Density Functional Theory Simulations Research Articles

Wear-free sliding electrical contacts with ultralow electrical resistivity

Sliding electrical contacts are commonly applied in electrical connectors, such as conductive slip rings, pantographs, switches, and commutators. However, they suffer from several unavoidable problems caused by friction and wear, including high energy consumption, intermittent failures, limited life, and even failure disasters. In this study, we realized an ultralow-friction and long-distance wear-free state, defined as structural superlubricity (SSL), between sliding electrical interfaces under ambient conditions. A conductive SSL can be implemented in experiments with single-crystal graphite flakes on flattened metals, such as Au and Ni films. Furthermore, we found that depositing a 2 to 3-nm-thick diamond-like carbon (DLC) film on a nickel alloy can lead to an even lower resistivity than that of metals alone. In addition, we revealed the mechanism by which DLC films can improve the conductivity between graphite and metals through density functional-theory simulations. In addition, we prepared a prototype of the SSL slip ring and proved that it possessed ultralow friction, was wear-free, and had no intermittent failures. Consequently, our results demonstrate a unique type of electrical-contact interface for applications requiring conduction while sliding. Thus, we opened the door for SSL electromechanical coupling.

Enhanced corrosion protection of copper in saline environments using bio-nanocomposite coatings based on chitosan and chitosan Schiff base

An in-depth study focuses on developing new environmentally friendly bio-nanocomposites, by incorporating SrTiO3 (STO) ceramic nanoparticles into matrices of chitosan and its derivatives, aiming to use them as protective coatings against corrosion. The various stages of this study include the cross-linking of chitosan, the synthesis of Schiff base chitosan, the cross-linking of Schiff base chitosan, and the preparation of nanocomposite coatings. The coatings' structure and composition were analyzed using different methods, including Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance (FTIR-ATR), X-ray Diffraction (XRD), Transmission Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (TEM-EDX), and Scanning Electron Microscopy (SEM). In addition, Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) measurements were carried out to assess the inhibitory efficacy of chitosan crosslinked with epichlorohydrin (Cs-Ep), epichlorohydrin-crosslinked chitosan-salicylaldehyde Schiff base (CS-S-Ep) and CS-Ep-STO and CS-S-Ep-STO nanocomposite coatings, as well as the long-term protection durability of CS-S-Ep-STO. These techniques revealed a significant reduction in corrosion current density after chemical modification of chitosan and incorporation of SrTiO3 (STO) nanoparticles into CS-Ep and CS-S-Ep matrices, confirming a notable improvement in the inhibitory efficiency of these coatings against copper corrosion in a saline environment. Computational modeling methods like Density Functional Theory (DFT), Molecular Dynamics (MD), and Monte Carlo (MC) simulations reinforced these results by demonstrating efficient adsorption of CS-S-Ep-STO nanocomposites on metal surfaces through the interaction with heteroatoms present in the functional groups (-C=N-, -C-O-, -OH) and STO nanoparticles. The present study's findings provide key information for developing innovative protective coatings, highlighting the potential of chitosan-based nanocomposites and derivatives, particularly with SrTiO3 incorporation, in mitigating metal surface corrosion in aggressive environments.

Regulated Charge Transfer in Donor‐Acceptor Metal‐Organic Frameworks for Highly‐Sensitive Photodetectors

In photo‐induced charge separation, organic thin films with donor and acceptor chromophores are vital for uses such as artificial photosynthesis and photodetection. The main challenges include optimizing charge separation efficiency and identifying the ideal acceptor/donor ratio. Achieving this is difficult due to the variability in molecular configurations within these typically amorphous organic aggregates. Metal‐organic frameworks (MOFs) provide a structured solution by enabling systematic design of donor/acceptor blends with adjustable ratios within a crystalline lattice. We demonstrate this approach by incorporating donor and acceptor naphthalenediimide (NDI) chromophores as linkers in a highly oriented, monolithic MOF thin film. By adjusting the NDI acceptor linker concentration during the layer‐by‐layer assembly of surface‐anchored MOF thin films (SURMOFs), we significantly enhanced charge separation efficiency. Surprisingly, the optimum acceptor concentration was only 3%, achieving a forty‐fold increase in photodetection efficiency compared to baseline NDI donor‐based SURMOFs. This unexpected behaviour was clarified through theoretical analysis enabled by the well‐defined crystalline structure of the SURMOFs. Using density functional theory and kinetic Monte Carlo simulations, we identified two opposing effects from acceptors: the positive effect of suppressing undesirable charge carrier recombination is offset at high concentrations by a reduction in charge‐carrier mobility.

