Density Functional Theory Simulations Research Articles

Investigation of Doping Effects on the Local Electrochemical Activity of Transition Metal Dichalcogenides 2D Materials

AbstractFinding strategies to enhance catalysts’ electrochemical activity is based on controlling the material design. Bidimensional materials (2DM) such as MoS2 are explored as catalysts for the hydrogen evolution reaction (HER). A comprehensive study of the effects of doping 2D materials with transition metals based on theoretical predictions in tandem with experimental investigation correlates the doping type to the changes in the electronic and electrochemical activity. Localized electrochemical maps obtained by scanning electrochemical cell microscopy (SECCM) reveal that Ti‐doping induces a heterogeneous increase in 2H‐MoS2 basal plane electrochemical activity, while Ni‐doping induces a homogeneous decrease. Additionally, Kelvin probe microscopy provides insight into Ti‐doping, showcasing a decline in the 2H‐MoS2 work function, therefore confirming the predictions from density functional theory simulations. In essence, the findings underscore the potential of transition metal coordination on the 2H‐MoS2 surface as an attractive method for locally doping 2D materials with minimal damage to the crystalline lattice, consequently enhancing the electrochemical activity on the material's basal plane.

Cycle-to-cycle switching endurance variability in vertically aligned nanocrystalline molybdenum disulfide: computational insights

We propose a model to depict abrupt transient changes in the endurance test results of a resistive switching device comprising vertically oriented layers of nanocrystalline transition metal dichalcogenide layers with respect to the substrate. We aim to relate and understand the so-called resistance drift occurring in the endurance test results with our model, which is further tested using density functional theory simulations. We conclude that the relationship between resistance drift and skin effect is dominated by alternating electric current resistance and surface resistance. These results are crucial for understanding the resistance drift occurring in several resistive switching devices operating based on defects and ions.

Ab initio exploration of modified carbon nanotubes as potential corrosion inhibitors

In order to develop novel unexplored potential corrosion inhibitors, covalently modified single-walled carbon nanotubes (SWCNT) via benzoic (–PhCOOH) and aniline (–PhNH2) groups are being investigated as corrosion inhibitors for the first time. Utilizing a comprehensive approach, this study employed density functional theory (DFT), Monte Carlo (MC), and molecular dynamics simulations (MD) to assess the adsorption behavior of modified nanotubes as corrosion inhibitors on the Cu(111) surface within a simulated aqueous HCl corrosion medium. The results provided molecular information on the adsorption capability, geometry adsorption centers, and adsorption energies (Eads) of carbon nanotubes on the surface of Cu(111). The adsorption energy values unveiled robust interactions between SWCNT–PhCOOH and SWCNT–PhNH2 inhibitors and the Cu(111) surface, suggesting a highly effective corrosion protection mechanism. The calculated Eads values exhibited notable ranges, spanning from –260.82 to –308.18 kcal/mol for SWCNT–PhCOOH and –220.92 to –261.01 kcal/mol for SWCNT–PhNH2 with the maximum probability values, representing the most favorable adsorption scenarios, determined to be –292.96 and –229.39 kcal/mol, respectively. A key insight from Monte Carlo simulations underscored the inherent spontaneity of the adsorption process, corroborated by the consistently negative Eads values. These findings collectively underscore the substantial affinity of the inhibitors to the copper surface, contributing to a deeper comprehension of their corrosion inhibition capabilities.

The inhibitor activity of some azo compound derivatives using density functional theory and molecular dynamics simulations

