyclic potassium alumanyl species, [{SiNMes}AlK]2 [{SiNMes}={CH2SiMe2N(Mes)}2; Mes=2,4,6‐Me3C6H2], which adopts a dimeric structure supported by flanking K‐aryl interactions, has been isolated either by direct reduction of the iodide precursor, [{SiNMes}AlI], or in a stepwise manner via the intermediate dialumane, [{SiNMes}Al]2. Although the intermediate dialumane has not been observed by reduction of a Dipp‐substituted analogue (Dipp=2,6‐i‐Pr2C6H3), partial oxidation of the potassium alumanyl species, [{SiNDipp}AlK]2, where {SiNDipp}={CH2SiMe2N(Dipp)}2, provided the extremely encumbered dialumane [{SiNDipp}Al]2. [{SiNDipp}AlK]2 reacts with toluene by reductive activation of a methyl C(sp 3)‐H bond to provide the benzyl hydridoaluminate, [{SiNDipp}AlH(CH2Ph)]K, and as a nucleophile with BPh3 and RN=C=NR (R=i‐Pr, Cy) to yield the respective Al‐B‐ and Al‐C‐bonded potassium aluminaborate and alumina‐amidinate products. The dimeric structure of [{SiNDipp}AlK]2 can be disrupted by partial or complete sequestration of potassium. Equimolar reactions with 18‐crown‐6 result in the corresponding monomeric potassium alumanyl, [{SiNDipp}Al−K(18‐cr‐6)], which provides a rare example of a direct Al−K contact. In contrast, complete encapsulation of the potassium cation of [{SiNDipp}AlK]2, either by an excess of 18‐cr‐6 or 2,2,2‐cryptand, allows the respective isolation of bright orange charge‐separated species comprising the ‘free’ [{SiNDipp}Al]− alumanyl anion. Density functional theory (DFT) calculations performed on this moiety indicate HOMO‐LUMO energy gaps in the of order 200–250 kJ mol−1., Seven‐membered cyclic potassium diamidoalumanyls react with toluene by reductive activation of a methyl C(sp 3)−H bond and as a nucleophile with BPh3 and RN=C=NR (R=i‐Pr, Cy) to yield the respective Al‐B‐ and Al‐C‐bonded potassium aluminaborate and alumina‐amidinate products. The dimeric structure of [{SiNDipp}AlK]2 can be disrupted by partial or complete sequestration of potassium with 18‐cr‐6 or 2,2,2‐cryptand to provide either Al−K bonded or charge‐separated species comprising the ‘free’ alumanyl anion.
- Published
- 2021
30. Adatom Defect Induced Spin Polarization of Asymmetric Structures
- Author
-
Jia Wang, Xuhui Liu, Chunxu Wang, Wanyi Zhang, and Zhengkun Qin
- Subjects
carbon systems ,Full Paper ,General Chemistry ,Full Papers ,electronic states ,spin polarization ,chemical adsorption ,density functional theory - Abstract
The spin polarization of carbon nanomaterials is crucial to design spintronic devices. In this paper, the first‐principles is used to study the electronic properties of two defect asymmetric structures, Cap‐(9, 0)‐Def [6, 6] and Cap‐(9, 0)‐Def [5, 6]. We found that the ground state of Cap‐(9, 0)‐Def [6, 6] is sextet and the ground state of Cap‐(9, 0)‐Def [5, 6] is quartet, and the former has a lower energy. In addition, compared with Cap‐(9, 0) CNTs, the C adatom on C30 causes spin polarization phenomenon and Cap‐(9, 0)‐Def [6, 6] has more spin electrons than Cap‐(9, 0)‐Def [5, 6] structure. Moreover, different adsorb defects reveal different electron accumulation. This finding shows that spin polarization of the asymmetric structure can be adjusted by introducing adatom defects., Two defect asymmetric structures Cap‐(9, 0)‐Def [6, 6] CNT and Cap‐(9, 0)‐Def [5, 6] CNT have been constructed, and the former has a lower energy. In addition, the C adatoms on C30 causes spin polarization phenomenon, and Cap‐(9, 0)‐Def [6, 6] CNT has more spin electrons than Cap‐(9, 0)‐Def [5, 6] CNT.
