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Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept, solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models. Herein, by taking the case study of nucleophilic addition reaction in aqueous solution, we extend the proposed multiscale reaction density functional theory (RxDFT) method to investigate the intrinsic free energy profile and total free energy profile, and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution. The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation. Meanwhile, the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase. In addition, we investigate the solvent effect on the reactions occurred near solid–liquid interfaces. It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10 A distance to the substrate surface owing to the decrease of hydration free energy at the solid–liquid interface.

The transformations of CO2 molecules into valuable products are of increasing interest due to the negative impact of anthropogenic CO2 emissions on global warming. The CO2-to-methanol hydrogenation is an economically profitable reaction of carbon fixation, but it still steps away from widespread industrialization because of the lack of efficient and selective catalysts. Recently, single-atom alloy (SAA) catalysts have been developed to work remarkably in CO2 hydrogenation reactions. Doping isolated single atoms into metallic catalyst can dramatically alter the catalytic performance of the host. We have performed a screening discovery on Ru and 6 RuX (X = Fe, Co, Ni, Cu, Ir and Pt) SAAs using density functional theory (DFT) computations. We considered 13 possible elementary reactions in 4 possible reaction pathways on Ru and all RuX surfaces. In the computed mechanisms, we found that the formation of *H2COOH and *HCOO intermediates plays a critical role in determining catalysts’ activities. Doping Co and Pt isolated single atoms into Ru surface can thermodynamically and kinetically facilitate these intermediates formation processes, eventually promoting the production of methanol. The combination of weak binding and enhanced charge redistribution on RuCo and RuPt surfaces give them improved catalytic activities over pure Ru. This work will ultimately facilitate the discovery and development of SAAs for CO2 to methanol, serving as guidance to experiments and theoreticians alike.

We present a study of the structure and differential capacitance of electric double layers of aqueous electrolytes. We consider electric double layer capacitors (EDLC) composed of spherical cations and anions in a dielectric continuum confined between a planar cathode and anode. The model system includes steric as well as Coulombic ion-ion and ion-electrode interactions. We compare results of computationally expensive, but “exact” , Brownian Dynamics (BD) simulations with approximate, but cheap, calculations based on classical Density Functional Theory (DFT). Excellent overall agreement is found for a large set of system parameters, including variations in concentration, ionic size- and valency-asymmetries, applied voltages and electrode separation, provided the differences between the canonical ensemble of the BD simulations and the grand-canonical ensemble of DFT are properly taken into account. In particular, a careful distinction is made between the differential capacitance $$C_N$$ C N at fixed number of ions and $$C_\mu $$ C μ at fixed ionic chemical potential. Furthermore, we derive and exploit their thermodynamic relations. In the future these relations will also be useful for comparing and contrasting experimental data with theories for supercapactitors and other systems. The quantitative agreement between simulation and theory indicates that the presented DFT is capable of accounting accurately for coupled Coulombic and packing effects. Hence it is a promising candidate to cheaply study room temperature ionic liquids at much lower dielectric constants than that of water.

This paper describes the spectroscopic (FT-IR and UV–Visible), electronic, structural, vibrational properties of celecoxib compound using density functional theory. The optimized geometry structure of the titled molecule is explained by the method of B3LYP with 6–31 + G (d, p) basis set. We found that the simulated optimized geometry of the titled molecule is simulated to the experimental ones. The infrared spectrum of celecoxib compound is represented in the present work. The computational information about the organic molecule can be explained by the charge transfer properties, which is a computational tool for the precise quantum chemical calculations of space charge density distribution and HOMO-LUMO states. The transition states of celecoxib compound have explained by the time-dependent density functional theory (TD-DFT) which is observed by the UV–visible spectrum. Docking research [1] is a modeling method, with the help of docking method we can find out new drug and chemical behavior of the drug which is useful in the application purpose of the drug, the interaction between protein and legends provides the information of the binding energy and physical parameter like partition function, free energy, internal energy, entropy.

Na0.5(Bi3/4RE1/4)0.5TiO3 (RENBT, RE = Nd, Gd, Dy, and Ho) compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave (FP-LAPW) method based on the spin-polarized density functional theory implemented in the WIEN2k code. Combined charge density distribution and Ti K-edge X-ray absorption spectra revealed that the RENBT compositions with high polarization values were accompanied by a higher TiO6 distortion, DyNBT, and NdNBT compounds. The effect of the rare-earth elements on the polarization were confirmed experimentally with the collection of the hysteresis loops. The investigation of the electronic properties of the compounds highlighted the emergence of a magnetization owing to the 4f orbital effect of the rare-earth elements. Besides, the investigation of the chemical ordering showed a short-range chemical ordering for the pure composition and an increased A-site disorder for dysprosium doped NBT system. The increased disorder may speak for increased relaxor properties in the RE doped compositions.

Theoretical and experimental investigations on the molecular structure of 2-amino-5-chloro-3-nitropyridine (2A5Cl3NP) are presented. The molecular equilibrium geometry of the title molecule is fully optimized. Quantum chemical calculations of the HOMO-LUMO energies, energy gap (ΔE), electron negativity (χ), and chemical potential (μ), global hardness (ƞ), and global softness (S) are calculated for the title molecule. The title compound has a low softness value (0.2770) and the calculated value of electrophilicity index (7.7250) describes the biological activity. The stability and charge delocalization of the title molecule are studied by Natural Bond Orbital Analysis (NBO), Non-Linear Optical (NLO) behaviour in terms of first order hyperpolarizability, dipole moment, anisotropy of polarizability are accounted. The computed values of dipole moment (μ) for 2A5Cl3NP molecule is 3.0173 Debye, polarizability (α) is 1.6017 × 10–23esu, hyperpolarizability (β) is 5.08173 × 10–30esu. The high β value and non-zero value of μ indicate that the title compound might be a good candidate for NLO material. The strength of the interaction between electron donors and electron acceptors is measured by the magnitude of energy of hyper conjugative interactions E (2). The second-order Fock matrix is calculated to study the donor–acceptor interactions in NBO analysis.

