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Non-enzymatic electrochemical blood glucose sensors often suffer from issues such as requiring an alkaline environment, limited monitoring range, and poor anti-interference properties. Carbon substrates have been demonstrated to improve the performance of non-enzymatic sensors, but complex and energy-consuming manufacturing processes restrict their use. Herein, a simple and green approach for the preparation of 3D porous Au/Au-Pt networks (PAAPNs) is proposed using tissue paper for recycling as the nanomaterial substrate to deposit Au-Pt bimetallic nanoparticles. The unique structure of the PAAPNs sensor allows for low-potential operation (-1.0 V) with a wide monitoring range (-0.25 to 36 mM) in a neutral environment. Moreover, the sensor exhibited excellent selectivity (<10% response of interference) even without the use of an anti-interference outer membrane. Further investigation using density functional theory (DFT) simulation revealed the synergistic effect between Au and Pt in promoting glucose oxidation. Overall, this work provides a simple and low-carbon footprint method for creating carbon substrates from tissue paper for recycling, offering new opportunities for fabricating novel value-added nanomaterials for medical sensing applications. [ABSTRACT FROM AUTHOR]

A new fluorescent probe (T2) containing pyrene-hydrazone furan moieties was developed and synthesized through a two-step process and then coated onto filter paper to form a paper-based sensor for TNT detection. The T2 sensor uses photoinduced electron transfer (PET) induced fluorescence quenching to detect TNT. The sensor properties were studied using fluorescence spectra, 1H-NMR titration and density functional theory (DFT) calculations. The reaction time of the T2 paper-based sensor for TNT detection was only five minutes. A smartphone was used as an alternative instrument to detect fluorescence signals and a typical image J-processing application was employed to evaluate the grayscale values of the smartphone-captured photographs. The sensor showed a linear concentration range for TNT detection of between 30–500 μM and a detection limit of 30 μM. The T2 paper-based sensor was found to have high selectivity and sensitivity, and it can successfully detect and image TNT in actual samples. This research demonstrates that a T2 paper-based sensor is a promising alternative for TNT detection owing to its short reaction time, high selectivity, sensitivity, and easy applicability. [ABSTRACT FROM AUTHOR]

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]

[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]

In the current research work "4-{[1-(2,5-dihydroxyphenyl)ethylidene]amino}-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one" chemosensor (C1) synthesized by condensation reaction using "4-amino-1,2-dihydro-1,5-dimethyl-2-phenylpyrazol-3-one" and "2,5-dihydroxy actophenone" was used as the effective sensor of metal ion. The C1 shows absorption peak at 326 nm due to the C = C bond (π-π* transition), while the absorption peak at 364 nm is caused by the C = O bond (n-π* transition). In the presence of copper, C1 only demonstrated a redshift in absorption peak from 364 to 425 nm. Even in the presence of other competing metal ions, the hypsochromic shift of the absorption band and the quenching of the fluorescence emission intensity were different for detecting Cu2+, in CH3OH-H2O (v/v = 6:4). The capacity of the C1 to bind with Cu2+ was further proved using DFT simulations. The complex C1 + Cu2+ has a HOMO–LUMO energy gap of 2.8002 eV, which is lesser than C1 (2.9991 eV) showing improvement in the stability of the C1 + Cu2+ complex. Using the Benesi-Hildebrand and Scatchard plots, calculated Kb values were to be 47,340 and 48369 M−1 respectively, showing the creation of stable complexation between Cu2+ and C1 with 1:1 stoichiometry. The limit of detection (LOD) for Cu2+ ion was 649 nM. Strip sheets were also built and tested to detect varying amounts of Cu2+ in aqueous solution, and their color change suggested that they might be used for on-site Cu2+ detection in polluted water. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate a microwave-assisted chemical reduction technique to exfoliate a few layers of graphene from the natural waste material, ‘coconut shell’. The microwave irradiation coconut shell is subjected to structural, morphological and functional groups characterization methods including SEM, Raman, FTIR and XPS spectroscopic analyses. The formation of biomass reduced graphene (BRG) has been confirmed through Raman and FTIR spectroscopic analyzes with the presence of D, G and 2D and other functional spectral bands, respectively. The surface topography of the BRG exhibits two-dimensional mat structures with wrinkle topography, imaged by electron microscopic techniques. The metallic behaviour of the BRG is evaluated by band structure calculation using density functional theory. The synthesized nanostructure has been evaluated for exhaled diabetic breath sensing application by fabricating sensor device on the paper-based substrate by roll-to-roll coating technique. The BRG sensor exhibited enhanced sensing response at a very lower concentration of diabetic biomarker with long term stability and rapid response/recovery time of 1.11 s/41.25 s, respectively. Based on our findings, the microwave-assisted BRG is a potential candidate for fabricating highly scalable, inherently safe, economically viable and excellent sensing performance to detect exhaled diabetic breath at room temperature. [ABSTRACT FROM AUTHOR]

It is significant to develop low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we constructed P-doped NiCo2S4 nanowire arrays on carbon fiber paper (NiCo2S4−xPx/CFP) as a HER electrocatalyst in both acidic and alkaline media. Benefitting from P doping into NiCo2S4, the as-prepared NiCo2S4−xPx/CFP exhibits low HER overpotentials of 80 and 132 mV in acidic and alkaline media at a cathodic current density of 10 mA cm−2, respectively, which are far superior to counterparts of NiCo2S4 nanowire arrays on the carbon fiber paper (NiCo2S4/CFP). Meanwhile, the NiCo2S4−xPx/CFP presents excellent HER stability of 20 hours in acidic and alkaline media. From the results of density functional theory calculations, P doping can not only optimize the hydrogen adsorption energetics on each kind of atomic site of catalysts, but also strengthen the H2O molecule binding ability on the catalyst surface for the alkaline HER and favor kinetics of hydrogen adsorption and H2 formation on the catalyst surface for the acidic HER, eventually improving overall HER performances. The investigation of the HER mechanism modulated by P doping in our work offers novel inspiration to develop highly efficient ternary metal sulfides for the HER. [ABSTRACT FROM AUTHOR]

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]

Peroxidase‐mimicking nanozymes have been extensively studied, however, their application is limited by the requirement for an acidic pH. Herein, the development of Co‐doped mesoporous cerium oxide (Co‐m‐ceria) is reported, which operates optimally at a near‐neutral pH and exhibits a peroxidase‐like catalytic efficiency that is 600‐times higher than that of pristine m‐ceria. Density functional theory (DFT) calculations for the application of pristine and various metal‐doped m‐ceria in peroxidase‐like reactions under different pH environments are conducted to select Co as the appropriate dopant. The high peroxidase‐like activity of Co‐m‐ceria under neutral conditions and its mesoporous nature enable its application in a one‐pot cascade reaction system, wherein biomarkers of oxidative enzymes can be detected without altering the pH. Five different oxidative enzymes are immobilized in the pores of Co‐m‐ceria at high loadings, followed by incorporation of the enzyme‐containing Co‐m‐ceria in paper microfluidic devices for the convenient and simultaneous detection of multiple biomarkers. The Co‐m‐ceria‐incorporated paper microfluidic device enables the selective and sensitive determination of multiple biomarkers using a smartphone‐acquired image. This study demonstrates the potential of the rational design of nanozymes and their application in paper microfluidic devices, laying the groundwork for future applications of nanozymes in point‐of‐care testing environments. [ABSTRACT FROM AUTHOR]