Corrosion poses a significant challenge for metals and alloys, carrying considerable economic and safety consequences. Various manufacturing processes, including surface preparation techniques, further exacerbate it. While corrosion inhibitors are employed to safeguard these materials from corrosion, they can also induce oxidative damage. This study aims to determine the corrosion inhibition efficiency of the specified materials. Density Functional Theory (DFT) and molecular dynamics simulations (MDS) were used to investigate the electronic characteristics of diverse compounds. The study included key parameters including highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap (Eg) between ELUMO and EHOMO, dipole moment, global hardness, softness (σ), ionization energy (I), electron affinity (A), electronegativity (χ), back-donation energy Eb-d, global electrophilicity (ω), electron transfer, global nucleophilicity (ε), and total energy (sum of electronic and zero-point energies). The calculations were executed utilizing the DFT method, employing a 6-311G++(d,p) basis set at the B3LYP level. Our research aimed to rank materials based on their effectiveness in inhibiting corrosion by considering EHOMO, ELUMO, and Eg. The order of effectiveness was found to be as follows: S4 > S3 > S1 > Mad1 > Mad3 > Mad4 > P-azo > Bad4. Additionally, our Investigation delved into alterations in electron affinity (A) and ionization potential (I) within different solvent phases, highlighting their importance in determining the chemical reactivity and stability of the studied compounds. The reactive sites were selected using Fukui indices, and the molecular electrostatic potential (MESP) surface was characterized—a Monte Carlo simulation to further understand these chemicals' adsorption behavior on Fe (110) surfaces. Our findings revealed that these compounds exhibit corrosion inhibition potential due to their high EHOMO, A, σ, ΔN, ΔE-back-donation, and low Eg, ELUMO, I, and η. Moreover, our MESP surface analysis demonstrated their ability to donate electrons to the metal's d-orbitals and receive electrons through back-donation. The compounds investigated in this study exhibit the potential to be employed as corrosion inhibitors in various industrial sectors. As a result, through the use and determination of quantum computational chemistry parameters, the level of corrosion resistance was as follows S3 > S1 > Bad4 > Mad4 > Mad3 > S4 > Mad1 > P-azo.

Antifungal Potential of Secondary Metabolites Derived from Arcangelisia flava (L.) Merr.: An Analysis of In Silico Enzymatic Inhibition and In Vitro Efficacy against Candida Species

Considering the escalating resistance to conventional antifungal medications, it is critical to identify novel compounds that can efficiently counteract this challenge. The purpose of this research was to elucidate the fungicidal properties of secondary metabolites derived from Arcangelisia flava, with a specific focus on their efficacy against Candida species. This study utilized a combination approach comprising laboratory simulations and experiments to discern and evaluate the biologically active constituents present in the dichloromethane extract of A. flava. The in vitro experiments demonstrated that compounds 1 (palmatine) and 2 (fibraurin) exhibited antifungal properties. The compounds exhibited minimum inhibitory concentrations (MICs) ranging from 15.62 to 62.5 µg/mL against Candida sp. Moreover, compound 1 demonstrated a minimum fungicidal concentration (MFC) of 62.5 µg/mL against Candida glabrata and C. krusei. In contrast, compound 2 exhibited an MFC of 125 µg/mL against both Candida species. Based on a molecular docking study, it was shown that compounds 1 and 2 have a binding free energy of −6.6377 and −6.7075 kcal/mol, respectively, which indicates a strong affinity and specificity for fungal enzymatic targets. This study utilized pharmacophore modeling and Density Functional Theory (DFT) simulations to better understand the interaction dynamics and structural properties crucial for antifungal activity. The findings underscore the potential of secondary metabolites derived from A. flava to act as a foundation for creating novel and highly efficient antifungal treatments, specifically targeting fungal diseases resistant to existing treatment methods. Thus, the results regarding these compounds can provide references for the next stage in antifungal drug design. Further investigation is necessary to thoroughly evaluate these natural substances’ clinical feasibility and safety characteristics, which show great potential as antifungal agents.

Terahertz Spectroscopy Unambiguously Determines the Orientation of Guest Water Molecules in a Structurally Elusive Metal-Organic Framework.

Porous materials, particularly metal-organic frameworks (MOFs), hold great promise for advanced applications. MIL-53(Al) is an exceptionally well-studied MOF that exhibits a phase transition upon guest capture─in this case, water─resulting in a dramatic change in the pore volume. Despite extensive studies, the structure of the water-loaded narrow-pore phase, MIL-53(Al)-np, remains controversial, particularly with respect to the positions of the adsorbed water molecules. We use terahertz spectroscopy, coupled with powder X-ray diffraction and density functional theory simulations, to unambiguously resolve this controversy. We show that the low-frequency (<100 cm-1) vibrational spectrum depends on weak long-range forces that are extremely sensitive to the orientation of the adsorbed water molecules. This enables definitively determining the correct structure of MIL-53(Al)-np while highlighting the extreme sensitivity of terahertz spectroscopy to bulk structure, suggesting its potential as a robust complement to X-ray diffraction for precise characterization of host-guest complexes.