- Published
- 2022
31. Water dissociation and COOH formation on Fe modified Cu(100) surface: A density functional theory study.
- Author
-
Hussain A and Javaid S
- Subjects
- Adsorption, Models, Molecular, Thermodynamics, Carbon Monoxide chemistry, Hydrogen chemistry, Water chemistry, Copper chemistry, Iron chemistry, Density Functional Theory, Carbon Dioxide chemistry, Surface Properties
- Abstract
Water splitting has emerged as a promising route for sustainable hydrogen production. In this research paper, adsorption and dissociation of H
2 O accompanied with dissociated constituents reactions with CO2 and CO have been investigated on Fe modified Cu(100) surface employing density functional theory (DFT) at GGA-PW91 level. The adsorption and other reactions carried out on Fe2-Cu(100) surfaces gave very promising results. The adsorption of H2 O on Fe top of this surface occurs yielding Eads -1.73 eV, which highlights a favorable adsorption on the Fe-modified Cu(100) surface. The activation energy for the water splitting reaction is found to be 0.65 eV, suggesting a feasible pathway for hydrogen evolution. The process also accompanies reaction energy of -0.54 eV. Furthermore, the interaction between carbon dioxide (CO2 ) and the H-atom on the surface lead to the formation of COOH through surmounting an activation barrier of 1.09 eV. The final position of COOH gets further stabilization having exothermicity of -0.43 eV. Another route for COOH formation from CO + OH operates on the Cu(100) part of the surface with a small activation barrier of 0.14 eV through exothermic process of -0.29 eV, however, diffusion of CO and OH from Fe to Cu is energetically expensive. This study signifies the consumption of CO and CO2 in addition to water splitting giving birth to useful products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
32. Chalcogen bonds
- Author
-
Trevor A. Hamlin, Lucas de Azevedo Santos, Teodorico C. Ramalho, F. Matthias Bickelhaupt, Theoretical Chemistry, AIMMS, and Chemistry and Pharmaceutical Sciences
- Subjects
Ab initio ,Thermodynamics ,coupled‐cluster ,010402 general chemistry ,benchmark study ,01 natural sciences ,Chalcogen ,noncovalent interactions ,0103 physical sciences ,Non-covalent interactions ,SDG 7 - Affordable and Clean Energy ,Theoretical Chemistry ,Basis set ,chalcogen bonds ,Physics ,chemistry.chemical_classification ,Full Paper ,010304 chemical physics ,Basis (linear algebra) ,Series (mathematics) ,coupled-cluster ,General Chemistry ,Full Papers ,0104 chemical sciences ,Computational Mathematics ,Coupled cluster ,chemistry ,density functional calculations ,Density functional theory - Abstract
We have performed a hierarchical ab initio benchmark and DFT performance study of D2Ch•••A− chalcogen bonds (Ch = S, Se; D, A = F, Cl). The ab initio benchmark study is based on a series of ZORA‐relativistic quantum chemical methods [HF, MP2, CCSD, CCSD(T)], and all‐electron relativistically contracted variants of Karlsruhe basis sets (ZORA‐def2‐SVP, ZORA‐def2‐TZVPP, ZORA‐def2‐QZVPP) with and without diffuse functions. The highest‐level ZORA‐CCSD(T)/ma‐ZORA‐def2‐QZVPP counterpoise‐corrected complexation energies (ΔE CPC) are converged within 1.1–3.4 kcal mol−1 and 1.5–3.1 kcal mol−1 with respect to the method and basis set, respectively. Next, we used the ZORA‐CCSD(T)/ma‐ZORA‐def2‐QZVPP (ΔE CPC) as reference data for analyzing the performance of 13 different ZORA‐relativistic DFT approaches in combination with the Slater‐type QZ4P basis set. We find that the three‐best performing functionals are M06‐2X, B3LYP, and M06, with mean absolute errors (MAE) of 4.1, 4.2, and 4.3 kcal mol−1, respectively. The MAE for BLYP‐D3(BJ) and PBE amount to 8.5 and 9.3 kcal mol−1, respectively., Fast and accurate! We have, for the first time, computed chalcogen bonds complexation energies in a procedure involving both a hierarchical series of ab initio methods and a hierarchical series of Gaussian‐type basis sets. Our best reference data, ZORA‐CCSD(T)/BS3+, identify the M06, M06‐2X, and B3LYP functionals as accurate DFT approaches for investigating chalcogen bonds in more complex systems.
- Published
- 2021
33. Comparing B3LYP and B97 Dispersion‐corrected Functionals for Studying Adsorption and Vibrational Spectra in Nitrogen Reduction
- Author
-
Grossman, Esther F., Daramola, Damilola A., and Botte, Gerardine G.
- Subjects
Materials science ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Catalysis ,Ammonia production ,Adsorption ,Transition metal ,Iridium ,Bond energy ,QD1-999 ,Full Paper ,010405 organic chemistry ,dispersion methods ,General Chemistry ,Full Papers ,iridium ,0104 chemical sciences ,Bond length ,ammonia synthesis ,Chemistry ,chemistry ,ammonia adsorption ,density functional calculations ,Physical chemistry ,Density functional theory - Abstract
Electrochemical ammonia synthesis is being actively studied as a low temperature, low pressure alternative to the Haber‐Bosch process. This work studied pure iridium as the catalyst for ammonia synthesis, following promising experimental results of Pt‐Ir alloys. The characteristics studied include bond energies, bond lengths, spin densities, and free and adsorbed vibrational frequencies for the molecules N2, N, NH, NH2, and NH3. Overall, these descriptive characteristics explore the use of dispersion‐corrected density functional theory methods that can model N2 adsorption – the key reactant for electrochemical ammonia synthesis via transition metal catalysis. Specifically, three methods were tested: hybrid B3LYP, a dispersion‐corrected form B3LYP‐D3, and semi‐empirical B97‐D3. The latter semi‐empirical method was explored to increase the accuracy obtained in vibrational analysis as well as reduce computational time. Two lattice surfaces, (111) and (100), were compared. The adsorption energies are stronger on (100) and follow the trend EB3LYP>EB3LYP‐D3>EB97‐D3 on both surfaces., Iridium for Ammonia Synthesis: Increasing the yield of ammonia in the electrochemical synthesis process gets researchers one step closer to replacing the energy‐intensive Haber‐Bosch process. Benchtop experiments with iridium have been shown to produce good ammonia yields via the electrochemical process. The present study investigates which Density Functional Theory methods best characterize the molecules involved in catalysis over iridium and provides theoretical benchmarks that can be used to understand the underlying mechanism.