The role of additional ternary alloying elements on the performance of stationary TiFe-based hydrogen storage alloys was investigated based on first-principles density functional theory calculations. As a basic step for examinations, the site preference of each alloying element in the stoichiometric and non-stoichiometric B2 TiFe compounds was clarified considering possible anti-site defects. Based on the revealed site preference, the effect of various possible ternary elements on the hydrogen storage was examined by focusing on the formation enthalpies of TiFeH and TiFe H 2 hydrides, which were closely related to the change in the location of plateaus in the pressure−composition−temperature curve. Several physical properties such as the volume expansion due to hydride formation were also examined to provide additional criteria for selecting optimum alloying conditions in future alloying design processes. Candidate alloying elements that maximize the grain boundary embrittlement due to the solute segregation were proposed for the enhanced initial activation of TiFe-based hydrogen storage alloys.

Most of the properties of epoxy resins are tied to their degree of cross-linking, making understanding the reactivity of different epoxy systems a crucial aspect of their utilization. Here, epoxy-amine reactivity is studied with density functional theory (DFT) at various cut-off levels to explore the suitability of the method for estimating the reactivity of specific epoxy systems. Although it is common to use minimal structures in DFT to reduce computational cost, the results of this study highlight the important role of hydrogen bonding and other noncovalent interactions in the reactivity. This is a promising result for differentiating the most probable reactive paths for different resin systems. The significance of amine groups as a potential source of catalyzing H-bonds was also explored and, while not quite as effective as a catalyst as a hydroxyl group, a clear catalyzing effect was observed in the transition state energies. Unfortunately, the added complexity of a more representative reactive system also results in increased computational cost, highlighting the need for proper selection of structural cutoffs. publishedVersion

The suite of LED phosphors M2Si5N8:Eu2+ (M = Ca, Sr, Ba) emerged as indispensable solid-state light sources for the next-generation lighting industry and display systems due to their unique propert...

V2CO2 MXene Supported Sc or Mn single atoms are expected to serve as the cost-effective bifunctional catalysts for fuel cells due to its high catalytic activity.

In the field of volatile organic compounds (VOCs) pollution control, adsorption is one of the major control methods, and effective adsorbents are desired in this technology. In this work, the density functional theory (DFT) calculations are employed to investigate the adsorption of typical VOCs molecules on the two-dimensional material borophenes. The results demonstrate that both structure of χ3 and β12 borophene can chemically adsorb ethylene and formaldehyde with forming chemical bonds and releasing large energy. However, other VOCs, including ethane, methanol, formic acid, methyl chloride, benzene and toluene, are physically adsorbed with weak interaction. The analysis of density of states (DOS) reveals that the chemical adsorption changes the conductivity of borophenes, while the physical adsorption has no distinct effect on the conductivity. Therefore, both χ3 and β12 borophene are appropriate adsorbents for selective adsorption of ethylene and formaldehyde, and they also have potential in gas sensor applications due to the obvious conductivity change during the adsorption.

Alkali metal potassium is conducive to structure promotion and electronic modulation in metal oxides. Here, K species was successfully introduced into α-MnO2 via in situ synthesis (Pre-K/MnO2) and hydrothermal impregnation method (Post-K/MnO2) with target to boost the low-temperature reactivity and deep destruction efficiency for toluene oxidation. Results reveal that Post-K/MnO2 possesses the highest catalytic activity with toluene (1000 ppm) totally mineralized at just 258 °C, achieving over 70 °C of temperature reduction than that of Pre-K/MnO2. K specie shows obvious charge transfer balance ability in MnO2, forming MnO6-K-MnO6 bridging bond and leading to more uniform energy of Mn-O bonds. High electron density of K+ can promote the activation of oxygen molecules, resulting in a better catalytic performance of toluene. Abundant Bronsted acid sites are beneficial for toluene adsorption and regeneration of hydroxyl on the surface, which promote the degradation of intermediates during toluene oxidation. Moreover, Post-K/MnO2 shows satisfied catalytic performance under different space velocities and initial concentrations and humid condition. Density functional theory (DFT) calculation revealed the situation of oxygen vacancy and toluene/oxygen adsorption energy in catalysts with different K doping locations. Results showed that the adsorption energy is stronger when K located in large tunnel (0.46 × 0.46 nm), and it is easier to form oxygen vacancy while K entered the small tunnel (0.33 × 0.33 nm). The present work paves new insights into the designing of efficient transition metal oxide catalyst for VOC deep purification.

A carbon quantum dot-based chitosan hydrogel was prepared in this work as a fluorescence sensor for the selective sensing of Hg2+ ions. Among the eight tested metal ions, the prepared hydrogel exhibited remarkable sensing selectivity and sensitivity toward Hg2+. The results demonstrated that a prominent fluorescence quenching at 450 nm was observed in the presence of Hg2+ with a linear response range of 0-100.0 nM and an estimated limit of detection of 9.07 nM. The as-prepared hydrogel demonstrates pH-dependent fluorescence intensity and sensitivity. The highest fluorescence intensity and sensitivity were obtained under pH 5.0. The excellent sensing selectivity could be attributed to a strong interaction between the hydrogel film and Hg2+ ions to form complexes, which provokes an effective electron transfer for fluorescence quenching. Results from density functional theory (DFT) calculation confirm that the interaction energies (ΔIE) of the hydrogel with three toxic metal ions (Hg2+, Cd2+, and Pb2+) are in the following order: Hg2+ > Cd2+ > Pb2+.

Quantum chemical and theoretical calculations were carried out in the present study of some thiaozole derivatives. Relationship between electronic parameters of thiaozole derivatives 5-benzylidene-2,4-dioxo tetrahydro1,3-thiazole (5-BDT) 5-(4′-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5IPBDT), 5-(3′-thenylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-TDT) and 5-(3′,4′dimetoxybenzylidene)-2,4-dioxotetrahydro-1,3-thiazole (5-MBDT) and corrosion inhibition efficiency have been investigated by the Hartree-Fock (HF) and Becke, 3-parameter, Lee-Yang-Parr (B3LYP), M06-2X method with 3-21G, 6-31G, and sdd basis set. All calculations have been performed using the Gaussian 09W suite of programs. The properties most relevant to their potential action as corrosion inhibitors: EHOMO, ELUMO, ΔE (HOMO-LUMO energy gap), electronegativity (χ), chemical potential (μ), chemical hardness (η), electrophilicity (ω), nucleophilicity (e), global softness (σ) and proton affinity (PA) have been studied.