Cycloaddition reaction of methylidyne radical with dipyrromethanol: quantum chemical insights into the formation of di(pyridin-2-yl)methanol

Density functional theory was employed to investigate methylidyne radical reaction on to the unsaturation of dipyrromethanol moiety through cycloaddition forming a six membered di(pyridin-2-yl)methanol followed by H-elimination via ring expansion. Time-dependent density functional theory (TD-DFT) simulations were performed to figure out the ultraviolet–visible spectrum of dipyrromethanol and di(pyridin-2-yl)methanol. Ultraviolet–visible spectrum of dipyrromethanol and di(pyridin-2-yl)methanol shows that two sharp absorption peaks were obtained at λ max = 161 nm and 206 nm for the reactant dipyrromethanol while a sharp peak was observed for the product di(pyridin-2-yl)methanol at shorter wavelength (λ max = 170 nm). The theoretical IR spectrum of dipyrromethanol and di(pyridin-2-yl)methanol shows that a significant red shift of 129 cm−1 was observed in the case of di(pyridin-2-yl)methanol due to presence of two strong intra-molecular hydrogen bonds, which indicates its higher stability than the dipyrromethanol. HOMO–LUMO energy gap calculations and natural bond orbital (NBO) analysis endorse the type of electronic transition for the desired product di(pyridin-2-yl)methanol is π–π*. The global reactivity analysis shows the electron donor and acceptor nature of dipyrromethanol and methylidyne radical, respectively. A potential energy surface is constructed via methylidyne radical addition, ring expansion, and hydrogen elimination transition states. Thermodynamics study and potential energy surface of the title reaction indicates its highly exothermicity and spontaneous in nature.

Enhancing Pd Catalytic Activity by Amine Group Modification for Efficient Direct Synthesis of H2O2.

A great deal of research has been carried out on the design of Pd-based catalysts in the direct synthesis of H2O2, mainly for the purpose of improving the H2O2 selectivity by weakening the activation energy on the Pd active site and thus inhibiting the dissociation of the O-O bonds in O2*, OOH*, and HOOH*. However, this often results in insufficient activation energy for the reaction between H2 and O2 on Pd, leading to difficulties in improving both the selectivity and productivity of H2O2 simultaneously. Based on this, this study reports an efficient catalyst composed of amine-functionalized SBA-15-supported Pd. The strong metal-support interaction not only makes the PdNPs highly dispersed with more Pd active sites but also improves the stability of the catalyst. The amine group modification increases the proportion of Pd0, further enhancing Pd activity and promoting the adsorption and conversion of H2 and O2 on Pd, thereby significantly increasing H2O2 productivity. Additionally, the density-functional theory simulation results showed that due to the hydrogen-bonding force between the amine group and H2O2, this particular anchoring effect would make the hydrogenation and decomposition of H2O2 effectively suppressed. Ultimately, both the selectivity and productivity of H2O2 are improved simultaneously.

Epitaxial Metal Electrodeposition Controlled by Graphene Layer Thickness.

Control over material structure and morphology during electrodeposition is necessary for material synthesis and energy applications. One approach to guide crystallite formation is to take advantage of epitaxy on a current collector to facilitate crystallographic control. Single-layer graphene on metal foils can promote "remote epitaxy" during Cu and Zn electrodeposition, resulting in growth of metal that is crystallographically aligned to the substrate beneath graphene. However, the substrate-graphene-deposit interactions that allow for epitaxial electrodeposition are not well understood. Here, we investigate how different graphene layer thicknesses (monolayer, bilayer, trilayer, and graphite) influence the electrodeposition of Zn and Cu. Scanning transmission electron microscopy and electron backscatter diffraction are leveraged to understand metal morphology and structure, demonstrating that remote epitaxy occurs on mono- and bilayer graphene but not trilayer or thicker. Density functional theory (DFT) simulations reveal the spatial electronic interactions through thin graphene that promote remote epitaxy. This work advances our understanding of electrochemical remote epitaxy and provides strategies for improving control over electrodeposition.

Experimental and theoretical insights into Artemisia Stems aqueous extract as a sustainable and eco-friendly corrosion inhibitor for mild steel in 1M HCl environment.