Regulated Charge Transfer in Donor‐Acceptor Metal‐Organic Frameworks for Highly‐Sensitive Photodetectors

In photo‐induced charge separation, organic thin films with donor and acceptor chromophores are vital for uses such as artificial photosynthesis and photodetection. The main challenges include optimizing charge separation efficiency and identifying the ideal acceptor/donor ratio. Achieving this is difficult due to the variability in molecular configurations within these typically amorphous organic aggregates. Metal‐organic frameworks (MOFs) provide a structured solution by enabling systematic design of donor/acceptor blends with adjustable ratios within a crystalline lattice. We demonstrate this approach by incorporating donor and acceptor naphthalenediimide (NDI) chromophores as linkers in a highly oriented, monolithic MOF thin film. By adjusting the NDI acceptor linker concentration during the layer‐by‐layer assembly of surface‐anchored MOF thin films (SURMOFs), we significantly enhanced charge separation efficiency. Surprisingly, the optimum acceptor concentration was only 3%, achieving a forty‐fold increase in photodetection efficiency compared to baseline NDI donor‐based SURMOFs. This unexpected behaviour was clarified through theoretical analysis enabled by the well‐defined crystalline structure of the SURMOFs. Using density functional theory and kinetic Monte Carlo simulations, we identified two opposing effects from acceptors: the positive effect of suppressing undesirable charge carrier recombination is offset at high concentrations by a reduction in charge‐carrier mobility.

Rational design of MoS2/CNT heterostructure with rich S-vacancy for enhanced HER performance

Molybdenum disulfide (MoS2) is a promising electrocatalyst for the hydrogen evolution reaction (HER) due to excellent stability and low cost. However, the utilization in electrocatalytic hydrogen evolution is constrained by inherent shortcomings, including fewer edge active sites, poor dispersion, and electrical conductivity. In this work, MoS2 was compounded with carbon nanotubes (CNTs), which are known for their high specific surface area and excellent electrical conductivity. These CNTs, laden with oxygen-containing functional groups, provided nucleation sites that facilitated the rapid assembly of MoS2 nanoflowers under hydrothermal conditions within 3 h. Due to their diminutive size (∼300 nm), these nanoflowers possess a large specific surface area and numerous active sites at their edges. Furthermore, MoS2 nanoflowers exhibited a high concentration of intrinsic S-vacancies. This heterojunction material exhibited superior HER properties. In addition, density functional theory simulation further confirmed that the MoS2 with S vacancy and CNT heterojunction electrocatalysts (VS-M/C) provided a fast charge transfer pathway for water electrolysis, and analysis showed that the conduction band minimum and valence band maximum were mainly contributed by the d orbits of Mo and the p orbits of C. This study proffered a novel approach for the engineering of high-performance MoS2-based HER electrocatalysts.

Hot carrier transfer from plasmon decay in Ag20at H-Si(111) surface: real-time TDDFT simulation in Wannier gauge.

Plasmon decay is believed to play an essential role in inducing hot carrier transfer at the interfaces between plasmonic nanoparticles and semiconductor surfaces. In this work, we employ real-time time-dependent density functional theory (RT-TDDFT) simulation in the Wannier gauge to gain quantum-mechanical insights into the nonlinear dynamics of the plasmon decay in the Ag20nanoparticle at a semiconductor surface. The first-principles simulations show that the plasmon decay is more than two times faster when the Ag20nanoparticle is adsorbed on a hydrogen-terminated Si(111) surface, taking place within 100 femtoseconds of the plasmon excitation. Hot carrier transfer across the interface is observed as the plasmon decay takes place, and nearly 30% of holes are generated deep in the valence band of the semiconductor surface. The use of Wannier gauge in RT-TDDFT simulation is particularly convenient for gaining quantum-mechanical insights into non-equilibrium electron dynamics in complex heterogeneous systems.