This research was funded by the Latvian Council of Science grant LZP-2018/2-0083. Institute of Solid State Physics, University of Latvia, as the Center of Excellence, has received funding from the European Union?s Horizon 2020 Framework Program H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under Grant Agreement No. 739508, project CAMART2., On the basis of time-dependent density functional theory (TD-DFT) we performed first-principle calculations to predict optical properties and transition states of pristine, N-and S-doped, and N+S-codoped anatase TiO2 nanotubes of 1 nm-diameter. The host O atoms of the pristine TiO2 nanotube were substituted by N and S atoms to evaluate the influence of dopants on the photocatalytic properties of hollow titania nanostructures. The charge transition mechanism promoted by dopants positioned in the nanotube wall clearly demonstrates the constructive and destructive contributions to photoabsorption by means of calculated transition contribution maps. Based on the results of our calculations, we predict an increased visible-light-driven photoresponse in N-and S-doped and the N+S-codoped TiO2 nanotubes, enhancing the efficiency of hydrogen production in water-splitting applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. The article is published under the CC BY 4.0 license., Latvian Council of Science grant LZP-2018/2-0083; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.

Polymer self-consistent field theory techniques are used to find radial electron densities and total binding energies for isolated atoms. Quantum particles are modelled as Gaussian threads with ring-polymer architecture in a four dimensional thermal-space, and a Pauli potential is postulated based on classical excluded volume implemented in the thermal-space using Edwards/Flory-Huggins interactions in a mean-field approximation. Other approximations include a Fermi-Amaldi correction for electron-electron self-interactions, a spherical averaging approximation to reduce the dimensionality of the problem, and the neglect of correlations. Polymer scaling theory is used to show that the excluded volume form of Pauli potential reduces to the known Thomas-Fermi energy density in the uniform limit. Self-consistent equations are solved using a bilinear Fourier expansion, with radial basis functions, for the first eighteen elements of the periodic table. Radial electron densities show correct shell structure, and the errors on the total binding energies compared to known binding energies are less than 9% for the lightest elements and drop to 3% or less for atoms heavier than nitrogen. More generally, it is suggested that only two postulates are needed within classical statistical mechanics to achieve equivalency of predictions with static, non-relativistic quantum mechanics: First, quantum particles are modelled as Gaussian threads in four dimensional thermal-space and, second, pairs of threads (allowing for spin) are subject to classical excluded volume in the thermal-space. It is shown that these two postulates in thermal-space become the same as the Heisenberg uncertainty principle and the Pauli exclusion principle in three dimensional space., Comment: 23 pages, 3 figures, 1 table

Highly efficient, stable and cost-effective electrocatalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) have been pursued for several decades. Herein, by employing density functional theory (DFT), a wide range of transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Ir, Pt and Au) atoms anchored on antimonene (Sb monolayer) with a single Sb vacancy as single-atom catalysts (SACs) were investigated for their HER, OER and ORR performance. The results indicate that the defective Sb monolayer can be stable. Some TM@Sb monolayers show excellent stability and good electrical conductivity, beneficial for electron transfer during electrocatalytic reactions. The Ir@ and Pt@Sb monolayers exhibit excellent HER performance, both with about -0.01 eV of ΔG*H. The d band centre of the TM@Sb monolayer can be used to describe the binding strength between substrates and intermediates directly. The best OER electrocatalyst is the Pt@Sb monolayer, which shows an overpotential (ηOER) of 0.48 V. In contrast, the best ORR electrocatalyst is the Ag@Sb monolayer with an ηORR of 0.50 V, followed by Pd@, Rh@, Cd@ and Pt@Sb monolayers. Compared with pristine antimonene, only the noble metal atom could improve its OER and ORR performance effectively, and the Pt@Sb monolayer can be a trifunctional electrocatalyst for the HER/OER/ORR. Therefore, our calculations highlight a new type of SAC based on antimonene, which can be useful for energy conversion and storage.

Various feedstocks such as natural gas, glycerol, biomass, methanol, ethane, and other hydrocarbons can be reformed to generate hydrogen as a viable alternative source of renewable energy. Also, hydrogen is generated via other processes not associated with reforming including electrolysis, thermolysis, and photolysis. The reforming of the different feedstock for hydrogen reaction generally requires the utilization of heterogeneous catalysts to speed up the reactions and reduce the energy used up in the reaction. Experimental studies provide an understanding of the reaction mechanism and the nature of the reactants and products of the reaction. Computational studies involving density functional theory provide even greater insights into these reactions. Its combination with machine learning provides huge potentials for the study and discovery of technologies for hydrogen production but remains underutilized. The use of both computational techniques has widely been adjudged as the most economical and precise means of screening multiple catalysts in the heterogeneous reactions involved in hydrogen production processes. This paper reviews the application of density functional theory and machine learning in thermochemical reactions associated with the production of hydrogen. It also highlights the state-of-the-art computational methodologies employed in the design of hydrogen production technologies such as methane pyrolysis, steam methane reforming, dry reforming of methane, and other reforming processes for hydrogen production. The current progress and knowledge gaps in the research and development of hydrogen production technologies from a computational point of view are also discussed.

The synergy effect of CuCl2 and FeCl3 impregnated into fly ash on mercury removal was investigated by experiment and density functional theory. The mercury removal efficiency of fly ash impregnated with a mixture of CuCl2 and FeCl3 was higher than that by single one of them. When the mass ratio of CuCl2 to FeCl3 was 3:1 and the sample temperature was between 140 °C and 160 °C, its mercury removal efficiency was the highest. Cu2+ contributes more than that of the Fe3+ in the mercury removal process. The density functional theory was applied to calculate their adsorption energy, electron transfer and energy barrier. The coexistence of Cu and Fe enhances the non-uniform charge distribution between the Cu, Fe and Cl. This non-uniform charge distribution accelerates the charge transfer of Hg0, which leads to a stable adsorption for Hg0. The synergistic effect of CuCl2 and FeCl3 can reduce the energy barrier during the Hg0 removal. This work provides an efficient approach for utilizing fly ash to remove Hg0 in coal combustion flue gas.