Despite much efforts to stabilize sodium metal anodes for promoting their commercial applications, achieving a safe cycling process without intrinsic dendrite growth remains difficult owing to the unstable reaction interface and irregular sodium metal propagation. Herein, fluorine‐superdoped carbon nanotubes with a fluorine content of 14.38 at% are achieved using a new oxidation‐assisted plasma strategy, and then alternately assembled with cellulose nanofibrils to form periodical conductive/dielectric composite paper with outstanding mechanical properties. The superdoping of fluorine facilitates the construction of a NaF‐dominated solid electrolyte interphase layer, while the periodical conductive/dielectric network re‐homogenizes electric field distribution around irregular sodium protrusions, realizing a "bottom‐up" sodium orientation deposition and the "self‐correction" functionality during sodium plating/stripping process. Density functional theory calculations reveal that the specific oxygen species (CO/CO) and fluorine species (semi‐ionic CF/covalent CF2) on the surface of carbon matrix, could remarkably trap active fluorine fragments and generate NaF with sodium metal, respectively, which promotes the superdoping of fluorine and forms dendrite‐free sodium anodes. This delicate structure renders the sodium anodes a low nucleation overpotential of ≈7 mV, high Coulombic efficiency of 99.5% over 300 cycles at 3 mA cm−2, stable operation for up to 2100 h under ≈16 mV, and excellent full battery performance. [ABSTRACT FROM AUTHOR]

Platinum (Pt)‐based electrocatalysts are the benchmark catalysts for hydrogen evolution reaction (HER); however, they are limited by the scarcity and high price. Introducing an adequate substrate to disperse and anchor Pt‐based species is a feasible pathway to improve the utilization efficiency. Herein, a quick and continuous spray drying route is proposed to fabricate 3D crumpled Ti3C2Tx MXene loaded with sub‐nanometer platinum clusters (Pt/MXene). The 3D crumpled structure inhibits the restacking of layered MXene nanosheets and guarantees the fully exposure of Pt clusters. The as‐prepared catalyst exhibits excellent HER performances comparable to commercial Pt/C, including a low overpotential of 34 mV to reach a current density of 10 mA cm−2, a superior mass activity (1847 mA mgPt−1), a small Tafel slope (29.7 mV dec−1), and a high turnover frequency (10.66 H2 s−1). The improved activity of Pt/MXene can be attributed to the charge transfer from Pt clusters to MXene, which weakens the hydrogen adsorption, as evidenced by the density functional theory calculations. The present contribution proposes a novel strategy to anchor low‐mass‐loading sub‐nanometer precious metal clusters on crumpled MXene with fully exposed active sites for catalysis. [ABSTRACT FROM AUTHOR]

The superadiabatic dynamical density functional theory (superadiabatic-DDFT) is a promising new method for the study of colloidal systems out-of-equilibrium. Within this approach, the viscous forces arising from interparticle interactions are accounted for in a natural way by explicitly treating the dynamics of the two-body correlations. For bulk systems subject to spatially homogeneous shear, we use the superadiabatic-DDFT framework to calculate the steady-state pair distribution function and the corresponding viscosity for low values of the shear-rate. We then consider a variant of the central approximation underlying this superadiabatic theory and obtain an inhomogeneous generalization of a rheological bulk theory due to Russel and Gast. This paper thus establishes for the first time a connection between DDFT approaches, formulated to treat inhomogeneous systems, and existing work addressing nonequilibrium microstructure and rheology in bulk colloidal suspensions. [ABSTRACT FROM AUTHOR]

In this paper, benchmark results are presented on the calculation of vertical electronic excitation energies using a long-range second-order polarization propagator approximation (SOPPA) description with a short-range density functional theory description based on the Perdew–Burke–Ernzerhof (PBE) functional. The excitation energies are investigated for 132 singlet states and 71 triplet states across 28 medium-sized organic molecules. The results show that overall SOPPA-srPBE always performs better than PBE and that SOPPA-srPBE performs better than SOPPA for singlet states, but slightly worse than SOPPA for triplet states when CC3 results are the reference values. [ABSTRACT FROM AUTHOR]

Since the 1940s, it has been known that diffusion in crystalline solids occurs due to lattice defects. The diffusion of defects can have a great impact on the processing and heat treatment of materials as the microstructural changes caused by diffusion can influence the material qualities and properties. It is, therefore, vital to be able to control the diffusion. This implies that we need a deep understanding of the interactions between impurities, matrix atoms, and intrinsic defects. The role of density functional theory (DFT) calculations in solid-state diffusion studies has become considerable. The main parameters to obtain in defect diffusion studies with DFT are formation energies, binding energies, and migration barriers. In particular, the utilization of the nudged elastic band and the dimer methods has improved the accuracy of these parameters. In systematic diffusion studies, the combination of experimentally obtained results and theoretical predictions can reveal information about the atomic diffusion processes. The combination of the theoretical predictions and the experimental results gives a unique opportunity to compare parameters found from the different methods and gain knowledge about atomic migration. In this Perspective paper, we present case studies on defect diffusion in wide bandgap semiconductors. The case studies cover examples from the three diffusion models: free diffusion, trap-limited diffusion, and reaction diffusion. We focus on the role of DFT in these studies combined with results obtained with the experimental techniques secondary ion mass spectrometry and deep-level transient spectroscopy combined with diffusion simulations. [ABSTRACT FROM AUTHOR]