Modeling martensitic transformation temperatures in Zirconia–Ceria solid solutions using machine learning interatomic potentials

Abstract Shape memory ceramics (SMCs), while exhibiting high strength, sizeable recoverable strain, and substantial energy damping, tend to shatter under load and have low reversibility. Recent developments in SMCs have shown significant promise in enhancing the reversibility of the shape memory phase transformation by tuning the lattice parameters and transformation temperatures through alloying. While first-principles methods, such as density functional theory (DFT), can predict the lattice parameters and enthalpy at zero Kelvin, calculating the transformation temperature from free energy at high temperatures is impractical. Empirical potentials can calculate transformation temperatures efficiently for large system sizes but lack compositional transferability. In this work, we develop a model to predict transformation temperatures and lattice parameters for the Zirconia–Ceria solid solutions. We construct a machine learning inter-atomic potential (MLIAP) using an initial dataset of DFT simulations, which is then iteratively expanded using active learning. We utilize reversible scaling to compute the free energy as a function of composition and temperature, from which the transformation temperatures are determined. These transformation temperatures match experimental trends and accurately predict the phase boundary. Finally, we compare other relevant design parameters (e.g. transformation volume change) to demonstrate the applicability of MLIAPs in designing SMCs.

Highly Selective On‐Surface Dehydrogenative Aromatization of n‐Hexyl to Phenyl Substituents

Dehydrogenative aromatization of alkyl substituents represents a powerful approach to aryl‐substituted functional molecules. However, the inertness of alkyl groups and the need for harsh reaction conditions accompanied by low product selectivity hamper its widespread applications. Here, we demonstrate the highly selective on‐surface thermal aromatization of n‐hexyl substituents on polycyclic aromatic hydrocarbons (PAHs) to their phenyl‐substituted analogues under mild conditions. After depositing two representative precursor molecules, n‐hexyl‐substituted hexaphenylbenzene (HPB‐Hex) and bianthryl octacarboxylic tetraimide (BATI‐Hex), onto a pre‐heated Au(111) substrate, dehydroaromatization of the peripheral n‐hexyl groups into phenyl rings occurs, following the planarization of hexaphenylbenzene and bianthryl core. This process involves sequential intramolecular C‐C bond rotations, dehydrogenation, and cyclodehydrogenation reactions, yielding phenyl‐substituted hexabenzocoronene (HBC‐Ph) and bisanthene octacarboxylic tetraimides (BSTI‐Ph). The reaction sequences were monitored using scanning tunneling microscopy (STM) and bond‐resolved non‐contact atomic force microscopy (nc‐AFM), offering structural proof of both intermediates and final products. These experimental techniques were complemented by density functional theory (DFT) simulations, which facilitated the detection of crucial steps in the conversion of n‐hexyl to phenyl groups. Moreover, the effect of alkyl aromatization on the electronic properties of the newly formed aromatic hydrocarbons was elucidated using scanning tunneling spectroscopy (STS).

Highly Selective On‐Surface Dehydrogenative Aromatization of n‐Hexyl to Phenyl Substituents

Dehydrogenative aromatization of alkyl substituents represents a powerful approach to aryl‐substituted functional molecules. However, the inertness of alkyl groups and the need for harsh reaction conditions accompanied by low product selectivity hamper its widespread applications. Here, we demonstrate the highly selective on‐surface thermal aromatization of n‐hexyl substituents on polycyclic aromatic hydrocarbons (PAHs) to their phenyl‐substituted analogues under mild conditions. After depositing two representative precursor molecules, n‐hexyl‐substituted hexaphenylbenzene (HPB‐Hex) and bianthryl octacarboxylic tetraimide (BATI‐Hex), onto a pre‐heated Au(111) substrate, dehydroaromatization of the peripheral n‐hexyl groups into phenyl rings occurs, following the planarization of hexaphenylbenzene and bianthryl core. This process involves sequential intramolecular C‐C bond rotations, dehydrogenation, and cyclodehydrogenation reactions, yielding phenyl‐substituted hexabenzocoronene (HBC‐Ph) and bisanthene octacarboxylic tetraimides (BSTI‐Ph). The reaction sequences were monitored using scanning tunneling microscopy (STM) and bond‐resolved non‐contact atomic force microscopy (nc‐AFM), offering structural proof of both intermediates and final products. These experimental techniques were complemented by density functional theory (DFT) simulations, which facilitated the detection of crucial steps in the conversion of n‐hexyl to phenyl groups. Moreover, the effect of alkyl aromatization on the electronic properties of the newly formed aromatic hydrocarbons was elucidated using scanning tunneling spectroscopy (STS).