In this work, we present a software package in Python for high-throughput first-principles calculations of thermodynamic properties at finite temperatures, which we refer to as DFTTK (Density Functional Theory Tool Kit). DFTTK is based on the atomate package and integrates our experiences in the last decades on the development of theoretical methods and computational software. It includes task submissions on all major operating systems and task execution on high-performance computing environments. The distribution of the DFTTK package comes with examples of calculations of phonon density of states, heat capacity, entropy, enthalpy, and free energy under the quasi-harmonic phonon scheme for the stoichiometric phases of Al, Ni, Al3Ni, AlNi, AlNi3, Al3Ni4, and Al3Ni5, and the fcc solution phases treated using the special quasirandom structures at the compositions of Al3Ni, AlNi, and AlNi3., 50 pages, 18 figures

The water gas shift reaction is an important reaction for H2 production in various industrial applications. The presence of CaO can promote the reactivity of the water gas shift reaction without any catalysts, but the enhancement mechanism of CaO in this reaction is difficult to determine just by the experiment. In this work, the water gas shift reaction along four possible pathways on the CaO surface were studied by density functional theory (DFT) analysis. The energy barriers along the pathways were analyzed to determine the most possible reaction pathway and role of the CaO surface. The DFT calculation results show that the WGS reaction is more prone to proceed along the redox-a pathway probably: H2O dissociates into hydroxyl and atomic H spontaneously when H2O and CO co-adsorb on the CaO surface, then the hydroxyl continues to dissociate and CO is oxidized by the generated atomic O. Afterwards, H2 molecule generates from two atomic H, and then CO2 adsorbs and H2 desorbs simultaneously on the CaO surface. The CaO surface enables the spontaneous dissociation of H2O, which is the rate-limiting step of WGS reaction. The generation of CO2 is facilitated, and the energy barrier is reduced from 2.304 to 0.757 eV on the CaO surface. Besides, the formation of CO32− on the surface avoids the energy barrier for CO2 desorption, while the CO2 also occupies the active site and reduces the enhancement of CaO on WGS reaction. The calculation result reinforces the comprehension on the mechanism of CaO on WGS reaction.

Strong interactions between loading drugs and nanocarriers contribute greatly to the high loading capacity while bringing about the problems on effective drug release. To solve this dilemma, we develop a density functional theory (DFT)-guided drug loading strategy to construct a dismountable nanoplatform for sensitized tumor-homing thermotherapy. DFT, a kind of computational method, is used to screen out a heat shock protein90 (HSP90) inhibitor, geldanamycin (GDM), that highly matched the structure of nanocarriers, thus providing a high drug loading efficiency (~ 42%). Of special note, GDM could be effectively released inside tumor cells because the isoelectric points of cancer cell membrane (CCM) and polydopamine (PDA) are both around pH 4.0 ~ 5.0, which could exactly match with the acidic environment of endo/lysosome. The CCM envelope enables self-targeting of PDA/GDM@CCM to the source cancer cells and homologous tumors while effectively inhibiting recognition and clearance by macrophages. Efficient photothermal ablation is attributed to the efficient suppression of tumor heat resistance by GDM and precise selection of the best matched tumor type by using The Cancer Genome Atlas (TCGA). This DFT-guided drug loading strategy points out a new avenue for optimization of drug-loading into nanocarriers, and ultimately contributes to the high drug availability and excellent curative effect.

Arsenic species (As4, As2 and AsH3) released during the coal gasification process can cause significant damage to human health and the environment. In this work, the adsorption capability of Ti-doped graphene for As4, As2 and AsH3 was investigated through density functional theory calculations. The optimized adsorption configuration, adsorption energy and electronic structure were analyzed in detail. The results showed that a single vacancy graphene-based substrate with three nitrogen atoms doping (Ti/SV-N3) was a promising adsorbent for the simultaneous removal of arsenic species, but the adsorption behavior of As4, As2 and AsH3 were different. The adsorption of As4 on Ti/SV-N3 belonged to the dissociation model, and its adsorption process was dominated by both electron transfer and orbital hybridization. As2 and AsH3 were adsorbed on the substrate surface in the form of molecules. In the adsorption systems of As2 on Ti/SV-N3, ionic and covalent bonds were both formed, similar to As4. For AsH3 adsorbing on the substrate, the adsorption systems of Ti/GS all exhibited weak chemisorption, which was mainly controlled by ionic interactions. In addition, instead of the d-band center, the relationship between the adsorption activity and the electronic structure can be explained by the partial d-band center, especially for the adsorption system of As2 on Ti/GS. Furthermore, the Fermi softness can be used to describe the adsorption activity of Ti/GS.

Compound-specific isotope analysis (CSIA), position-specific isotope analysis (PSIA), and computational modeling (e.g., quantum mechanical models; reactive-transport models) are increasingly being used to monitor and predict biotic and abiotic transformations of organic contaminants in the field. However, identifying the isotope effect(s) associated with a specific transformation remains challenging in many cases. Here, we describe and interpret the position-specific isotope effects of C and N associated with a SN2Ar reaction mechanism by a combination of CSIA and PSIA using quantitative 13C nuclear magnetic resonance spectrometry, and density-functional theory, using 2,4-dinitroanisole (DNAN) as a model compound. The position-specific 13C enrichment factor of O-C1 bond at the methoxy group attachment site (eC1) was found to be approximately -41‰, a diagnostic value for transformation of DNAN to its reaction products 2,4-dinitrophenol and methanol. Theoretical kinetic isotope effects calculated for DNAN isotopologues agreed well with the position-specific isotope effects measured by CSIA and PSIA. This combination of measurements and theoretical predictions demonstrates a useful tool for evaluating degradation efficiencies and/or mechanisms of organic contaminants and may promote new and improved applications of isotope analysis in laboratory and field investigations.

Catechol (1, 2 dihydroxybenzene) is an industrial feedstock and acts as one of the environmental pollutants causing various health issues like skin irritation, eye damage etc. It is a challenge to the researchers to design efficient sensing material for catechol. Employing the advanced Density Functional Theory (DFT) simulation, we have probed the catechol sensing capabilities of pristine and metal-decorated 2D dichalcogenide MoS2. We have presented the charge transfer as well as bonding means of catechol on pure and metal-decorated MoS2 through Bader charge analysis and orbital interaction. DFT results predict Ti-decorated MoS2 to be a promising catechol sensing material due to higher binding energy of catechol on that. It is found that more charge transport from O 2p orbital of catechol to metal d orbital and shorter O-Ti bond length, stronger bonding through p-d hybridization happens for Ti-decorated MoS2. The stability of the structure has been inspected through ab-initio Molecular Dynamics calculations at 300 K and the structure was found to be stable. Based on the presented conjectural predictions, we put forward Ti-decorated MoS2 being a possible nanomaterial for catechol-detection.