- Published
- 2021
34. Oxygen Evolution and Reduction Reaction Activity Investigations on Fe, Co or Ni embedded Tetragonal Graphene by A Thermodynamical Full‐Landscape Searching Scheme
- Author
-
Yanqin Gai
- Subjects
Materials science ,doping ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,law.invention ,Catalysis ,Metal ,Tetragonal crystal system ,single-atom catalyst ,Transition metal ,law ,QD1-999 ,density functional theory ,Full Paper ,010405 organic chemistry ,Graphene ,Oxygen evolution ,General Chemistry ,Full Papers ,0104 chemical sciences ,Chemistry ,electrochemistry ,visual_art ,ORR/OER ,visual_art.visual_art_medium ,Physical chemistry ,Density functional theory - Abstract
Single transition metal (TM) atoms such as Fe, Co and Ni occupying a carbon divacancy in tetragonal graphene (TG) and bonded with four nitrogen atoms (TM@N4TG) as electrocatalysts are investigated by means of first‐principles calculations. To consider the effect of solvent species on the local configuration of the active single metal, a thermodynamical full‐landscape searching (TFLS) scheme is employed. The calculated thermodynamic overpotentials (ηtd) from our TFLS indicate that Co@N4TG displays high catalytic activity toward both oxygen evolution reaction (OER) and reduction reaction (ORR), with ηtd OER and ηtd ORR as 0.397 and 0.357 V, respectively. Its OER potential cannot be captured if only one four electron reaction loop (FERL) is considered. The actual active pathways do not always turn out to be the reactions starting from the bare site. Our findings demonstrate that TG is a promising support and TM confined TD can be used to design effective and cheap multifunctional electrocatalysts., Doped Tetragonal Graphene (TG) as electrocatalyst? The pre‐adsorption of solvent functional groups (OH, O and OOH) can tune the adsorption strength of species. A thermodynamic full‐landscape searching scheme is proposed where all the possible reactions were considered. Co@N4TG is confirmed to be a favorable bifunctional single‐atom electrocatalyst for both OER and ORR.
- Published
- 2021
35. Amphiphilic Silver Nanoparticles for Inkjet-Printable Conductive Inks.
- Author
-
Ivanišević, Irena, Kovačić, Marin, Zubak, Marko, Ressler, Antonia, Krivačić, Sara, Katančić, Zvonimir, Gudan Pavlović, Iva, and Kassal, Petar
- Subjects
CONDUCTIVE ink ,SILVER nanoparticles ,PARTICLE size distribution ,NANOPARTICLES ,ACRYLIC acid ,PRINTED electronics - Abstract
The large-scale manufacturing of flexible electronics is nowadays based on inkjet printing technology using specially formulated conductive inks, but achieving adequate wetting of different surfaces remains a challenge. In this work, the development of a silver nanoparticle-based functional ink for printing on flexible paper and plastic substrates is demonstrated. Amphiphilic silver nanoparticles with narrow particle size distribution and good dispersibility were prepared via a two-step wet chemical synthesis procedure. First, silver nanoparticles capped with poly(acrylic acid) were prepared, followed by an amidation reaction with 3-morpholynopropylamine (MPA) to increase their lipophilicity. Density functional theory (DFT) calculations were performed to study the interactions between the particles and the dispersion medium in detail. The amphiphilic nanoparticles were dispersed in solvents of different polarity and their physicochemical and rheological properties were determined. A stable ink containing 10 wt% amphiphilic silver nanoparticles was formulated and inkjet-printed on different surfaces, followed by intense pulsed light (IPL) sintering. Low sheet resistances of 3.85 Ω sq
–1 , 0.57 Ω sq–1 and 19.7 Ω sq–1 were obtained for the paper, coated poly(ethylene terephthalate) (PET) and uncoated polyimide (PI) flexible substrates, respectively. Application of the nanoparticle ink for printed electronics was demonstrated via a simple flexible LED circuit. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
36. A Joint Experimental and Theoretical Study on the Structural and Spectroscopic Properties of the Piv-Pro-d-Ser-NHMe Peptide.