The waste cooking oil is upcycled into N-doped carbon nanosheets, enabling fast Na+/K+ storage by means of surface charge modulation. [Display omitted] • Waste cooking oil was selected as precursor to prepare hard carbon anode materials. • NWCOC650 takes on a porous nanosheet structure with turbo layers. • NWCOC650 has a coexistence storage mechanism of adsorption/intercalation-filling. • Head group (–NH 2) can produce a synergistic effect with N-5/6/Q and graphene. • NWCOC650 exhibits excellent performances for sodium/potassium-ion batteries. Hard carbons are significant in sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, the structural defects of hard carbons lead to poor rate performance and cycling stability, which need further improvement. The waste cooking oil was used as the precursor to synthesize 3D carbon nanosheets (NWCOC) with amino nitrogen functional groups, multi-layered pores, and expanded interlayer spacing. The excellent electrochemical properties of NWCOC were investigated and it was demonstrated that NWCOC can significantly improve the adsorption of Na+/K+ on hard carbons, substantially enhancing the embedding/de-embedding of Na+/K+, reducing the diffusion distance of ions and electrons, and improving their adaptability to volume changes. In situ XRD and Raman characterization reveal that the Na storage mechanism of NWCOC is mainly based on adsorption/intercalation-filling. Combined with density functional theory, it is shown that the porous structures doped with nitrogen have a greater propensity for ion adsorption, resulting in increased ion capture and storage. As expected, NWCOC650 exhibits high capacities of 489.4 and 388.3 mAh/g in SIBs and PIBs. NWCOC650 displays superior performance in the Na 3 V 2 (PO 4) 3 /NWCOC650 full cell, achieving a capacity of 107.84 mAh/g. This work presents a new perspective on the synthesis and mechanisms of high-performance anodes for SIBs and PIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of two-armed indole appended Schiff base conjoined 1,2,3-Triazole based click derived bis-organosilane and bis-organosilatrane is synthesized. • The designed Schiff bases are developed as colorimetric, fluorescent and paper-based selective sensors for Al(III). • The binding capabilities are in sighted by using absorption and emission titrations that determine the 4 and 5 high sensitivity and ultratrace low detection limits of 1.41 × 10−9 M and 0.17 × 10−9 M. • The insights into the optical signal changes are discussed. Metal ions have significant roles in diagnosis, industry, human health, and the environment. To design and develop new lucid molecular receptors for the selective detection of metal ions is important for environmental and medical applications. In the present work, two-armed indole appended Schiff bases conjoined with 1,2,3-Triazole bis-organosilane and bis-organosilatrane skelton sensors for naked eye colorimetric and fluorescent detection sensors for Al(III) are developed. The introduction of Al(III) in sensor 4 and 5 show red shift in UV–visible spectra, changes in fluorescence spectra and immediate color change from colorless to dark yellow. Furthermore, the pH and time response studies were explored for both sensors 4 & 5. The sensors 4 and 5 exhibited significantly low detection limit (LOD) in nano-molar range 1.41 × 10−9 M and 0.17 × 10−9 M respectively from emission titration. The LOD form absorption titration was found to be 0.6 × 10−7 M for sensor 4 and 0.22 × 10−7 M for sensor 5. In addition, the sensing model is developed as paper based sensor for its practical applicability. The theoretical calculations were performed on Gaussian 03 program by relaxing the structures using Density functional theory. [ABSTRACT FROM AUTHOR]

For many centuries, paper was considered the main support for recording cultural achievements all over the world. Archives represent the historical memory of our past, and the book conservation represents one main concern since many books and documents kept in libraries and archives are at risk because of their fragility. The use of portable, not destructive technique like NIR μ-Raman spectroscopy represents a valid instrument for monitoring the documentary heritage. In the present study, we investigated the degradation process, associated to the polymers breaking, in order to propose a successful kinetic model for determining the ageing time of cellulose. We compared the calculated results with respect to both experimental samples and literature data, covering a period of seven centuries, from XV to XXI centuries. Proposed model starts directly from Raman spectra, in particular by monitoring the band at 1100 cm − 1 ascribed to C-O-C inter-monomers bond, whose relative intensity is related to the cellulose chain length. We obtained a very good agreement with the experimental data with 8% of accuracy. Finally, with the help of Density Functional Theory (DFT) simulations, we confirmed our model by studying the structure and the grade of cellulose crystallinity in the paper. In particular, the reverse trend of the band at 900 cm − 1 , related to the crystallinity grade of the cellulose, and the band at 1100 cm − 1 , as a function of the dimer unit cell structure, supported the kinetic model, suggesting a shear stress like effect as the origin of the cellulose chain length decrease. [ABSTRACT FROM AUTHOR]

A probe based on merocyanine dye was synthesized as a salt of p‐toluenesulfonate. Owing to the high solubility of merocyanine dye in water and H‐bonding ability, it was investigated for anion‐induced aggregation properties in the buffered medium [CH3CN: water (1 : 1/v: v)]. The probe recognized the existence of cyanide ion by forming an H‐bond and displacing the p‐toluenesulfonate group. The probe displayed a bluish‐purple color in response to cyanide ion addition, which was initially light pink. The complex formation and aggregation properties of the probe were investigated using techniques like naked eye detection, digital colorimetry, UV‐Visible, 1H‐NMR, and dynamic light scattering (DLS). Paper and solution‐based techniques aided by a smartphone were also used successfully in the determination process. An excellent limit of detection value (LOD) was witnessed in all the techniques exploited for sensing cyanide ions. Methods based on density functional theory (DFT) were also used to investigate the complex formation and observed a good correlation in experimental and theoretical results. [ABSTRACT FROM AUTHOR]

Designing photochromic systems that exhibit tunable print/erase responses is seldom studied but critical to the implementation of rewritable paper. Previous systems printed information with photocatalysts limited to specific wavelengths and light sources and rarely considered how polymers used in film formation affect erasing of information. Herein, different visible/UV light responses are achieved by engineering the formation of oxygen vacancy defects in titanium dioxide/reduced graphene oxide composite photocatalysts. Defects are manipulated during synthesis by controlling the water concentration in a mixed solvent system, which leads to tunable photochromic response of redox dyes. Furthermore, because the accessibility of ambient oxygen directly impacts the kinetics of recoloration, tailoring the oxygen barrier properties of polyvinyl alcohol via modulating inherent polymer structure as well as the external environment, the recoloration can be further tuned to meet various application purposes. The resulting insight will assist fellow researchers in tailoring defects in photocatalyst systems for superior functional design. [ABSTRACT FROM AUTHOR]

Presently, the use of several pesticides has been continuously rising owing to the increase in the production of food materials to meet the requirements of the growing population of the world. The safety of food materials with regards to pesticides is an important health concern for people. With this aim, we have developed a smartphone-assisted paper-based sensor impregnated with citrate capped Cu@Ag core–shell nanoparticles (NPs) for selective determination of phenthoate pesticides in water and food samples. The mechanism for selective detection is based on the high affinity of phenthoate to interact with silver NPs present on the surface of CuNPs, which results in aggregation and a change in the color of the paper device. Furthermore, the proposed mechanism and interaction of phenthoate with Cu@Ag NPs was theoretically investigated by density functional theory (DFT) using Gaussian 16.0 software. The linear range for the determination of phenthoate was found in the range of 50–1500 μg L−1, with a limit of detection of 15 μg L−1, and a 92.6 to 97.4% recovery, and the interference studies demonstrated the selectivity for the determination of the target analyte from complex sample matrices. Finally, paper impregnated with Cu@Ag was exploited for the monitoring of the phenthoate pesticide in different water and food samples. The advantages of this paper-based sensor, coupled with a smartphone readout system, are that is it is user-friendly, easy-to-use, cost-effective, and can be applied at the sample source compared to sophisticated analytical instruments. [ABSTRACT FROM AUTHOR]