In this work, based on the first-principles method of density functional theory (DFT), the adsorption and dissociation paths of sulphide gas molecules on pure, vacancy-defective, Ni-doped and Cr-doped γ-Fe(1 1 1) surfaces have been studied systematically. The results show that H2S, COS, CH3SH can be spontaneously adsorbed on these four surfaces. Significant adsorption properties, changes in molecular structure and charge transfer indicate that chemical adsorption has taken place. The calculation results of the density of states show that the electronic orbitals between the sulphide molecules and the substrate surface are hybridized, indicating the formation of new chemical structures between them. Meanwhile, the chemical bonds of the three sulphide molecules are easy to break during the adsorption process, and the products are adsorbed on the surface in a more stable form. This work can provide theoretical guidance for anticorrosion and material selection of natural gas pipeline.

In this study, we explored the adsorption of three industrial toxic gases (Cl2, NO2, and NH3) on Ag3-WSe2 monolayers using density functional theory calculations. The possible application of Ag3-WSe2 as an industrial toxic gas sensor and adsorbent is discussed through our analyses of the density of states, adsorption energy, band structures, and charge transfer of the three gas molecules absorbed on the Ag3-WSe2 and WSe2 monolayers. The results show that the Ag3-WSe2 monolayer exhibits better adsorption for these gas molecules than the WSe2 monolayer. Thus, Ag3-WSe2 might be a candidate material for the detection of industrial toxic gases. In addition, it provides guidance for the further investigation of transition metal cluster-doped WSe2 monolayers for gas detection.

TiO2/rGO and TiO2/MWCNT electrode materials have been synthesized by the hydrothermal method. The synergetic effect of TiO2/rGO electrode enhances the specific capacitance to a value of 558F/g at 1 A/g and having cyclic stability of 100% for up to 5000 cycles. The fabricated symmetrical supercapacitor device shows the maximum energy density of 14 W h/kg and power density of 9.6 kW/kg at 0.5 A/g and 32 A/g current density, respectively. TiO2/rGO electrode shows excellent cyclic stability leading to its claim as the potential electrode in the energy storage devices. From density functional theory calculations, we observed an enhanced density of states close to Fermi level for TiO2/rGO structure and charge transfer from 2p orbital of rGO to Ti 3d orbital of TiO2 signifying the enhancement in conductivity of the hybrid structure. Furthermore, the computed quantum capacitance has been increased for TiO2/rGO electrode which qualitatively supports our experimental findings.

Photocatalytic water splitting for hydrogen evaluation as a green approach for energy production has received extensive attention from researchers. The strongly reducing single layer MoSe2 and oxidizing WO3(0 0 1) were constructed as a MoSe2/WO3(0 0 1) heterojunction (MWH). The electronic structure and optical properties of the MWH were calculated and analyzed using the density functional theory (DFT) to reveal the internal causes of the photogenerated carrier migration path and the photocatalytic mechanism. The electronic structure and optical absorption analysis showed that MoSe2 and WO3 contributed to the valence band maximum (VBM) and conduction band minimum (CBM) of MWH, respectively, narrowing the bandgap and broadening the optical absorption range. The energy band bending results indicated that the MWH was a Z-scheme photocatalytic heterojunction. Through the segregation of the oxidation (WO3) and reduction sites (MoSe2), photogenerated electrons and holes could be separated, and the formation of a built-in electric field inhibited the recombination of photogenerated carriers. Given that the MWH exhibited superior oxidation (3.302 eV) and reduction (−0.128 eV) properties, it has great potential for applications in the field of photocatalytic hydrogen production.

Two-dimensional materials, known as 2D materials, have attracted increasing interest in recent years. 2D semiconductors can potentially be used in a multitude of applications in flexible electronics and atomic applications. In this framework, we investigate the structural, vibrational, and electronic properties of new 2D SrFCl and SrFBr monolayers, employing density functional theory and beyond with GW approximation. We have obtained these monolayers are dynamically stable since there are not imaginary modes in their phonon dispersion, confirming the stability of the two-dimensional form of these compounds. Our GW results show that the bandgap energy of SrFCl monolayer is significantly larger than the bandgap of PbFCl monolayer (6.38 eV with GW) by ∼ 1.17 eV. Further, the bandgap energy value obtained for the SrFBr monolayer is larger than the bandgap of the PbFI sheet (6.64 eV with GW) by ∼ 0.62 eV.

Carbon capture, utilization, and storage (CCUS) has become a promising approach for relieving CO2 effects on the environment. Moreover, CO2 absorption by phase-splitting solvents with a low regeneration energy has the potential for industrial CO2 capture. In this work, ionic logP of the product amine-CO2 was modeled to predict new phase-splitting solvents at the molecule level. The density functional theory method was used for structure calculation and descriptor generation. The genetic function approximation method was used for mathematical regression. The symmetry-adapted perturbation theory and reduced density gradient method were introduced to detect interaction mechanisms between ions and solvents. Furthermore, low-ion solubility tended to appear in long-chain alcohols, branched or ring structures, and aprotic solvents. A linear the demarcation line of biphase and monophase over phase-splitting diagram was drawn based on anion logP and cation logP as 0.984 * logPanion + logPcation = − 3.46.

High-concentration formaldehyde-based wastewater causes a serious hazard to the human body and ecosystem. Electro-Fenton technology can be used for the pre-treatment of high-concentration formaldehyde wastewater, but the uneven distribution of free radicals and formaldehyde affects the degradation efficiency of Electro-Fenton. Oxygen-containing functional groups can enhance the adsorption and enrichment of the pollutants near the cathode, thereby improving the degradation efficiency of Electro-Fenton. In this paper, quantum chemical simulation was adopted to study the effects of different oxygen-containing functional groups on the adsorption of formaldehyde on the carbon surface. The results showed that incorporating oxygen-containing functional groups changed the electronic structure of the carbon surface and affected the interactions between formaldehyde and carbon surface. Only the incorporation of certain oxygen-containing functional groups at the edge of the carbon surface could promote the adsorption of formaldehyde. Edge ether group promoted the basal plane adsorption of formaldehyde on the carbon surface by enhancing dispersion interactions. The edge carboxyl group and edge hydroxyl group influenced the edge adsorption of formaldehyde on carbon surface due to the enhancement of electrostatic interactions. The edge pyrone group promoted the edge adsorption of formaldehyde by influencing the dispersion interactions and electrostatic interactions between formaldehyde and the carbon surface.