Mechanism insights and experimental feasibility of using boron nitride nanocones for rapid adsorption and degradation of SF6 decomposition compounds

Gas-insulated switchgear (GIS) employs sulfur hexafluoride (SF6) as an insulating medium to shield electrical gadget. However, SF6 can decompose under sure situations, generating dangerous sulfur-based totally compounds which include SO2, SOF2, and SO2F2. These byproducts pose enormous dangers to both protection and environmental integrity. Efficiently adsorbing and disposing of those compounds is critical for ensuring operational reliability and reducing environmental dangers. This study investigates the adsorption and degradation mechanisms of SF₆ decomposition compounds (SO₂, SOF₂, and SO₂F₂) on boron nitride nanocones (BNNCs) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Our comprehensive analysis covers five distinct systems, exploring individual and combined adsorption scenarios. The findings reveal that the apex of BNNCs plays a crucial role in the adsorption process, showing high efficiency in adsorbing SO₂ (adsorption energy − 1.22 eV) and facilitating the catalytic breakdown of SOF₂ (adsorption energy − 1.57 eV). The positively charged potential at the nanocone’s apex significantly influences the dissociation and subsequent adsorption of fluorine atoms, with an energy barrier for F dissociation at the apex (1.8 kcal/mol) much lower than at the sidewall (5.3 kcal/mol). In gas mixtures, SO₂ preferentially binds to the apex region of BNNCs, with a bond length of approximately 1.38 Å. BNNCs demonstrate superior adsorption capabilities for SO₂ and SOF₂ compared to other boron nitride nanostructures, with adsorption energies up to 89% higher. The electron transfer analysis reveals that BNNC complexes act as potent electron donors, particularly in the case of BNNC@3SO₂F₂. Additionally, BNNCs show significant potential as sensors for detecting SO₂F₂, with a rapid recovery time of 4.67 ps and a notable decrease in the Fermi level energy to -4.97 eV upon adsorption. The study also provides insights into the angular distribution and charge density difference profiles, offering a detailed understanding of the adsorption mechanisms. These findings have important implications for improving the safety and efficiency of gas-insulated switchgear (GIS) and contribute to the development of more effective environmental protection solutions in electrical power systems.

Efficient UV-Vis-NIR Responsive CO2 Reduction Photocatalyst with Black Pinecone-Shaped Carbon Nitride Loaded with Lanthanum Oxide.

Photothermal catalysis combines the advantages of photocatalysis and thermal activation, which provides a new research angle for CO2 catalytic reduction. In this study, Black carbon nitride with a three-dimensional (3D) pinecone-shaped structure (BPCN) was prepared by a simple solvothermal method using melamine as a precursor without the aid of a template. Lanthanum oxide doping on the BPCN catalysts (BPCN-La) was achieved by ultrasonic impregnation. This unique pinecone-shaped structure consists of self-assembled and interlaced carbon nitride rods (by SEM). The lanthanum element was distributed on the surface of the CN framework in the form of La2O3 (by XPS). The chemical structures of the samples were characterized by solid-state 13C nuclear magnetic resonance (13C NMR) and elaborated by density functional theory (DFT) analysis. This black carbon nitride expanded the light absorption band edge into the near-infrared (NIR) (300-1400 nm, by UV-vis absorption spectra) and had excellent photothermal conversion activity. La atom doping can significantly boost photogenerated electron excitation (by photocurrent test) and promote carrier separation and transfer (by PL). Upon incorporation of La atoms into BPCN, the highest occupied molecular orbital (HOMO) orbital is more concentrated on the oxygen atoms of La2O3. BPCN-La considerably narrowed the band gap width, exhibited an exceptional photothermal effect, and provided a large surface area, which significantly enhanced the photocatalytic reduction of CO2 reactions. The yields of CO reached 58.2 and 104.9 μmol·h-1·g-1 for BPCN and BPCN-La, respectively, with GCN as the control (6.3 μmol·h-1·g-1). Theoretical reaction pathways and selectivity for the photoreduction of CO2 on BPCN and BPCN-La were studied by DFT simulation. This work provides a new vision for the design of photothermal synergistic without extra-thermal input and full spectral response photocatalysts with high efficiency.