To address the challenge of performance portability and facilitate the implementation of electronic structure solvers, we developed the basic matrix library (BML) and Parallel, Rapid O(N), and Graph-based Recursive Electronic Structure Solver (PROGRESS) library. The BML implements linear algebra operations necessary for electronic structure kernels using a unified user interface for various matrix formats (dense and sparse) and architectures (CPUs and GPUs). Focusing on density functional theory and tight-binding models, PROGRESS implements several solvers for computing the single-particle density matrix and relies on BML. In this paper, we describe the general strategies used for these implementations on various computer architectures, using OpenMP target functionalities on GPUs, in conjunction with third-party libraries to handle performance critical numerical kernels. We demonstrate the portability of this approach and its performance in benchmark problems. [ABSTRACT FROM AUTHOR]

Hydration and, in particular, the coordination number of a metal ion is of paramount importance as it defines many of its (bio)physicochemical properties. It is not only essential for understanding its behavior in aqueous solutions but also determines the metal ion reference state and its binding energy to (bio)molecules. In this paper, for divalent metal cations Ca 2 + , Cd 2 + , Cu 2 + , Fe 2 + , Hg 2 + , Mg 2 + , Ni 2 + , Pb 2 + , and Zn 2 + , we compare two approaches for predicting hydration numbers: (1) a mixed explicit/continuum DFT-D3//COSMO-RS solvation model and (2) density functional theory based ab initio molecular dynamics. The former approach is employed to calculate the Gibbs free energy change for the sequential hydration reactions, starting from [M( H 2 O)2]2+ aqua complexes to [M( H 2 O) 9]2+, allowing explicit water molecules to bind in the first or second coordination sphere and determining the most stable [M( H 2 O) n]2+ structure. In the latter approach, the hydration number is obtained by integrating the ion–water radial distribution function. With a couple of exceptions, the metal ion hydration numbers predicted by the two approaches are in mutual agreement, as well as in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Paper is an important material for many applications. During the centuries, it has been the most widely used writing support and therefore paper degradation is a major issue for cultural heritage. The main component of paper is cellulose, one of the most abundant biomaterials on Earth. Cellulose oxidation is mainly responsible for the yellowing of the ancient samples, through the formation of chromophores. In order to investigate this issue and the chromophores' role, we exploit the optical properties combining non-destructive experiments and theoretical calculations based on ab-initio techniques. In this paper, we illustrate the method and show its application to three ancient paper samples. The procedure we describe is a precious tool for cultural heritage preservation: indeed, the approach we present is based on non-invasive and non-destructive measurements that allows a microscopic understanding of cellulose-based artifacts degradation. [ABSTRACT FROM AUTHOR]

TurboGenius is an open-source Python package designed to fully control ab initio quantum Monte Carlo (QMC) jobs using a Python script, which allows one to perform high-throughput calculations combined with TurboRVB [Nakano et al. J. Phys. Chem. 152, 204121 (2020)]. This paper provides an overview of the TurboGenius package and showcases several results obtained in a high-throughput mode. For the purpose of performing high-throughput calculations with TurboGenius, we implemented another open-source Python package, TurboWorkflows, that enables one to construct simple workflows using TurboGenius. We demonstrate its effectiveness by performing (1) validations of density functional theory (DFT) and QMC drivers as implemented in the TurboRVB package and (2) benchmarks of Diffusion Monte Carlo (DMC) calculations for several datasets. For (1), we checked inter-package consistencies between TurboRVB and other established quantum chemistry packages. By doing so, we confirmed that DFT energies obtained by PySCF are consistent with those obtained by TurboRVB within the local density approximation (LDA) and that Hartree–Fock (HF) energies obtained by PySCF and Quantum Package are consistent with variational Monte Carlo energies obtained by TurboRVB with the HF wavefunctions. These validation tests constitute a further reliability check of the TurboRVB package. For (2), we benchmarked the atomization energies of the Gaussian-2 set, the binding energies of the S22, A24, and SCAI sets, and the equilibrium lattice parameters of 12 cubic crystals using DMC calculations. We found that, for all compounds analyzed here, the DMC calculations with the LDA nodal surface give satisfactory results, i.e., consistent either with high-level computational or with experimental reference values. [ABSTRACT FROM AUTHOR]

In a binary mixture, stripes refer to a one-dimensional periodicity of the composition, namely, a regular alternation of layers filled with particles of mostly one species. We have recently introduced [Munaò et al., Phys. Chem. Chem. Phys. 25, 16227 (2023)] a model that possibly provides the simplest binary mixture endowed with stripe order. The model consists of two species of identical hard spheres with equal concentration, which mutually interact through a square-well potential. In that paper, we have numerically shown that stripes are present in both liquid and solid phases when the attraction range is rather long. Here, we study the phase behavior of the model in terms of a density functional theory capable to account for the existence of stripes in the dense mixture. Our theory is accurate in reproducing the phases of the model, at least insofar as the composition inhomogeneities occur on length scales quite larger than the particle size. Then, using Monte Carlo simulations, we prove the existence of solid stripes even when the square well is much thinner than the particle diameter, making our model more similar to a real colloidal mixture. Finally, when the width of the attractive well is equal to the particle diameter, we observe a different and more complex form of compositional order in the solid, where each species of particle forms a regular porous matrix holding in its holes the other species, witnessing a surprising variety of emergent behaviors for a very basic model of interaction. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the spin transport properties of binuclear manganese phthalocyanine (M n 2 P c 2) spintronic devices sandwiched between two nickel electrodes using the non-equilibrium Green's function method in combination with density functional theory. Based on the calculation results, the M n 2 P c 2 device exhibited excellent spin-filtering capabilities, demonstrating an exceptionally high spin filter efficiency (SFE). Irrespective of the parallel or antiparallel orientation of magnetization in the electrodes, we observed that when both manganese atoms were in a spin-up state, the SFE of spin-resolved currents under finite bias and the thermoelectric currents induced by temperature gradients at fixed temperatures were both close to 100%. The large spin Seebeck polarization of the M n 2 P c 2 device was also obtained at low reference temperatures. This study explores the potential for developing multifunctional spintronic single-molecule devices using Ni − M n 2 P c 2. [ABSTRACT FROM AUTHOR]