MXenes have potential as a hydrogen evolution reaction (HER) catalyst based on their large surface area and excellent electrical properties. In this study, the change in HER catalytic properties according to the surface state of Ti2C-based MXene was analyzed theoretically based on first principles calculation. It was confirmed that the reactivity of the surrounding active sites is enhanced by the influence of isolated fluorine. The mechanism of this phenomenon was investigated, focusing on the electron migration and structural changes. In the MXene family, the Ti2C-based MXene best utilized the isolated fluorine effect. It was found that Ti2CO2 functionalized with a small amount of fluorine was superior as a HER catalyst to Ti2CO2 fully functionalized with oxygen, and the optimal proportion of fluorine was 1.5 to 3%.

Using the density functional theory methods with the PBE gradient functional, and taking into account the van der Waals interaction in the basis of localized atomic orbitals, using the CRYSTAL 17 program code, calculations of the structure and elastic constants for MgCO3, ZnCO3, CdCO3 CaCO3 in the calcite structure, CdMg(CO3)2, CaMg(CO3)2, CaZn(CO3)2 in the dolomite structure, BaMg(CO3)2 – norsethite, and CaCO3, SrCO3, PbCO3, BaCO3 in the aragonite structure are calculated. It is shown that the lattice constants, interatomic distances linearly depend on the cation radius RM, and the band gap, atomic charges, overlap populations of electron shells, and crystal density depend on cation electronegativity χM. Elastic compression constants and linear elastic moduli along the c axis are also described by RM. For polycrystalline bulk modulus BH, shear modulus GH, and Young's modulus EH, linear dependences with a good correlation coefficient were obtained: BH (GPa) = 175.95−84.89·RM, GH (GPa) = 87.57−46.05·RM, EH (GPa) = 224.36−103.59·RM. Similar dependences are established for the longitudinal and transverse speeds of sound, the Debye temperature and the coefficient of minimum thermal lattice conductivity. These results can be used to predict the elastic and mechanical characteristics of carbonates with the chemical formula MCO3 and solid solutions based on them.

Twin T-graphene is a new three atomic layer thick two-dimensional carbon allotrope. In the current research, the structural and electronic properties of 3d transition metal (TM) embedded twin T-graphene are studied utilizing density functional theory (DFT) calculations. All 3d TM atoms transfer charge to the neighboring C atoms, and strongly get adsorbed to the sheet. Our findings reveal that the electronic properties of twin T-graphene are modulated by TM adsorption. The twin T-graphene is a semiconductor, while TM decorated twin T-graphene shows different electronic properties depending on the species and concentration of TM atoms. The semiconductor for Sc, Ti, V, Cr, and Zn adsorption, metal for Mn, Cu, and Ni adsorption, and bipolar magnetic semiconductor for Fe and Co adsorption are observed. The energy band gap of TM embedded twin T-graphene sheets with semiconducting properties decreases with increasing the concentration of TM atoms. Our results indicate that TM embedded twin T-graphene can be used in electronic and spintronic devices.

Doping various elements is able to change the structural and electronic properties of two-dimensional aluminum nitride (2D AlN), hence leading to different optical properties. By Density functional theory (DFT) calculation, broken 2D structure and 2pz electron conjugative effects to form intensive covalent bond are observed in C/P co-doped 2D AlN, confirming the variation in structure and electron state. Band gap values of C/P co-doped 2D AlN are drastically reduced due to bonding ability enhancement by C atom, which renders C/P coupling anti-bonding state is pushed to valence band. Optical properties are measured at low energy range. Enhanced optical response at E‖x and E‖y is attributed to the co-doping of C and P, resulting in improved optical conductivity, adsorption ability, refractive N (ω) and reflectivity R (ω). Especially for 2D Al16N13C2P1 modified by 2 C and 1 P atom doped in N sites (2C/1P), nearly three times increase is detected for optical conductivity.

Kilogram-level extraction, modified high-pressure preparative chromatography (MHPPC), and flash preparative chromatography (FPC) were applied to separate condensed arenes (CAs) and heteroatom-containing aromatics (HACAs) from a high-temperature coal tar and its petroleum ether-extractable portion (PEEP). A series of CAs and HACAs were enriched from PEEP via MHPPC. Naphthalene and other 8 arenes were purified with purities of 99.9% and higher than 75%, respectively, by recrystallization and FPC. Density functional theory and molecular dynamics were used to calculate the solvation free energies (SFEs) and the complex intermolecular interactions (IMIAs), respectively, between solvent and solute at the molecular level. The difference in SFE is positively correlated with the number of aromatic rings of each compound. The IMIAs related to the separations include hydrogen bonds, such as >CH2···X (X denotes NH C O···X, and –O–H···X bonds, >CH2···π, >C O···π, –O–H···π bonds, π···π stacking, and van der Waals forces.

GaFeO3 (GFO) is a multiferroic semi-conductor with a wide range of applications such as spintronic devices, sensors, and storage devices. This material is anti-ferromagnetic (AFM) in its ground state. The usual way to overcome the AFM ground state is doping. In this work, we would like to alter the magnetic property of GFO by partial substitution of the Ga atoms with the Zn atoms. The effects on the structural, electronic, and magnetic properties of GFO are investigated by the density functional theory with GGA + U formalism. The Zn concentration was varied in Ga1-x ZnxFeO3 system (x = 0%, 12.5%, 25%, 37.5% and 50%) and named as GFO, GZFO1, GZFO2, GZFO3 and GZFO4 respectively. The structural studies show that the lattice constants, orthorhombic distortion, and cell volume increase upon Zn substitution. Magnetization of the Zn-substituted samples is enhanced compared to the pristine sample. Also a phase transition in the magnetic structure from AFM to ferrimagnetic is observed. And, the electronic investigations show that all samples are half-metallic compounds except 50% Zn-substituted sample which is metallic compound.