Tailoring ORR Activity in Fe-N-C Catalysts through Phosphorus Incorporation.

Atomically dispersed iron and nitrogen co-doped carbon materials (Fe-N-C) represent promising non-precious metal catalysts for the oxygen reduction reaction (ORR), offering potential alternatives to noble metal-based benchmarks. In our study, we investigated the influence of phosphorus doping on the catalytic activity of Fe-N-C. The experimental research demonstrate that the doping of phosphorus significantly enhances the ORR activity. Specifically, the resulting Fe-NPC exhibits high metal loading and excellent ORR activity in 0.1 M KOH with an onset potential of 1.00 V and a half-wave potential of 0.864 V. Density functional theory (DFT) simulations reveal that phosphorus improves the electrocatalytic activity by activating O2 molecules and reducing the energy barrier (the hydrogenation reaction *OH→H2O) of the rate-determining step. Furthermore, Fe-NPC exhibits promising application prospects as an air cathode in Zn-air batteries, delivering a high maximum discharge power density of 180.3 mW cm-2 and outstanding discharge specific capacity (758.8 mAh g-1Zn) at a discharge current density of 10 mA cm-2.

Ultrafast complete dechlorination enabled by ferrous oxide/graphene oxide catalytic membranes via nanoconfinement advanced reduction

Chlorinated organic pollutants widely exist in aquatic environments and threaten human health. Catalytic approaches are proposed for their elimination, but sluggish degradation, incomplete dechlorination, and catalyst recovery remain extremely challenging. Here we show efficient dechlorination using ferrous oxide/graphene oxide catalytic membranes with strong nanoconfinement effects. Catalytic membranes are constructed by graphene oxide nanosheets with integrated ultrafine and monodisperse sub-5 nm nanoparticles through simple in-situ growth and filtration assembly. Density function theory simulation reveals that nanoconfinement effects remarkably reduce energy barriers of rate-limiting steps for iron (III)-sulfite complex dissociation to sulfite radicals and dichloroacetic acid degradation to monochloroacetic acid. Combining with nanoconfinement effects of enhancing reactants accessibility to catalysts and increasing catalyst-to-reactant ratios, the membrane achieves ultrafast and complete dechlorination of 180 µg L−1 dichloroacetic acid to chloride, with nearly 100% reduction efficiency within a record-breaking 3.9 ms, accompanied by six to seven orders of magnitude greater first-order rate constant of 51,000 min−1 than current catalysis. Meanwhile, the membranes exhibit quadrupled permeance of 48.6 L m−2 h−1 bar−1 as GO ones, because nanoparticles adjust membrane structure, chemical composition, and interlayer space. Moreover, the membranes show excellent stability over 20 cycles and universality for chlorinated organic pollutants at environmental concentrations.

Concentrated C2+ Alcohol Production Enabled by Post-Intermediate Modulation and Augmented CO Adsorption in CO Electrolysis.

The electrocatalytic synthesis of multicarbon products from CO2/CO feedstock represents a sustainable method for chemical production with a reduced carbon footprint. Traditional copper catalysts predominantly produce alkenes, but generating valuable and versatile C2+ alcohols, especially high-energy-density C3 alcohols, has been challenging due to issues with selectivity, activity, and stability. Here, we present the construction of Ru-doped Cu nanowires that enhance the selectivity of n-PrOH and C2+ alcohols. In situ Raman spectroscopy shows that our approach promotes both *CO binding and availability, particularly facilitating the formation of high-frequency-bound *CO (*COHFB) and maintaining multiple *CO adsorption modes on Ru-modified and bare low-coordinated Cu nanowires. Density-functional theory (DFT) simulations illustrate that introducing Ru species onto a low-coordinated Cu step surface simultaneously stabilizes CO and alcohol-related intermediates, shifting the dominant reaction pathway toward alcohols and facilitating CO-C2 coupling at the expense of ethylene selectivity. In an alkaline gas-diffusion electrolyzer, we attained a maximum Faradaic efficiency (FE) of 35.9% for n-PrOH and 62.4% for the total C2+ alcohols. Optimizing parameters in the membrane electrode assembly (MEA) system enabled the one-pot generation and separation of C2+ alcohols, achieving a record concentration of 18.8 wt % (4.2 wt % n-PrOH and 14.6 wt % EtOH) with nearly 100% purity at 200 mA/cm2 over 100 h. This work not only provides new insights and guidance for the development of future catalysts from the perspectives of surface science and mechanisms but also highlights the importance of coupling material engineering with reactor engineering to optimize the production process of high-value alcohol products.