In this paper we establish a connection between density functional theory (DFT) for lattice models and common real-space DFT. We consider the lattice DFT description of a two-level model subject to generic interactions in Mermin's DFT formulation in the grand canonical ensemble at finite temperature. The case of only density–density and Hund's rule interaction studied in earlier work is shown to be equivalent to an exact-exchange description of DFT in the real-space picture. In addition, we also include the so-called pair-hopping interaction which can be treated analytically and, crucially, leads to non-integer occupations of the Kohn–Sham (KS) levels even in the limit of zero temperature. Treating the hydrogen molecule in a minimal basis is shown to be equivalent to our two-level lattice DFT model. By means of the fractional occupations of the KS orbitals (which, in this case, are identical to the many-body ones) we reproduce the results of full configuration interaction, even in the dissociation limit and without breaking the spin symmetry. Beyond the minimal basis, we embed our HOMO-LUMO model into a standard DFT calculation and, again, obtain results in overall good agreement with exact ones without the need of breaking the spin symmetry. [ABSTRACT FROM AUTHOR]

This paper provides a critical overview of experimental and computational studies conducted on additive manufacturing (AM) or 3D printing using bimetallic alloys. The review acknowledges the complexity introduced by mechanical interactions and significant interface anisotropies in multi-material AM, making the mechanisms of phase change and microstructure evolution more intricate. Various computational models, such as density functional theory (DFT), phase field, and finite element models, employed in the study of 3D printed bimetallic materials are discussed. The paper highlights the importance of future research in developing quantitative predictions that can simulate and forecast microstructure formation during the AM process. By incorporating computational modeling, this review underlines the potential for overcoming challenges associated with the intricate interactions between different materials in multi-material AM (MMAM). [ABSTRACT FROM AUTHOR]

Compared with traditional water electrolysis, electrolysis of seawater has larger resources and a brighter future. However, seawater contains more elements that have greater corrosive effects on electrodes; especially chloride ions (seawater contains more chloride ions) have the greatest impact. The existence of the corrosion problem creates greater difficulties in electrolyzing seawater, further limiting the efficiency of the electrocatalyst for electrolysis of seawater. In this paper, we report a Mn-doped Ni 2 P/Cu 3 P as an environmentally friendly monofunctional electrode for seawater electrolysis, which was made by a simple hydrothermal phosphatization operation method. The experimental results show that Mn-doped Ni 2 P/Cu 3 P presents overpotential of only 161 mV for oxygen evolution reaction (OER) at iR compensation of 90 and a current density of 10 mA cm−2. It has a small Tafel slope (25.15 mV dec−1) and a large capacitance (9.58 mF cm−2 on 1 × 1 nickel foam), which exceeds most reported oxygen evolution activities of non-precious metal-based electrocatalysts for electrolysis of alkaline seawater. The performance of Ni 2 P/Cu 3 P was probably significantly enhanced due to Mn doping by some characterization means. Through Density functional theory (DFT) analysis, it is known that the doping of Mn gives a large enhancement in the adsorption energy of water when Ni 2 P/Cu 3 P is electrolyzed with seawater. This paper provides train of thought for the exploration of excellent electrocatalysts for electrolysis of alkaline seawater. The experimental results show that Mn-dopedNi 2 P/Cu 3 P present overpotential of only 161 mV at i-R compensation of 90 for oxygen evolution reaction in alkaline seawater. [Display omitted] • Mn-doped Ni 2 P/Cu 3 P electrodes was synthesized for the first time through hydrothermal processes. • The overpotential of Mn-doped Ni 2 P/Cu 3 P electrode is only 161 mV at 10 mA cm−2 for OER. • The doping of Mn gives a large enhancement in the adsorption energy of water. [ABSTRACT FROM AUTHOR]

Context: In this paper, the optimum coverage of 4.44% and the optimum adsorption sites were determined for the Be3N2 adsorption system of O atoms at different coverages based on density functional theory. The electronic and optical properties of the model were investigated by applying bending deformation to the model at these coverage and adsorption sites. Adsorption of O atoms disrupts the geometrical symmetry of Be3N2, resulting in orbital rehybridization and lowering its band gap. Bending deformation causes the band gap of the adsorbed O atom structure of Be3N2 to first increase and then decrease, resulting in the modulation of its band gap. With increasing bending deformation, the adsorbed system is redshifts, and the degree of redshift increases with increasing bending deformation. Methods: All calculations in this paper were performed using the first-principles-based CASTEP module of Materials Studio (MS). The generalized gradient approximation (GGA) plane-wave pseudopotential method and the Perdew-Burke-Ernzerhof (PBE) Perdew et al. Phys Rev Lett 77:3865, 1996 generalized functional were used in the geometry optimization and calculation process to calculate the exchange–correlation potential between electrons. The effect of coverage on the electronic and optical properties of the Be3N2-adsorbed O atom system was investigated by adsorbing different numbers of O atoms on a monolayer of Be3N2. The Be3N2 protocell contains two N atoms and three Be atoms with a space community of P6/MMM (No.191). The original cell was expanded 3 times along the direction of the base vectors a and b in the Be3N2 plane to create a 3 × 3 × 1 monolayer Be3N2 supercell system. A vacuum layer of 15 Å is set in the direction of the crystal plane of the vertical monolayer Be3N2 supercell to eliminate interactions between adjacent layers. In the overall energy convergence test of the Be3N2 supercell, the plane wave truncation energy was set to 500 eV, and the energy difference between the calculations given in the literature Reyes-Serrato et al. J Phys Chem Solids 59:743-6, 1998 using 550 eV was less than 0.01 eV, verifying the reliability of the data at a truncation energy of 500 eV. The Monkhorst–Pack special k-point sampling method Monkhorst et al. Phys Rev B 13:5188, 1976 was used in the structural calculations, and the grid was set to 3 × 3 × 1. The geometric optimization parameters are set as follows: the self-consistent field iteration convergence criterion is 2.0 × 10−6 eV, and the iterative accuracy convergence value is not less than 1.0 × 10−5 eV/atom for the total force of each atom and less than 0.03 eV/Å for all atomic forces. In addition the high-symmetry k-point path is taken as Γ(0,0,0) → M(0,0.5,0) → K(− 1/3,2/3,0) → Γ(0,0,0) Chen et al, AIP Adv 8:105105, 2018. [ABSTRACT FROM AUTHOR]

Electrolysis of water for production of hydrogen has become one of the most fascinating methods to relieve the energy crisis and environmental pollution. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam through a two-step hydrothermal process, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. Under an alkaline condition of 1 M KOH, Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2, and using Co–NiS/Mo 2 S 3 as both cathode and anode, only the potential of 1.574 V is required to drive a current density of 50 mA cm−2, with a relatively good durability over 15 h. Density functional theory (DFT) analysis show that the ΔG H* of Co–NiS is closer to 0 and its density of states near the Fermi energy level is higher, suggesting that Co–NiS improves the electrical conductivity of Co–NiS/Mo 2 S 3 and plays a significant catalytic action. This work proposes novel insights for the future exploration of novel sulfur-based composite electrocatalysts with excellent HER performance. In this paper, a series of M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials was in situ grown on Ni foam by a two-step hydrothermal method, and the synthesized Co–NiS/Mo 2 S 3 material present excellent hydrogen evolution reaction (HER) properties. [Display omitted] • M-NiS/Mo 2 S 3 (M = Co, Fe, Ce and Bi) materials were successfully synthesized by hydrothermal processes. • Co–NiS/Mo 2 S 3 electrode shows excellent catalysis in the cathode reaction of water and water electrolysis. • Co–NiS/Mo 2 S 3 requires only overpotential of 142 mV to achieve a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]