Spin-polarized density functional theory calculations with van der Waals correction were applied to investigate the presence of transition metal dopant atoms (Fe, Co, Ni, Pd and Pt) and their respective nitrogen vacancy complexes in the Ti3N2 MXene monolayer as candidate material for hydrogen evolution reaction (HER). We found that the transition metal dopant atoms as well as transition metal vacancy will feasibly form. However, the cation transition metal dopant atoms with nitrogen vacancy complexes and nitrogen vacancy are endothermic except for the PtTi + VN complex, thus would require additional energy to be realized. To evaluate for the HER activity, the Gibbs free energy and adsorption energetics were calculated. We found that the H atom stably bind to the considered surface configurations. However, the Gibbs free energy is far from optimal for the dopant complexes and the pristine Ti3N2 MXene monolayer. All the considered configurations have magnetic metallic ground state with possible application as 2D magnetic system.

Inorganic toxic gases (ITGs) and volatile organic compounds (VOCs) are two kinds of typical hazardous gaseous pollutants harming human health. The removal of them is still an enormous challenge. Based on density functional theory (DFT) calculations in this work, Al-doped Ti2CO2 (ATCO), a single-atom-decorated MXene, is expected to be a more effective adsorbent for these gases than pristine Ti2CO2 (TCO) due to the outstanding adsorption capacity and superb electrical properties. We then shed light on the mechanism of enhanced adsorption by ATCO. The results of Mulliken charge analysis, partial density of states (PDOS) and deformation charge density (DCD) confirm the change of charge distribution on ATCO surface after the decoration of Al atom. Obviously, Al atom can act as a bridge to promote the formation of chemical bonds between the adsorbed gases and ATCO substrate. This work not only provides a promising material for the adsorption of gaseous pollutants, but also explores a new avenue for designing and fabricating MXene-based non-noble metal materials in the area of gas adsorbents.

The molecular adsorption of hydrogen sulfide has been investigated theoretically by using Density Functional Theory for gallium (Ga), germanium (Ge) and boron (B) doped (4,0) single-walled carbon nanotubes (SWCNTs). The method of B3LYP was utilized with basis sets of 6-31G(d,p) and LANL2DZ. Adsorption energy and adsorption enthalpy, HOMO and LUMO energy values, HOMO-LUMO energy gap, chemical hardness, chemical potential, electronegativity and Gibbs free energy values have been evaluated in this study. All doped SWCNT structures have negative Gibbs free energy and adsorption energy values which make these clusters promising for the removal of H2S by adsorption. However, Ge doped SWCNT cluster has the lowest HOMO-LUMO energy gap and chemical potential, highest electronegativity with minimum adsorption energy values when compared to other clusters. Furthermore, it is softer than other metal doped SWCNT clusters due to the lower chemical hardness value.

Pyrolytic tire (PT) chars were first produced from waste car tires (WCT) through carbonization process at 800 degrees C, for different retention times. Then, best PT-char sample by its physicochemical properties (WCT 800(1 h)) was further tested for its ability to adsorb Rhodamine B (RhB) dye from aqueous solutions. Structural characterization of synthesized material showed existence of graphene-based material, with average pore diameter of 22.8 nm and specific surface area of 55.8 m2.g- 1. Obtained carbon material meets specifications of commercial carbon black (CB). The yield of 33.6% of CB recovered has been achieved. Under the optimal conditions, 99.57% of RhB was removed. Adsorption of RhB obeys pseudo second-order model and Langmuir isotherm model. DFT (the density functional theory) was revealed that effective bonding of RhB onto WCT 800 originates from pi-electron interactions with aromatic moieties and chemical (or at least the electrostatic) interactions, between positive nitrogen and electron-rich surface groups.

Atomic layer deposition (ALD) of metals and metal nitrides consist a major portion of the advanced thin film deposition technology owing to their wide applications in the field of the semiconductor industry. In this regard, the ALD of tungsten (W) is one of the vital processes which is mostly studied using WF6 precursor. However, the presence of corrosive fluorine in WF6 restricts its applications due to severe disadvantages like F-contamination and etching of the deposited films and/or the underlying substrate. Therefore, developing F-free W (FFW) precursor to deposit W (and other W-based compounds like WNx) is of significant importance. The current article investigates several possible routes that can give rise to the successful growth of ALD-W or W-based thin films using WCl5 as an FFW precursor. Density functional theory (DFT) simulation was carried out to check the feasibility of the reactions between a reactant and tungsten chloride as well as to predict the composition of the deposited film. The exothermic reactions for ALD of W metal were realized with H, diethylamine borane (DEAB), and dimethylamine borane (DMAB), whereas it was endothermic for H2, triethylaluminum (TEA), trimethylaluminum (TMA), tert-butyl hydrazine (TBH), and NH3. The detailed reaction mechanisms for predicting the growth of tungsten or tungsten compounds were simulated and are helpful to explain the growth of WNxCy by TBH and WCx by TEA. On the other hand, the experimental findings also confirm the W film deposition with H2 plasma and DEAB, between 200 and 300 °C. However, the best quality as-grown W-films (polycrystalline with a resistivity of ~395 µΩ-cm) were obtained only with H2 plasma as a reactant, which shows the largest negative reaction energy (ΔE) in DFT calculation. Further, the Cl content of much below 1 atomic% in the as-grown films deposited with H2 plasma was evident. Additionally, the experimental findings also confirmed the deposition of crystalline-W2N when NH3 was used as a reactant.

The generation of high-valent iron-oxo species via the activation of peroxymonosulfate (PMS) by Fe–N moieties has shown promise for selective degradation of contaminants, but the underlying electron-transfer mechanism remains unclear. To fill this gap, we here investigated the generation of high-valent iron-oxo species using hemin as a model Fe–N moiety–containing activator of PMS and used density functional theory (DFT) calculation to gain mechanistic insights from a molecular level. The results showed that hemin had great reactivity for the target contaminant–bisphenol A degradation; around 100% degradation was achieved after reaction for 30 min. Radicals including hydroxyl radicals, sulfate radicals, and superoxide anion radicals and singlet oxygen did not contribute to the degradation. Instead, FeV = O was the dominant reactive species that was revealed by the generation of dimethyl sulfone from dimethyl sulfoxide oxidation. The selectivity of FeV = O was demonstrated by the negligible inhibitory effects of common anions. The chemical bond and Mulliken charge analyses consistently suggested that the electron transfer from hemin led to the cleavage of O–O bond and the activation of PMS. Although we do not point out the exact pathway for the generation of FeV = O, the results from this study are expected to deepen the understanding of the interaction between PMS and Fe-containing porphyrin materials and the generation of high-valent iron-oxo species.