Molecular Mechanism of Physical and Mechanical Improvement in Graphene/Graphene Oxide-Epoxy Composite Materials.

The performance provided by graphene (Gr) and graphene oxide (GO) additives can be improved by achieving strong adhesion and uniform dispersion in the epoxy resin matrix. In this study, molecular modeling and simulation of DGEBA/DETA based epoxy nanocomposites containing Gr and GO additives were performed. Density functional theory and molecular dynamics simulations were used to investigate interfacial interaction energies and Young's Modulus. Improvement in the interaction energies was studied by controlling the epoxy:hardener ratio, type and the number of oxygen-containing functional groups on the GO, the mass percentage of Gr/GO filler in the epoxy matrix, size and dispersion of GO in the cell. It was demonstrated that functional groups with up to 10 % oxygen content in GO significantly increase interfacial interaction energy for large size Gr/GO. Increasing DETA type amine ratio in the preparation of epoxy polymers increases the interaction energy for high oxygen content while decreasing the interaction energy for low oxygen content in GO for small size GO with edge functional groups. The performance of material dramatically decreased even at high DETA hardener and high GO mass percentages when the aggregation factor of Gr/GO was included in simulations that explain lower Gr/GO percentages in the experimental studies.

2D heterostructures of graphene oxide and MoS2 to improve sensitivity performance of flexible pressure sensor with shell biological structure

Inspired by the multilayer structure of the shellfish, a novel two-dimensional (2D) composite structure consisting of graphene oxide, MoS2 and graphene oxide (G/M/G) was integrated to the flexible pressure sensing. The composite structure was prepared by the vacuum suction filtration in order to imitate the high toughness of shellfish. Based on the strategy of strain engineering, a comprehensive experimental bench capable of meeting different strain conditions was connected to a push–pull meter and an LCR digital bridge, and then a computer was used to record the changes in transducer capacitance when an external load was applied to the meter. Graphene oxide (GO) and G/M/G supercells were constructed, and density functional theory (DFT) simulations of the initial energy band structure under strain-free conditions were carried out to determine the relationship between the band gap, conductivity, capacitance, and sensitivity of the G/M/G structure based on band gap theory, and to easily understand the mechanism of the shellfish heterostructure leading to enhanced sensitivity of the sensors. Using two-point bending and axial tensile tests, a flexible pressure sensing device was designed to realize positive strains in the ranges of 0%–5 % and 5%–50 %. The results show that the sensitivity of both GO and G/M/G capacitive pressure sensors decreased with increased strain, and the sensitivity of the G/M/G sensors was significantly improved by 75%–102 % compared to the GO sensors at the same strain. The parallel-plate capacitor model and crack growth theory well explain the experimental results at small and large strains. Our results provide new concepts for the design of novel flexible sonar with high sensitivity and large strain operating range by a simple vacuum filtration method, which can be extended to the design of other high-performance 2D flexible electronic devices.

First‐Principles Molecular Dynamics Study on Reductive Stability of High Concentration Electrolyte on Zn Doped Cu Current Collector Surface