In this study, we reported the photoluminescence (PL) behaviour of a new intramolecular charge transfer (ICT) compound, ((E)-2-(((2-hydroxynaphthalen-1-yl)methylene)amino)benzoic acid, (HABA), which shows ICT solvent effect in aprotic solvents as confirmed by absorption and emission spectra. While in protic solvents including water and ethanol, the charge transfer (CT) band significantly reduces. Remarkable fluorescence enhancement in the blue region was also observed for HABA in polar protic solvents. We described such phenomena as “specific solvent effect”. It can be ascribed to the hydrogen bonding formation between HABA and protic solvents, which not only causes significant reduction in the rate of internal conversion but also elevates the energy gap. Density functional theory (DFT) calculations as well as the dynamics analysis were performed to further verify the existence of hydrogen bonding complexes. Stronger emission turn-on effect was observed on HABA solid film when it is treated with water and base solution. The stimuli-responsive fluorescence of HABA enables a new green printing technique that uses water/base as the ink, affording fluorescent handwritings highly distinct from the background. Thermoanalysis of the dye suggests the nice thermostability, which is highly desired for real-world printing in a wide temperature range. [ABSTRACT FROM AUTHOR]

Boron Nitride Nanotubes are valued due to their physical and chemical properties. They can be found their possible applications in the field of design and developing of optoelectronic devices of new generation. In this paper the transport and electronic properties of both clear Boron Nitride and Boron Nitride Nanotube with embedded carbon atoms have been calculated in the framework of Density Functional Theory (DFT). Results show that nanodevice with embedded carbon atoms has wider transmission spectrum than clear one. It has been computed transmission eigenvalues for both nanodevices. Nanodevice with impurity has higher transmission eigenvalues than clear one. [ABSTRACT FROM AUTHOR]

[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]

Molybdenum disulfide (MoS 2 ) is considered as a promising candidate to Pt-based catalysts. Literatures report the active centers of MoS 2 locate at its edges, while the perfect in-plane domains are not active. In this study, a simple Co Mo S precursor decomposition approach is used to synthesize Co-doped MoS 2 in-situ grown graphite paper (GP) substrate. Electrochemical analyses reveal the Co-doped MoS 2 possesses excellent electrocatalytic activity comparable to Pt. Density functional theory (DFT) calculations indicate the inert in-plane S atoms neighboring the doped Co atoms become active towards triiodide reduction, as revealed by the adsorption energies ( E ad ) of iodine atom decreasing from 0.36 eV to −0.52 eV, identical with value obtained from Pt (−0.52 eV). Due to increased active sites, highly conductive of GP, and excellent electrical connection between Co-doped MoS 2 and GP substrate, the dye-sensitized solar cell fabricated using Co-doped MoS 2 /GP as counter electrode (CE) shows higher photoelectric conversion efficiency (7.26%) than those based on MoS 2 /GP CE (6.57%) and platinized F-doped tin oxide (Pt/FTO) electrode (6.87%). [ABSTRACT FROM AUTHOR]

The Pauli kinetic energy functional and its functional derivative, termed Pauli potential, play a crucial role in the successful implementation of orbital-free density functional theory for electronic structure calculations. However, the exact forms of these two quantities are not known. Therefore, perforce, one employs the approximate forms for the Pauli functional or Pauli potential for performing orbital-free density functional calculations. In the present study, we developed a feed-forward neural network-based representation for the Pauli potential using a 1-dimensional (1-D) model system. We expanded density in terms of basis functions, and the coefficients of the expansion were used as input to a feed-forward neural network. Using the neural network-based representation of the Pauli potential, we calculated the ground-state densities of the 1-D model system by solving the Euler equation. We calculated the Pauli kinetic energy using the neural network-based Pauli potential employing the exact relation between the Pauli kinetic energy functional and the potential. The sum of the neural network-based Pauli kinetic energy and the von Weizsäcker kinetic energy resulted in an accurate estimation of the total kinetic energy. The approach presented in this paper can be employed for the calculation of Pauli potential and Pauli kinetic energy, obviating the need for a functional derivative. The present study is an important step in the advancement of application of machine learning-based techniques toward the orbital-free density functional theory-based methods. [ABSTRACT FROM AUTHOR]

Recent measurements of the third harmonic scattering responses of molecules have given a new impetus for computing molecular second hyperpolarizabilities (γ) and for deducing structure–property relationships. This paper has employed a variety of wavefunction and density functional theory methods to evaluate the second hyperpolarizability of the p-nitroaniline prototypical push-pull π-conjugated molecule, addressing also numerical aspects, such as the selection of an integration grid and the impact of the order of differentiation vs the achievable accuracy by using the Romberg quadrature. The reliability of the different methods has been assessed by comparison to reference Coupled-Cluster Singles and Doubles with perturbative treatment of the Triples results. On the one hand, among wavefunction methods, the MP2 scheme offers the best accuracy/cost ratio for computing the static γ. On the other hand, using density functional theory, γ remains a challenging property to compute because all conventional, global hybrid or range-separated hybrid, exchange–correlation functionals underestimate static γ values by at least 15%. Even tuning the range-separating parameter to minimize the delocalization errors does not enable to improve the γ values. Nevertheless, the original double-hybrid B2-PLYP functional, which benefits from 27% of PT2 correlation and 53% Hartree–Fock exchange, provides accurate estimates of static γ values. Unfortunately, the best performing exchange–correlation functionals for γ are not necessarily reliable for the first hyperpolarizability, β, and vice versa. In fact, the β of p-nitroaniline (pNA) could be predicted, with a good accuracy, with several hybrid exchange–correlation functionals (including by tuning the range-separating parameter), but these systematically underestimate γ. As for γ, the MP2 wavefunction method remains the best compromise to evaluate the first hyperpolarizability of pNA at low computational cost. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) are widely investigated since they have rather high theoretical capacity (1675 mAh g −1 ) and specific energy (∼2600 Wh kg −1 ). However, their poor capacity retention limits their practical use. Herein, sulfur-loaded activated carbon was used as the cathode of LSB. The functionalized carbon fiber paper (CFP) containing carboxyl and amide groups was used as an interlayer of LSB. With these designs of the LSB, it can provide excellent charge storage performance with high capacity retention. The LSB using ethylenediamine (EDA)-functionalized CFP interlayer exhibits an outstanding initial discharge capacity of 1800 mAh g −1 and 1472 mAh g −1 after the stable SEI formation with ca. 92% capacity retention and low degradation rate of 0.046% per cycle after 200 cycles at 1C. A strong adsorption capacity of polysulfide and amide functional group of EDA-functionalized CFP reduces the shuttle mechanism phenomenon. The density functional theory calculation shows that EDA-functionalized CFP can strongly bind high order polysulfides (Li 2 Sn, 4 ≤ n ≤ 8) when compared to other functional groups. Furthermore, the fully charged LSB cell with ca. 3.5 mg cm −2 sulfur loading content on the cathode can practically supply electricity to a nominal 3-V spinning motor for 25 min demonstrating the practical use of our as-fabricated LSB. [ABSTRACT FROM AUTHOR]