The present work investigates on structural and chemical studies on 1-Phenyl Sulfonyl Pyrrole(1PSP) using quantum computational methods. The revamped geometric structure and its parameters were obtained through density functional theory (DFT). The electronic absorption transitions were discussed with different solvents were carried out by TD-DFT (Time Dependent Density Functional Theory) method. The IR intensities and Raman activites are tabulated for vibrational wavenunbers and its corresponding PED (Potential Energy Distribution) assignments in percentage were obtained from VEDA4 software. The inter and intra molecular interactions, electrophilic, nucleophilic and chemical reactivity sites are identified by Molecular electrostatic Potential (MEP), HOMO-LUMO (Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital) and GCRD (Global chemical reactivity descriptors). Mulliken atomic charges were discussed with Natural Bond Orbital (NBO) analysis. Thermodynamic property and Non-linear optical deportment of the title compound is also talked about. Besides the electron localization function map, the density of states are also mapped with Multiwfn software, a wavefunction analyzer.

As a promising cathode material, Na3V2(PO4)2F3 (NVPF) has attracted wide attention for sodium-ion batteries (SIBs) because of its high operating voltage and high structural stability. However, the low intrinsic electronic conductivity and insufficient Na ion mobility of NVPF limit its development. Herein, K-doping NVPF is prepared through a facile ball-milling combined calcination method. The effects of K-doping on the crystal structure, kinetic properties and electrochemical performance are investigated. The results demonstrate that the Na2.90K0.10V2(PO4)3F3 (K0.10-NVPF) exhibits a high capacity (120.8 mAh g−1 at 0.1 C), high rate capability (66 mAh g−1 at 30 C) and excellent cycling performance (a capacity retention of 97.5% at 1 C over 500 cycles). Also, the occupation site of K ions in the lattice, electronic band structure and Na-ion transport kinetic property in K-doped NVPF are investigated by density functional theory (DFT) calculations, which reveals that the K-doped NVPF exhibits improved electronic and ionic conductivities, and located K+ ions in the lattice to contribute to high reversible capacity, rate capability and cycling stability. Therefore, the K-doped NVPF serves as a promising cathode material for high-energy and high-power SIBs.

Electrochemical CO2 reduction to higher-value hydrocarbons beyond C1 products has attracted much attention recently. Single-atom catalysts (SACs) are regarded as promising CO2 reduction electrocatalysts. However, most SACs only show activity to C1 products. In this work, we considered the activity and the synergetic effect of dual active sites for metal SACs supported on graphitic carbon nitride (g-C3N4) as CO2 reduction electrocatalysts. Density functional theory (DFT) calculations are employed. First, by using the adsorption energies of CO* on the metal site and that of H* on the nitrogen site as bi-descriptors, we predicted seven out of 14 metal centers have the propensity to generate beyond CO products. To further evaluate the catalyst activity on beyond CO product formation, we established reaction pathways towards ethylene through M/N or M/C. Ru has the best performance (the limiting potential is −0.90 V) by taking M/N as active sites. A dual volcano-shaped plot is built up based on the CO adsorption energies on metal sites, which can be used to indicate whether M/C or M/N shows better performance for a specific metal center. Our work shed light on developing criteria to guide the design of CO2 reduction electrocatalysts with dual active sites.

Due to the water-insoluble nature of Hg0, its oxidization to Hg2+, which is water-soluble, is a viable approach for its effective removal at coal-fired plants using existing flue gas desulfurization (FGD) unit. In this study, the adsorption and oxidation of elemental mercury on an Mn-doped g-C3N4 material were investigated. The spin-polarized density functional theory method was adapted to optimize the geometry structures and then to determine the corresponding electronic structures, while the CI-NEB method was adopted to search for the stable intermediates during the reaction(s). The analysis of energy and project density of states shows that the Mn-g-C3N4 exhibits an excellent affinity to Hg atoms. It is found that it is feasible for Hg atoms to oxidize on the Mn-g-C3N4 surface via two possible E-R paths, but with relatively high energy barriers. This research provides insights into a viable way for mercury removal using O2 as the oxidizing agent.

Electrochemical catalysts for the hydrogen evolution reaction (HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni2P/MoS2 cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni2P and MoS2 improved the catalytic performance for the HER. Compared with pure Ni2P catalyst and MoS2 catalyst, the prepared Ni2P/MoS2 cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide pH range and low onset potential values of 280, 350 and 40 mV in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec−1, respectively. Density functional theory (DFT) was adopted to calculate the hydrogen adsorption free energy (△GH∗). The results showed that the interface between Ni2P and MoS2 reduced △GH∗, which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.

Rely on the density functional theory (DFT) calculation, the catalytic performance of PdxCuy/GDY (x = 1, 2, 3, 4; x + y ≤ 4) for CO oxidative coupling reaction was obtained. The Pdx/GDY (x = 1, 2, 3, 4) are not ideal catalyst for dimethyl oxalate (DMO) formation because by-product dimethyl carbonate (DMC) is easily formed on Pd1/GDY and Pd2/GDY, and high activation energies are needed on Pd3/GDY and Pd4/GDY. Therefore the second metal Cu is doped to regulate the performance of Pdx/GDY (x = 1, 2, 3, 4). Doping Cu not only improve the activity of DMO formation, but more importantly, controlling the ratio of Cu:Pd can effectively regulate the selectivity of DMO. Thus taking into account the activity and selectivity of the reaction for the preparation of DMO by CO oxidative coupling, the Pd1Cu1/GDY and Pd1Cu2/GDY with the activation energies of 105.2 and 99.2 kJ/mol to generate DMO show excellent catalytic activity and high DMO selectivity, which are considered as good catalysts for CO oxidative coupling. The differential charge density analysis shows the decrease in the charge density of metal clusters is an important reason for improving the selectivity of the catalyst.