- Author
-
Menant S, Tognetti V, Oulyadi H, Guilhaudis L, and Ségalas-Milazzo I
- Subjects
- Peptides chemistry, Protein Structure, Secondary, Nuclear Magnetic Resonance, Biomolecular, Molecular Dynamics Simulation, Circular Dichroism, Density Functional Theory
- Abstract
In this paper, we investigate the secondary structure of the Piv-Pro-d-Ser-NHMe peptide by means of nuclear magnetic resonance (NMR) and electronic circular dichroism (ECD) experiments, in conjunction with theoretical simulations based on molecular dynamics and time-dependent density functional theory calculations including polarizable embedding to account for solvent effects. The various experimental and theoretical protocols are assessed and validated, and are shown to provide a consistent description of the turn structure adopted by this peptide in solution. In addition, a simple fitting procedure is proposed to make the simulated and experimental ECD almost perfectly match. This full methodology is finally tested on another small peptide, enlightening its efficiency and robustness.
- Published
- 2024
- Full Text
- View/download PDF
37. Mechanistic and predictive studies on the oxidation of furans by cytochrome P450: A DFT study.
- Author
-
Han Y, Cheng S, Guo F, Xiong J, and Ji L
- Subjects
- Hydroxylation, Kinetics, Thermodynamics, Furans chemistry, Oxidation-Reduction, Cytochrome P-450 Enzyme System metabolism, Cytochrome P-450 Enzyme System chemistry, Density Functional Theory
- Abstract
Furan-containing compounds distribute widely in food, herbal medicines, industrial synthetic products, and environmental media. These compounds can undergo oxidative metabolism catalyzed by cytochrome P450 enzymes (CYP450) within organisms, which may produce reactive products, possibly reacting with biomolecules to induce toxic effects. In this work, we performed DFT calculations to investigate the CYP450-mediated metabolic mechanism of furan-ring oxidation using 2-methylfuran as a model substrate, meanwhile, we studied the regioselective competition of another hydroxylation reaction involving methyl group of 2-methylfuran. As a result, we found the toxicological-relevant cis-enedione product can be produced from O-addition directly via a concerted manner without formation of an epoxide intermediate as traditionally believed. Moreover, our calculations demonstrate the kinetic and thermodynamic feasibility of both furan-ring oxidation and methyl hydroxylation pathways, although the former pathway is a bit more favorable. We then constructed a linear model to predict the rate-limiting activation energies (ΔE*) of O-addition with 11 diverse furan substates based on their adiabatic ionization potentials (AIPs) and condensation Fukui functions (CFFs). The results show a good predictive ability (R
2 =0.94, Q2 CV =0.87). Therefore, AIP and CFF with clear physichem meanings relevant to the mechanism, emerge as pivotal molecular descriptors to enable the fast prediction of furan-ring oxidation reactivities for quick insight into the toxicological risk of furans, using just ground-state calculations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
38. Tackling antibiotic contaminations in wastewater with novel Modified-MOF nanostructures: A study of molecular simulations and DFT calculations.
- Author
-
Salahshoori I, Namayandeh Jorabchi M, Mazaheri A, Mirnezami SMS, Afshar M, Golriz M, and Nobre MAL
- Subjects
- Adsorption, Nanostructures chemistry, Metal-Organic Frameworks chemistry, Molecular Dynamics Simulation, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents analysis, Wastewater chemistry, Water Pollutants, Chemical chemistry, Water Pollutants, Chemical analysis, Density Functional Theory
- Abstract
The contamination of wastewater with antibiotics has emerged as a critical global challenge, with profound implications for environmental integrity and human well-being. Adsorption techniques have been meticulously investigated and developed to mitigate and alleviate their effects. In this study, we have investigated the adsorption behaviour of Erythromycin (ERY), Gentamicin (GEN), Levofloxacin (LEVO), and Metronidazole (MET) antibiotics as pharmaceutical contaminants (PHCs) on amide-functionalized (RC (=O)NH
2 )/MIL-53 (Al) (AMD/ML53A), using molecular simulations and density functional theory (DFT) calculations. Based on our DFT calculations, it becomes apparent that the adsorption tendencies of antibiotics are predominantly governed by the presence of AMD functional groups on the adsorbent surface. Specifically, hydrogen bonding (HB) and van der Waals (vdW) interactions between antibiotics and AMD groups serve as the primary mechanisms facilitating adsorption. Furthermore, we have observed that the adsorption behaviors of these antibiotics are influenced by their respective functional groups, molecular shapes, and sizes. Our molecular simulations delved into how the AMD/ML53A surfaces interact with antibiotics as PHCs. Moreover, various chemical quantum descriptors based on Frontier Molecular Orbitals (FMO) were explored to elucidate the extent of AMD/ML53A adsorption and to assess potential alterations in their electronic properties throughout the adsorption process. Monte Carlo simulation showed that ERY molecules adsorb stronger to the adsorbent in acidic and basic conditions than other contaminants, with high energies: -404.47 kcal/mol in acidic and -6375.26 kcal/mol in basic environments. Molecular dynamics (MD) simulations revealed parallel orientation for the ERY molecule's adsorption on AMD/ML53A with 80% rejection rate. In conclusion, our study highlighted the importance of modeling in developing practical solutions for removing antibiotics as PHCs from wastewater. The insights gained from our calculations can facilitate the design of more effective adsorption materials, ultimately leading to a more hygienic and sustainable ecosystem., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
39. DFT and AIMD insights into heterogeneous dissociation of 2-chlorothiophenol on CuO(111) surface: Impact of H 2 O and OH.