This paper reports the derivation and implementation of the electric dipole-magnetic dipole and electric dipole-electric quadrupole polarizability tensors at the density functional theory level with periodic boundary conditions (DFT-PBC). These tensors are combined to evaluate the Buckingham/Dunn tensor that describes the optical rotation (OR) in oriented chiral systems. We describe several aspects of the derivation of the equations and present test calculations that verify the correctness of the tensor formulation and their implementation. The results show that the full OR tensor is completely origin invariant as for molecules and that PBC calculations match molecular cluster calculations on 1D chains. A preliminary investigation on the choice of density functional, basis set, and gauge indicates a similar dependence as for molecules: the functional is the primary factor that determines the OR magnitude, followed by the basis set and to a much smaller extent the choice of gauge. However, diffuse functions may be problematic for PBC calculations even if they are necessary for the molecular case. A comparison with experimental data of OR for the tartaric acid crystal shows reasonable agreement given the level of theory employed. The development presented in this paper offers the opportunity to simulate the OR of chiral crystalline materials with general-purpose DFT-PBC methods, which, in turn, may help to understand the role of intermolecular interactions on this sensitive electronic property. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is considered as a green and efficient way of hydrogen production. How to promote the performance of electrode and develop stable non-precious metal catalysts has caused extensive research. One of the effective strategies is combining two or more catalytic materials to build heterogeneous structures. In this paper, a series of Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 heterostructured materials were synthesized to in-situ grow Ni 3 S 2 /Ni 3 Sn 2 S 2 on Ni foam with a 3D porous structure by modulating the substance ratio of elemental cobalt and elemental sulfur through a one-step hydrothermal process. The materials have superior oxygen evolution reaction (OER) properties and urea oxidation reaction (UOR) performance. Under an alkaline electrolyte of 1 M KOH, for OER, Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 only requires overpotential of 251 mV to obtain a current density of 10 mA cm−2. In an alkaline solution of 1 M KOH +0.5 M urea, for UOR, only the potential of 1.326 V was demanded for the catalyst to reach a current density of 50 mA cm−2, but its stability over 15 h was average. Density Functional Theory (DFT) analyses suggest that Co–Ni 3 S 2 has better metallic properties and promote the dynamics in catalysis. This study put forward a new thought for future research on nickel-tin binary metal sulfide hybrid electrocatalysts with excellent freshwater, seawater and urea oxidation properties. In this paper, a series of Co x -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials was in situ grown on Ni foam by a one-step hydrothermal method, and the synthesized Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 material present excellent water and urea oxidation properties. [Display omitted] • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 materials were successfully synthesized by hydrothermal processes. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 electrode shows excellent catalysis in the cathode reaction of water and urea. • Co 0.3 -Ni 3 S 2 /Ni 3 Sn 2 S 2 requires only potential of 1.326 V to achieve a current density of 50 mA cm−2 for UOR. [ABSTRACT FROM AUTHOR]

Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. [Display omitted] Using the WIEN2k code, first-principles simulations of ZrXH 3 (X = Zn, Cd) hydride perovskites are performed to determine their hydrogen storage properties. The purpose of this study is to investigate their structural, optoelectronic, hydrogen storage, mechanical and thermoelectric properties. The structural analysis demonstrates their stability through the heat of formation along with desorption temperature and shows that these compositions belong to the orthorhombic space group Cmcm (no.63). The band structure and density of states are estimated for electronic characteristics, indicating the metallic nature of both compositions. Analysis of elastic properties such as elastic constants, Pugh's ratio, bulk modulus, Poisson's ratio, and anisotropy factor are explored to determine the mechanical stability of these compositions and demonstrate their suitability as a transport medium in hydrogen storage systems even at higher pressure. To study the optical behavior of the perovskites under consideration for hydrogen storage applications, the dielectric parameters, dielectric constants, refractive index, optical conductivity, absorptivity, and energy loss function are studied. The present paper represents the initial theoretical effort toward future exploration of these materials for hydrogen storage applications. • Stability of ZrXH 3 (X = Zn, Cd) hydride perovskites is confirmed by Enthalpy of formation. • ZrXH 3 (X = Zn, Cd) hydride perovskites have high value of decomposition temperature. • The gravimetric hydrogen storage capacities comes out to be 1.89 % and 1.46 % respectively. • Metallic behavior is reveled by electronic structure of these hydrides. [ABSTRACT FROM AUTHOR]

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]

In this paper, based on the first-principle calculations of hybrid density functional theory, the MoSTe/g-GeC of the Z-scheme heterostructure is constructed. The stability, electronic properties, optical absorption properties, and photocatalytic mechanism of the heterostructure is investigated. The band structure of MoSTe/g-GeC heterostructure is staggered, and the bandgap is 0.47 eV. The built-in electric field from g-GeC to MoSTe, with a size of 1.03 eV. The optical absorption coefficient of MoSTe/g-GeC heterostructures is significantly higher than that of MoSTe and g-GeC layer. When pH ranges from 0 to 7, the reduction reaction occurs in g-GeC layer, and the oxidation reaction occurs in the MoSTe layer. In the MoSTe/g-GeC heterostructure under different stresses, the band structure is arranged in a staggered manner. Importantly, under tensile strain, the bandgap of MoSTe/g-GeC heterostructure can be changed from the indirect into a direct bandgap. The bandgap of heterostructure decreases under the strain. In addition, the analysis of the photocatalytic mechanism shows that the redox reaction of the MoSTe/g-GeC heterostructure occurs on the layer with strong redox ability, and their light absorption ability is significantly enhanced compared to single-layers, which effectively improves the photocatalytic properties. It's a potential high-efficiency photocatalytic materials for direct Z-scheme heterostructure. In this paper, the stability, electronic properties, optical absorption properties, and photocatalytic mechanism of the MoSTe/g-GeC heterostructure is systematically studied. The results show that the heterostructure is a direct z-scheme heterostructure, and the photocatalytic performance is better than that of MoSTe and GeC monolayers. [Display omitted] • MoSTe/g-GeC heterostructure is a direct Z-scheme heterostructure, which is suitable for photocatalytic water splitting. • MoSTe/g-GeC heterostructure has excellent absorption coefficient (9.8 × 104 cm−1) in the visible and ultraviolet ranges. • The bandgap of MoSTe/g-GeC heterostructure can change from indirect bandgap to direct bandgap under partial strain. [ABSTRACT FROM AUTHOR]