The present research demonstrates an innovative investigation of environmentally friendly mild steel (M-steel) corrosion inhibition using the artemisia stems aqueous extract (ASAEx) as an inhibitor in hydrochloric acid 1M. The standard extraction technique of hydrodistillation was used for producing the aqueous solutions of ASAEx. To assess the ratios of the chemical components, phytochemical screening was used to identify the stems of this plant. We used a variety of methods and techniques in our research on corrosion inhibition, including weight loss measures, surface analysis methods like XPS and SEM/EDS, electrochemical testing like PDP and EIS, as well as computational lead compound evaluation. Maximum inhibitory efficacy was achieved with 400mg/L ASAEx in 1M HCl at 303K, i.e. 90%. The PDP investigation verified the mixed-kind inhibitor status of the ASAEx extract. To describe the surface of M-steel, fitting and synthetic data were used to identify a constant phase element (CPE). SEM surface analysis was also used to detect the ASAEx effect on the surface of M-steel. X-ray photoelectron spectroscopy (XPS) analysis shows the presence of trace molecules of ASAEx on M-steel surface characterizing the bands in Maj-ASAEx (major compound of ASAEx). Density functional theory (DFT) and molecular dynamics simulations (MDs) were used in computational chemistry to clarify the adsorption mechanism and inhibitory impact.

Enhanced Gas Sensing Characteristics of a Polythiophene Gas Sensor Blended with UiO‐66 via Ligand Functionalization

Enhanced Gas Sensing Characteristics of a Polythiophene Gas Sensor Blended with UiO‐66 via Ligand Functionalization

Hierarchical-hollow architecture NiSe2 nanosheets for overall water splitting

Electrolytic water splitting (EWS), regarded as a sustainable and promising strategy for hydrogen production, has received huge attention in recent years. However, the practical application of EWS is greatly hindered by the sluggish kinetics of the oxygen evolution reaction (OER). Herein, we proposed an efficient strategy for the synthesis of hierarchical hollow nickel selenide with significant HER and OER electrocatalytic activity. The as-synthesized NiSe2 possesses low overpotential of ∼85 mV at the current density of 10 mA/cm2 for the HER in 0.5 M H2SO4 and ∼270 mV for OER in 1 M KOH. Importantly, when employed into full water splitting on membrane electrode assembly, it merely requires an ultralow voltage of 1.73 V to achieve the current density of 1 A/cm2, outperforming most of the reported other Ni/Ni-Se based structures. Density Functional Theory (DFT) simulations confirm that the hierarchical hollow NiSe2 structure facilitates the reduction of the Gibbs free energy change of H- and O-containing intermediates in the HER/OER process, which promotes the formation of intermediates and thus accelerates the catalytic kinetics. This work offers an important structure engineering route to develop high catalytic performance materials and sheds light on the promotion of electrocatalytic activity for clean energy utilization.

Hybrid-DFT study of halide perovskites, an energy-efficient material under compressive pressure for piezoelectric applications

Recent studies have reported that lead-halide perovskites are the most efficient energy-harvesting materials. Regardless of their high-output energy and structural stability, lead-based products have risk factors due to their toxicity. Therefore, lead-free perovskites that offer green energy are the expected alternatives. We have taken CsGeX3 (X = Cl, Br, and I) as lead-free halide perovskites despite knowing the low power conversion rate. Herein, we have tried to study the mechanisms of enhancement of energy-harvesting capabilities involving an interplay between structure and electronic properties. A density functional theory simulation of these materials shows a decrease in the band gaps, lattice parameters, and volumes with increasing applied pressure. We report the high piezoelectric responses and high electro-mechanical conversion rates, which are intriguing for generating electricity through mechanical stress.

Molecular Dyad vs Multi‐Component Approach‐Photocatalytic Hydrogen Evolution by Combining Oligothiophene Photosensitizers with [FeFe]‐Hydrogenase Mimics

AbstractA molecular dyad (PS‐CAT) consisting of a metal‐free photosensitiser (PS) and a [FeFe]‐hydrogenase‐inspired [Fe2S2] cluster (CAT) has been synthesized for hydrogen evolution under visible light irradiation. The electrochemical properties of PS‐CAT in the absence and presence of acid were investigated by CV and IR‐SEC. The ground state and excited state photophysical properties of PS and PS‐CAT, and the non‐chemically connected reference system [PS, CAT] were investigated to elucidate the effect of a covalent linkage between PS and CAT on the electronic communication and hence on the catalytic performance. The photo‐relaxation pathway of PS‐CAT was revealed computationally by scalar‐relativistic time‐dependent density functional theory simulations. These studies are complemented by comparative analyses of photocatalytic hydrogen evolution between PS‐CAT and [PS, CAT] under visible light irradiation.