- Author
-
Wang X, Hadizadeh MH, Wang W, Hu Y, Zhou Y, Xu F, Sun Y, and Wang W
- Subjects
- Adsorption, Catalysis, Water chemistry, Molecular Dynamics Simulation, Hydroxides chemistry, Surface Properties, Sulfhydryl Compounds chemistry, Copper chemistry, Density Functional Theory
- Abstract
Copper oxides are vital catalysts in facilitating the formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) through heterogeneous reactions in high-temperature industrial processes. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. The initial step in this process is the metal-catalyzed production of chlorothiophenoxy radicals (CTPRs) from CTPs via dissociation reactions. This work combines density functional theory (DFT) calculations with ab initio molecular dynamics (AIMD) simulations to explore the formation mechanism of the adsorbed 2-CTPR from 2-CTP, with the assistance of CuO(111). Our study demonstrates that flat adsorption configurations of 2-CTP on the CuO(111) surface are more stable than vertical configurations. The CuO(111) surface acts as a strong catalyst, facilitating the dissociation of 2-CTP into the adsorbed 2-CTPR. Surface oxygen vacancies enhance the adsorption of 2-CTP on the CuO(111) surface, while moderately suppressing the dissociation of 2-CTP. More importantly, water molecules and surface hydroxyl groups actively promote the dissociation of 2-CTP. Specifically, water directly participates in the reaction through "water bridge", enabling a barrier-free process. This research provides molecular-level insights into the heterogeneous generation of dioxins with the catalysis of metal oxides in fly ash from static and dynamic aspects, providing novel approaches for reducing dioxin emissions and establishing dioxin control strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
40. Effect of calcium and phosphorus on ammonium and nitrate nitrogen adsorption onto iron (hydr)oxides surfaces: CD-MUSIC model and DFT computation.
- Author
-
Jia M, Ma J, Zhou Q, Liu L, Jie X, Liu H, Qin S, Li C, Sui F, Fu H, Xie H, Wang L, and Zhao P
- Subjects
- Adsorption, Ferric Compounds chemistry, Models, Chemical, Hydrogen-Ion Concentration, Calcium chemistry, Nitrogen chemistry, Phosphorus chemistry, Nitrates chemistry, Ammonium Compounds chemistry, Density Functional Theory
- Abstract
Calcium (Ca
2+ ) and phosphorous (PO4 3- ) significantly influence the form and effectiveness of nitrogen (N), however, the precise mechanisms governing the adsorption of ammonium nitrogen (NH4 -N) are still lacking. This study employed batch adsorption experiments, charge distribution and multi-site complexation (CD-MUSIC) models and density functional theory (DFT) calculations to elucidate the mechanism by which Ca+ -N) and nitrate nitrogen (NO3 - -N) are still lacking. This study employed batch adsorption experiments, charge distribution and multi-site complexation (CD-MUSIC) models and density functional theory (DFT) calculations to elucidate the mechanism by which Ca2+ and PO4 3- affect the adsorption of NH4 + -N and NO3 - -N on the goethite (GT) surface. The results showed that the adsorption of NH4 + -N on the GT exhibited an initial increase followed by a decrease as pH increased, peaking at a pH of 8.5. Conversely, the adsorption of NO3 - -N decreased with rising pH. According to the CD-MUSIC model, Ca2+ minimally affected the NH4 + -N adsorption on the GT but enhanced NO3 - -N adsorption via electrostatic interaction, promoting the adsorption of ≡FeOH-NO3 - and ≡Fe3 O-NO3 - species. Similarly, PO4 3- inhibited the adsorption of ≡FeOH-NO3 - and ≡Fe3 O-NO3 - species. However, PO4 3- boosted NH4 + -N adsorption by facilitating the formation of ≡Fe3 O-NH4 + via electrostatic interaction and site competition. DFT calculations indicates that although bidentate phosphate (BP) was beneficial to stabilize NH4 + -N than monodentate phosphate (SP), SP-NH4 + was the main adsorption configuration at pH 5.5-9.5 owing the prevalence of SP on the GT surface under site competition of NH4 + -N. The results of CD-MUSIC model and DFT calculation were verified mutually, and provide novel insights into the mechanisms underlying N fixation and migration in soil., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