Context: 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a typical insensitive energetic material. It can be used in explosive formulations, such as PBX-9502 and LX-17-0. TATB is an intriguing and unusual explosive for another reason: it crystallizes into a wide array of planar hydrogen bonds, forming a graphite-like layered structure. Therefore, TATB is one of the important research objects, and its surface structure needs to be deeply understood. In this research work, the electronic and energetic properties of TATB (001) surface are explored. Methods: In this paper, the structural, electronic, energetic properties and impact sensitivity of TATB (001) surface structure at 0 and −3 GPa along with x-axis were calculated in this study using the first-principles calculations. The calculations in this paper are performed in the CASTEP code, which is based on the density functional theory with the first-principles calculation method using the plan-wave pseudopotential approach. The exchange-correlation interaction was adopted by the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional. The DFT-D method with the Grimme correction accurately models van der Waals interactions. To model the surface structures of TATB, the planar slab method was employed. We constructed TATB (001) periodic slabs including three layers with a 15-Å vacuum layer. [ABSTRACT FROM AUTHOR]

Hu et al. reported the hydrogen storage properties of Sc 2 C and Ti 2 C based MXene phases utilizing density functional theory (DFT) as implemented in the CASTEP code [1, 2]. Based on such calculations, the authors suggest that the MXenes should be a new family of potential hydrogen storage media. Their results claim a maximum hydrogen storage capacity of 9.0 wt% with an average binding energy of 0.164 eV/H 2 in Sc 2 C MXene indicating Kubas-type interaction between H 2 and the MXene. These investigations are of prime importance since they provide insight about further applications of MXenes for hydrogen storage. In these calculations they have used local density approximation (LDA) to estimate the adsorption energies. However, binding energies for H 2 with the MXene phases mentioned above obtained from more accurate calculations based on Generalised Gradient Approximation (GGA) and calculation including dispersion correction (GGA + vdW) show very weak binding energy (∼ 0.064 e V / H 2 ) suggesting weak physical interactions between H 2 and the MXene phases. Our accurate DFT calculations predict that these MXene phases are not suitable for hydrogen storage at realistic conditions. So we conclude that appropriate exchange-correlation functional should be used to extract hydrogen adsorption energies in nano-phases to describe their hydrogen storage properties reliably. [ABSTRACT FROM AUTHOR]

The synthesis of a novel spirooxazine (1-benzyl-3,3-dimethylspiro[indoline-2,3′-naphtho [2,1-b] [1,4] oxazine, BSP-SP) was developed as a colorimetric probe for the quantitative analysis of Fe2+ and Pb2+ in water samples. The device is based on a microfluidic paper-based analytical device (μPAD). BSP-SP was characterized by various techniques, e.g. single-crystal X-ray diffraction (SC-XRD) and time-dependent density functional theory (TD-DFT). In addition, the density functional theory (DFT) allowed us to understand better the adsorption of Fe2+ and Pb2+ over other cations adsorption on the BSP-MO structure. The structural isomerization of BSP-SP occurs as an open-form merooxazine (BSP-MO), which acts as a ligand to form Fe2+/BSP-MO and Pb2+/BSP-MO complexes. We observed these complexes under UV irradiation as having a light blue coloration. The μPADs were also proposed as detection platforms to maintain photostability and photochromic efficiency and extend the lifetime of the spirooxazine. Under optimal conditions, the developed μPAD enables rapid and sensitive quantitative analysis of Fe2+ at pH 6 and Pb2+ at pH 11. The limits of detection (LOD) were 0.036 mg L−1 for Fe2+ and 0.152 mg L−1 Pb2+. Overall, the developed sensors, particularly the μPADs, promise the practical analysis of Fe2+ and Pb2+ in water samples. [Display omitted] • Our novel spirooxazine (BSP) was successfully synthesized as colorimetric probe. • BSP-coated μPAD was illustrated to enhance photochromic efficiency. • This method features selectivity toward Fe2+ and Pb2+ determination. [ABSTRACT FROM AUTHOR]

• Electrochemically modified graphite paper is used as electrode substrate. • Molecular interactions of 3-MCPD on polymer was computationally analyzed. • The sensor surface shows a uniform coating Pt@PB Nanoparticles. • MIP/Pt@PB/EM-GP has important application prospects in future detection research. In this study, a molecularly imprinted polymer (MIP) electrochemical sensor based on electrochemically modified graphite paper (EM-GP) was developed for the detection of 3-MCPD for the first time. To this end, Prussian blue (PB) was electrodeposited on EM-GP to yield uniformly distributed PtNPs. The successful preparation of Pt@PB/EM-GP was verified by SEM, Raman spectroscopy, XRD, XPS, and EDS. MIP was then prepared by CV electropolymerization with template molecules (3-MCPD), and density functional theory (DFT) at M06-2X/6–31 + g (d,p) level was used to calculate the molecular-level interaction between 3-MCPD and MIP. Under the optimum conditions, the dynamic linear range of the sensing platform varied from 1 × 10-8 mol/L to 5 × 10-5 mol/L with a detection limit estimated to 5 × 10-9 mol/L (S/N = 3). Overall, these findings look promising for the construction of selective and quick detection platforms of 3-MCPD in food samples. [ABSTRACT FROM AUTHOR]

The research presented in the paper concerns the elastic properties of struvite. The article combines theoretical and experimental research. Experimental studies were carried out on struvite single crystals grown in sodium metasilicate gel by single diffusion. This unique method leads to obtaining crystals of sufficiently large size to conduct, for the first time, experimental measurement of elastic properties of monocrystalline struvite. Using the nanoindentation method, the Ez = 29.1 ± 0.7 GPa value of the component of Young's modulus was determined for a struvite single crystal. In addition, the elastic constants C11, C22, and C33 were determined using micro-Brillouin spectroscopy. Theoretical calculations of the abovementioned properties have been carried out by employing density functional theory methods. Scaling of the theoretical elastic constants leads to obtaining good agreement with the experimental values. Values of the Ex and Ey components of the Young's modulus, not available from the experimental nanoindentation technique, have been determined theoretically as 23 GPa and 27 GPa, respectively. Differences in the values of elastic components and Young's modulus components are related to the layered crystal structure of struvite and directional character of the hydrogen-bonding pattern. [ABSTRACT FROM AUTHOR]

• 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]