Alkyl chain length affecting the structure and interactions of choline-based amino acid ionic liquids: Insights from a computational study

The influences of the alkyl chain length of amino acid anions on the structure and interactions of choline-based amino acid ([Cho][AA]) ionic liquids were investigated based on density functional theory (DFT) and molecular dynamics (MD) simulations. The most stable configuration of the individual [Cho][AA] ion pair was determined, revealing negligible variations in the binding energy between choline cation ([Cho]+) and different amino acid anions ([AA]−). To further characterize the intermolecular interactions between charged entities, the atoms in molecules theory (AIM) and independent gradient model based on Hirshfeld partition (IGMH) were employed, which highlight the presence of robust hydrogen bonds between [Cho]+ and [AA] −, underscoring their significance in shaping the structure of [Cho][AA] ion pairs. The MD studies exhibited the aggregation of anions in [Cho][AA] ILs, which was attributed to side chain interactions of anions. This aggregation effect becomes more pronounced with the elongation of anionic alkyl chain. Simultaneously, radial distribution functions (RDF) analysis revealed a higher probability of hydrogen bonds occurring between [Cho]+ and [AA]− as the alkyl chain in [AA]− lengthened. Additionally, the hydrogen bond lifetimes roughly display an increasing trend as the alkyl chain of the [AA]− increases, which may be due to the reduced diffusion coefficients of ions. Hopefully, our results would contribute fundamental knowledge regarding the impact of alkyl chain length of anions on the structure and interactions in the choline-based amino acid ionic liquids.

Ab Initio Modeling of Mixed-Dimensional Heterostructures: A Path Forward.

Understanding the electronic structure of mixed-dimensional heterostructures is essential for maximizing their application potential. However, accurately modeling such interfaces is challenging due to the complex interplay between the subsystems. We employ a computational framework integrating first-principles methods, including GW, density functional theory (DFT), and the polarizable continuum model, to elucidate the electronic structure of mixed-dimensional heterojunctions formed by free-base phthalocyanines and monolayer molybdenum disulfide. We assess the impact of dielectric screening across various scenarios, from isolated molecules to organic films on a substrate-supported monolayer. Our findings show that while polarization effects cause significant renormalization of molecular energy levels, band energies and alignments in the most relevant setup can be accurately predicted through DFT simulations of the individual subsystems. Additionally, we analyze orbital hybridization, revealing potential pathways for interfacial charge transfer. This study offers new insights into hybrid inorganic/organic interfaces and provides a practical computational protocol suitable for scaled-up studies.

Understanding the Interface Enhancement Mechanisms of CFRP with the Polydopamine-Polyetheramine Interphase at the Molecular Level.

In this work, polydopamine (PDA) and polyetheramine D230 were selected to construct the PDA-D230 interphase between the carbon fiber (CF) and epoxy matrix. Density functional theory (DFT) and molecular dynamics (MD) simulations were performed to explore the interface enhancement mechanisms of a carbon fiber reinforced polymer (CFRP) with the PDA-D230 interphase from the molecular level. The adsorption characteristics of a PDA molecule on the CF surface were investigated using the DFT method. The results show that stronger π-π stacking interactions are formed due to the structure and orientation preference of the PDA molecule. The interfacial structures and properties of CFRP with the PDA-D230 interphase are derived from MD simulations. The PDA-D230 interphase on the CF surface induces stronger interfacial interaction energy, leading to the better load transfer between the CF and epoxy matrix. The existence of the PDA-D230 interphase on the CF surface can decrease the mean-square displacement (MSD) value and the free volume fraction of CFRP, which restricts the movement of epoxy atoms and inhibits the translational and rotational motion of epoxy chains. Compared with the epoxy using pristine CFs as reinforcement, the interfacial shear stress (ISS) of CFRP with the PDA-D230 interphase is improved by 13.1%. Our results provide valuable insights into the interface characteristics of CFRP with the PDA-D230 interphase, which are of great significance for exploring the strengthening mechanisms for CFRPs with the PDA-D230 interphase.