41. Adsorption of per- and poly-fluoroalkyl substances (PFAS) on Ni: A DFT investigation.
- Author
-
Mohamed MS, Chaplin BP, and Abokifa AA
- Subjects
- Adsorption, Water Pollutants, Chemical chemistry, Alkanesulfonic Acids chemistry, Thermodynamics, Catalysis, Fluorocarbons chemistry, Nickel chemistry, Density Functional Theory, Caprylates chemistry
- Abstract
Electrocatalytic destruction of per- and polyfluoroalkyl substances (PFAS) is an emerging approach for treatment of PFAS-contaminated water. In this study, a systematic ab initio investigation of PFAS adsorption on Ni, a widely used electrocatalyst, was conducted by means of dispersion-corrected Density Functional Theory (DFT) calculations. The objective of this investigation was to elucidate the adsorption characteristics and charge transfer mechanisms of different PFAS molecules on Ni surfaces. PFAS adsorption on three of the most thermodynamically favorable Ni surface facets, namely (001), (110), and (111), was investigated. Additionally, the role of PFAS chain length and functional group was studied by comparing the adsorption characteristics of different PFAS compounds, namely perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and perfluorobutanoic acid (PFBA). For each PFAS molecule-Ni surface facet pair, different adsorption configurations were considered. Further calculations were carried out to reveal the effect of solvation, pre-adsorbed atomic hydrogen (H), and surface defects on the adsorption energy. Overall, the results revealed that the adsorption of PFAS on Ni surfaces is energetically favorable, and that the adsorption is primarily driven by the functional groups. The presence of preadsorbed H and the inclusion of solvation produced less exothermic adsorption energies, while surface vacancy defects showed mixed effects on PFAS adsorption. Taken together, the results of this study suggest that Ni is a promising electrocatalyst for PFAS adsorption and destruction, and that proper control for the exposed facets and surface defects could enhance the adsorption stability., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ahmed Abokifa reports financial support was provided by National Alliance for Water Innovation. Brian Chaplin reports financial support was provided by National Alliance for Water Innovation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
42. Exploring long-range fluorine-carbon J-coupling for conformational analysis of deoxyfluorinated disaccharides: A combined computational and NMR study.
- Author
-
Chaloupecká E, Kurfiřt M, Červenková Šťastná L, Karban J, and Dračínský M
- Subjects
- Carbon chemistry, Carbohydrate Conformation, Molecular Conformation, Fluorine chemistry, Disaccharides chemistry, Density Functional Theory, Magnetic Resonance Spectroscopy
- Abstract
In this study, we investigated the potential of long-range fluorine-carbon J-coupling for determining the structures of deoxyfluorinated disaccharides. Three disaccharides, previously synthesized as potential galectin inhibitors, exhibited through-space fluorine-carbon J-couplings. In our independent conformational analysis of these disaccharide derivatives, we employed a combination of density functional theory (DFT) calculations and nuclear magnetic resonance (NMR) experiments. By comparing the calculated nuclear shieldings with the experimental carbon chemical shifts, we were able to identify the most probable conformers for each compound. A model comprising fluoromethane and methane molecules was used to study the relationship between molecular arrangements and intermolecular through-space J-coupling. Our study demonstrates the important effect of internuclear distance and molecular orientation on the magnitude of fluorine-carbon coupling. The experimental values for the fluorine-carbon through-space couplings (TSCs) of the disaccharides corresponded with values calculated for the most probable conformers identified by the conformational analysis. These results unlock the broader application of fluorine-carbon TSCs as powerful tools for conformational analysis of flexible molecules, offering valuable insights for future structural investigations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
43. Insights into the hydrolysis/alcoholysis/ammonolysis mechanisms of ethylene naphthalate dimer using density functional theory (DFT) method.
- Author
-
Luo X and Li Q
- Subjects
- Hydrolysis, Naphthalenes chemistry, Kinetics, Ethylenes chemistry, Plastics chemistry, Thermodynamics, Models, Chemical, Density Functional Theory
- Abstract
Hydrolysis, alcoholysis and ammonolysis are viable routes for the efficient degradation and recycling of polyethylene naphthalate (PEN) plastic waste. Various possible hydrolysis/alcoholysis/ammonolysis reaction pathways for the degradation mechanism of the ethylene naphthalate dimer were investigated using the density functional theory (DFT) B3P86/6-31++G(d,p). To determine the thermodynamic and kinetic parameters, geometric structure optimization and frequency calculation were performed on a range of intermediates, transition states, and products associated with the reaction. The calculation results show that the highest energy barrier of the main element reaction step in hydrolysis is about 169.0 kJ/mol, the lowest is about 151.0 kJ/mol for ammonolysis, and the second is about 155.0 kJ/mol for alcoholysis. The main hydrolysis products of the ethylene naphthalate dimer are 2,6-naphthalenedicarboxylic acid and ethylene glycol; the main products of alcoholysis are dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol, and the main products of ammonolysis are naphthalene-2,6-dicarboxamide and ethylene glycol. Furthermore, in the process of ethylene naphthalate dimer hydrolysis/alcoholysis/ammonolysis, the decomposition reaction in the NH
3 atmosphere is better than that in methanol, and the reaction in CH3 OH is better than that in the H2 O molecular environment, and the increase in reaction temperature can increase its spontaneity. Our study presents the molecular mechanism of PEN hydrolysis/alcoholysis/ammonolysis and provides a reference for studying the degradation of other plastic wastes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
44. Density functional theory-based screening of Ti 4 C 3 O 2 -loaded single atoms for efficient selective catalytic oxidation of formaldehyde.
- Author
-
Zheng Z, Zhang C, Li J, Fang D, Tan P, Fang Q, and Chen G
- Subjects
- Catalysis, Air Pollution, Indoor, Air Pollutants chemistry, Molecular Dynamics Simulation, Formaldehyde chemistry, Oxidation-Reduction, Density Functional Theory, Titanium chemistry
- Abstract
Indoor formaldehyde (HCHO) pollution poses a major risk to human health. Low-temperature catalytic oxidation is an effective method for HCHO removal. The high activity and selectivity of single atomic catalysts provide a possibility for the development of efficient non-precious metal catalysts. In this study, the most stable single-atom catalyst Ti-Ti
4 C3 O2 was screened by density functional theory among many single atomic catalysts with two-dimensional (2D) monolayer Ti4 C3 O2 as the support. The computational results show that Ti-Ti4 C3 O2 is highly selective to HCHO and O2 in complex environments. The HCHO oxidation reaction pathways are proposed based on the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. According to the reaction energy and energy span models, the E-R mechanism has a lower maximum energy barrier and higher catalytic efficiency than the L-H mechanism. In addition, the stability of the Ti-Ti4 C3 O2 structure and active center was verified by diffusion energy barrier and ab initio molecular dynamics simulations. The above results indicate that Ti-Ti4 C3 O2 is a promising non-precious metal catalyst. The present study provides detailed theoretical insights into the catalytic oxidation of HCHO by Ti-Ti4 C3 O2 , as well as an idea for the development of efficient non-precious metal catalysts based on 2D materials., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Cheng Zhang reports financial support was provided by National Natural Science Foundation of China. Cheng Zhang reports a relationship with Huazhong University of Science and Technology that includes: non-financial support. nothing If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
45. Effect of interlayer spacing on the electronic and optical properties of SnS2/graphene/SnS2 sandwich heterostructure: a density functional theory study.
- Author
-
Idisi, David O., Benecha, Evans M., Mwakikunga, Bonex, and Asante, Joseph K. O.
- Abstract
The formation of metal dichalcogenide heterostructures enables tailoring their properties for future optoelectronics and energy storage. The current paper focuses on the study of the effect of interlayer spacing on the electronic and optical properties of SnS
2 /graphene/SnS2 sandwich heterostructure, using density functional theory electronic structure calculations. We find low cohesive energies/ per atom ( 0.0506 → 0.0514 eV) for all the various interlayer spacing configurations (1–5 Å) considered in this study, implying the feasibility of experimental realization. The Mulliken charge transfer analysis suggests negative to positive net charge ( - 0.12 → 0.18 ) transfer for 1–3 Å threshold interlayer spacing, which implies acceptor and donor charge transfer configurations. The density of states of SnS2 /graphene/SnS2 retains unoccupied states for all the interlayer spacing configurations, which can be attributed to localized exciton states and strong electronic coupling between the electrons within the heterostructure layers. We further find a strong optical response and localized electronic transport, which can pave the way for optoelectronic applications of this material heterostructure. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
46. Investigating the potential of triclinic ABSe3 (A = Li, Na, K, Rb, Cs; B = Si, Ge, Sn) perovskites as a new class of lead-free photovoltaic materials.
- Author
-
Mahmoud, Eman Khalafalla, El-dek, S. I., Farghali, Ahmed A., and Taha, Mohamed
- Abstract
In recent years, chalcogenide perovskites have emerged as promising candidates with favorable structural, electrical, and optical properties for photovoltaic applications. This paper explores the structural, electronic, and optical characteristics of ABSe
3 perovskites (where A = Li, Na, K, Rb, Cs; B = Si, Ge, Sn) in their triclinic crystallographic phases using density functional theory. The stability of these materials is ensured by calculating formation energies, tolerance factors (Tf ), and phonon dispersion. The Eform values of all ABSe3 are negative, suggesting favorable thermodynamic stability. The Tf values range between 0.82 and 1.1, which is consistent with stable perovskites. The phonon dispersion analysis of the chalcogenide perovskites revealed no imaginary frequencies in any of the vibrational modes, confirming their stability. The electronic band structures and corresponding density of states are computed to unveil the semiconducting nature of the studied compounds. These perovskites are promising for high-performance solar cells due to their indirect bandgaps (Eg , 1.10–2.33 eV) and a small difference between these indirect and direct gaps (0.149–0.493 eV). The Eg values increase as the ionic radii of A-site elements increase (Li < Na < K < Rb < Cs). At the B-site, Si-based chalcogenides have the largest Eg values, followed by Sn-based and then Ge-based materials. Furthermore, optical properties such as the real part and imaginary part of the dielectric function, refractive index extinction coefficient, optical conductivity, absorption coefficient, reflectivity, and energy loss are predicted within the energy range of 0–50 eV. Several ABSe3 materials, particularly LiGeSe3 and NaGeSe3 , demonstrated optical properties comparable to both traditional and emerging materials, suggesting their potential for effective use in solar cells. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