Exploring curcumin interaction with PLGA nanoparticles via various functional groups: A dispersion-corrected density functional theory and molecular dynamics simulation approach

Density functional theory (DFT)-D3 dispersion corrections and molecular dynamic (MD) techniques were used to research how curcumin (CUR) and poly (lactic-co-glycolic acid) (PLGA) interact in the water phase. Relaxation based on machine learning (ML) algorithms was used to identify the state configuration that was the most stable. The electronic, optical, and infrared (IR) vibrational properties of the studied configurations were then computed. The findings show that since PLGA nanoparticle can transport CUR via chemical interactions, the binding energy of CUR through carbonyl group to PLGA is about −1.092 eV (complex A). The theoretical IR spectrum supports the observation that the functional groups of CUR interacting with PLGA undergo changes, which is consistent with the experimental data. Hence, the Bader charge analysis indicates a charge of about 0.14 (complex A) and 0.17 (complex B) |e| transferred from the PLGA to CUR. The charges in CUR exhibit strong charge transfer to the PLGA structure. The calculated results of the CUR-PLGA complex match the main peak in the 500–580 nm range observed in experiments, and the stable optimal optical absorption diagram aligns with the reported spectra. The total density of states (TDOS) of the studied configurations shows that CUR is having an impact on the HOMO and LUMO levels. The PLGA nanoparticle demonstrates a higher sensitivity (86%) towards the presence of CUR in complex D compared to complex B (67%), which can be attributed to the change in the energy gap. This low adsorption energy and high sensitivity suggest that the PLGA nanoparticle indicates its potential to serve as both a carrier and a sensor for detecting CUR in the water phase.

DFT investigation of M2F superalkali doped dodecafluorophenylene (C13H10F12) derivatives with remarkable static and dynamic NLO response

Herein, based on density functional theory (DFT) simulations, the static and dynamic hyperpolarizabilities of the superalkalides based on Janus molecules have been explored. The designed superalkalides M2F(F)-DDFP-M2F(H) contain Janus based Dodecafluorophenylene (DDFP) molecule doped with superalkalis on both sides acting as both electron acceptors and donors. Thermodynamic stabilities are evident from the negative values of interaction energies, which are observed in the range of −2.96 eV to −3.63 eV. The maximum interaction energy (Eint) obtained is −3.63 eV for Li2F(F)-DDFP-Li2F(H) complex. The NBO (natural bond orbital) and FMO (frontier molecular orbital) analyses confirm the true superalkalide nature of the designed complexes. FMO analysis further reveals the reduction in energy gap E(H-L) from 10.43 eV (for bare DDFP) to 3.17 eV for the designed superalkalis. Furthermore, NLO response of the studied complexes reveals that the maximum values of polarizability (617 au) and hyperpolarizability are seen for Na2F(F)-DDFP-K2F(H) (4.25 × 104 au) complex, which confirms the remarkable NLO response of newly designed superalkalides. Moreover, frequency dependent analysis indicates that the maximum values of simple harmonic generation (SHG), electro-optical pockel effect (EOPE) and hyper Rayleigh scattering are 7.79 × 106, 2.75 × 106 and 4.45 × 106 au, respectively. The EOKE and EFISHG values are 6.79 × 107 and 7.68 × 1010 at 1339 nm suggesting significant increase in the NLO response of the reported complexes. These results manifest that our designed complexes might provide new paths towards the exceptionally high performance NLO materials. Moreover, we expect that the present work will provide guidance for designing and synthesis of superalkali based NLO materials in future.

A combined density functional theory and microkinetics simulations study of electrochemical CO2 reduction on Cu8/SnO2(110): The crucial role of hydrogen coverage

The electrochemical reduction of CO2 (eCO2R) is a promising approach for converting CO2 into valuable chemicals and fuels using renewable energy sources. We investigated the mechanism of eCO2R for a small Cu8 cluster placed on SnO2 containing O vacancies using density functional theory and predicted current density and selectivity by microkinetics simulations within the computational hydrogen electrode model. Low and high H coverages were modeled by Cu8/SnO2-x and Cu8H6/SnO2-x models, using statistical methods to identify their most stable structures. Different CO2 adsorption modes on Cu8/SnO2-x and Cu8H6/SnO2-x surface models, all containing an O vacancy, resulted in distinct reaction pathways, leading to either HCOOH or CO. The preferred formation of HCOOH occurred upon CO2 adsorption on an O vacancy on the Cu8H6/SnO2-x surface, followed by sequential hydrogenation to HCOO and HCOOH. Adsorption of CO2 on Cu8/SnO2-x opened a facile pathway to CO. Electronic structure analysis revealed that differences in charge donation of Cu to the antibonding orbitals of CO2 can explain the predicted selectivity differences. The preferred adsorption mode of CO2 is bidentate at the Cu-SnO2-x interface. Our findings emphasize the role of H coverage on Cu on the selectivity of eCO2R for Cu/SnOx catalysts.