47. Molecular Simulation Analysis of Polyurethane Molecular Structure under External Electric Field.
- Author
-
Pang, Zhiyi, Huang, Shangshi, Li, Yi, Zhang, Yiyi, and Qin, Rui
- Subjects
COMPUTATIONAL chemistry ,MOLECULAR structure ,COMPUTATIONAL electromagnetics ,ELECTRIC fields ,DENSITY functional theory ,CHEMICAL bonds - Abstract
Polyurethane (PU) materials are extensively utilized in power equipment. This paper introduces a comprehensive evaluation method that combines electromagnetics and computational chemistry based on the Density Functional Theory (DFT) to elucidate the impact of external electric fields on the molecular structure of PU during electrical contact. The study focuses on the microstructural and molecular energy changes in the hard (HS) and soft (SS) segments of PU under the influence of an electric field of uniform intensity. Findings indicate that the total energy of HS molecules decreases markedly as the electric field intensity increases, accompanied by a significant rise in both the dipole moment and polarizability. Conversely, the total energy and polarizability of the SS molecules decrease, while the dipole moment experiences a slight increase. Under the influence of a strong electric field, HS molecules tend to stretch towards the extremities of the main chain, leading to structural instability and the cleavage of hydroxyl O-H bonds. Meanwhile, the carbon chain of the SS molecules twists towards the center under the electric field, with no chemical bond rupture observed. At an electric field intensity of 8.227 V/nm, the HOMO-LUMO gap of the HS molecule narrows sharply, signifying a rapid decline in the molecular structure stability, corroborated by infrared spectroscopy analysis. These findings offer theoretical insights and guidance for the modification of PU materials in power equipment applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Bis(amino acidato)copper(II) compounds in blood plasma: a review of computed structural properties and amino acid affinities for Cu2+ informing further pharmacological research.
- Author
-
Sabolović, Jasmina
- Subjects
COPPER ,AMINO compounds ,COORDINATION compounds ,CHEMICAL models ,DENSITY functional theory - Abstract
Copyright of Archives of Industrial Hygiene & Toxicology / Arhiv za Higijenu Rada I Toksikologiju is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2024
- Full Text
- View/download PDF
49. Doping properties in Co3-xNixO4, comparison between p-DFT and experimental values.
- Author
-
Aguirre, C A, DÍaz, P, Laroze, D., Joya, M R, Barba-Ortega, J, and Polo, A S Mosquera
- Subjects
PHASE transitions ,FERMI surfaces ,DENSITY of states ,FERMI energy ,DENSITY functional theory ,SPINEL group - Abstract
In the present work, we numerically and experimentally study the Co 3 - x Ni x O 4 (spinel-like oxides) system. Using the perturbative density functional theory (p-DFT) method, we start the study from the homogeneous sample ( x = 0 ), obtaining the main electronic properties (band structure (BS), density of states (DOS), and Fermi surface (FS)). Subsequently, we doped (x) with Ni atoms in different proportions (0–7% respectively, taking 56 atoms as 100% and the percentage of doping, on this percentage). As we increase the doping (x ≠ 0) , we have found that the forbidden gap decreases and the Fermi energy (FE) decreases, causing the material to exhibit a transition phase for a particular doping value. In addition, we find that more bands are generated when the system is doped, which would be responsible for the phase transition. The data from the theoretical analysis carried out in this paper was compared with the experimental data of various widely accepted works. Some of the results, when compared with the information available from the experimental ones, show good agreement. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Strain and Substrate-Induced Electronic Properties of Novel Mixed Anion-Based 2D ScHX 2 (X = I/Br) Semiconductors.
- Author
-
Rawat, Ashima and Pandey, Ravindra
- Subjects
BAND gaps ,DENSITY functional theory ,SUBSTRATES (Materials science) ,MIXING height (Atmospheric chemistry) ,ELECTRONIC equipment - Abstract
Exploration of compounds featuring multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offers an avenue for developing materials with the prospect of novel functionality. In this paper, we present the results for a mixed anion layered material, ScHX
2 (X: Br, I) based on density functional theory. The result predicted the ScHX2 (X: Br, I) monolayers to be stable and semiconducting. Notably, the electronic and mechanical properties of the ScHX2 monolayers are comparable to well-established 2D materials like graphene and MoS2 , rendering them highly suitable for electronic devices. Additionally, these monolayers exhibit an ability to adjust their band gaps and band edges in response to strain and substrate engineering, thereby influencing their photocatalytic applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.