AbstractIn enhancing the lifespan of anode‐free Li metal batteries (AFLMBs), current collector (CC) engineering is crucial for achieving uniform and dendrite‐free lithium deposition. The commonly used copper (Cu) CC is unsatisfactory because of its poor lithiophilicity. Here, we consider Zn doping on the Cu CC surface (Zn−Cu) and explore the reductive stability of a high‐concentration electrolyte (HCE), consisting of 3.6 M Lithium Hexafluorophosphate (LiPF6) salt in a mixture of ethylene carbonate (EC) and diethylcarbonate (DEC), on the Zn−Cu (111) surface (HCE|Zn−Cu) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. The interfacial reactions in the HCE|Zn−Cu system are compared to those on the pristine Cu (111) surface (HCE|Cu). We have also studied the effect of electron‐rich environments on the decomposition mechanism of the HCE mixture on both the CC surfaces. It is found that the HCE mixture is electrochemically stable on both Cu and Zn−Cu surfaces in a neutral environment. However, under electron‐rich conditions, only one DEC molecule has decomposed upon contact with the Cu CC surface, while the two PF6− anion groups from Li salts have decomposed much faster (within 100 fs) when the HCE mixture interacts with the Zn−Cu surface. Our results indicate that Zn doping suppresses undesirable solvent decomposition and improves the quality of the solid electrolyte interphase (SEI) layer.

Exploring Chlorinated Solvents as Electrolytes for Lithium Metal Batteries: A DFT and MD Study

ABSTRACTElectrolytes with fluorinated solvents have been regarded as a promising strategy to stabilize high‐voltage cathodes and the interphase of lithium anode in lithium metal batteries (LMBs). However, the rigorous synthesis approach and high cost have led to a demand for developing cost‐effective solvents with suitable properties for LMBs. Herein, we explored the possibility of using chlorinate solvents as electrolytes using density functional theory (DFT) and classical molecular dynamics (MD) simulation. Taking ether (1,2‐dimethoxyethane [DME], 1,3‐dioxolane [DOL]), carbonate (dimethyl carbonate [DMC], and ethylene carbonate [EC]) as examples, we first compared the energy variation of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) upon Cl and F substitution. In particular, we found that 1,2‐bis(chloromethoxy)ethane (DME‐2Cl‐2) has the lowest HOMO and the highest LUMO level among the chlorinated DME after coordinating with Li+, enabling a potentially wide voltage stability. Further MD simulation reveals that lithium ions in DME‐2Cl‐2 has a weaker solvation coordination with solvents but stronger interaction with anions than DME and 1,2‐bis(Fluoromethoxy)ethane (DME‐2F‐2), which is more beneficial for forming stable anion‐derived solid electrolyte interphase (SEI). Our findings suggest that chlorinated solvents can be used as promising electrolytes for LMBs.

Exploring the potent corrosion inhibition properties of phenolic Schiff bases on mild steel in acidic environments, part A: coupling experimental and theoretical investigations.

In this study, we conduct a comparative investigation into the corrosion inhibition properties of two Schiff base compounds, namely 4,4'-((1E,1'E)-(ethane-1,2 diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB5) and (1E,1'E)-N,N'-(ethane-1,2 diyl)bis(1-(4-nitrophenyl)methanimine) (PSB6), on mild steel in an acidic environment. The inhibitory efficiency and adsorption behavior of the inhibitors were assessed through electrochemical and gravimetric analyses. The inhibitors' deposition was further verified by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The findings of electrochemical tests demonstrate that these chemical compounds are potent inhibitors, with 96.5% inhibition provided by PSB5 at 10-3M. Therefore, PSB5 and PSB6 inhibitors are likely of mixed-form, as evidenced by changes in their Ecorr values of 59.8 mV and 33.0 mV, respectively when compared to the blank solution. Furthermore, the adsorption of these inhibitors onto the MS surface, as determined by the Langmuir adsorption isotherm, yielded free energy values of - 38.40 kJ mol-1 for PSB5 and - 35.20 kJ mol-1 for PSB6. These findings highlight a robust and spontaneous adsorption process for both inhibitors. Surface analysis using SEM-EDS revealed the preservation of the mild steel surface morphology and the adsorption of inhibitors. Theoretical investigations utilizing density functional theory (DFT) and molecular dynamics (MD) simulations supported and complemented the experimental findings. This research enhances the understanding of the corrosion protection potential of Schiff base compounds and their potential applications in various industries.

Electronic Structure Engineering of RuNi Alloys Decrypts Hydrogen and Hydroxyl Active Site Separation and Enhancement for Efficient Alkaline Hydrogen Evolution.

Rational design of the active sites of hydrolysis dissociation intermediates to weaken their active site competition and toxicity is a key challenge to achieve efficient and stable hydrogen evolution reaction (HER) in ruthenium-containing alloys. Density Functional Theory (DFT) simulations reveal that the transfer of the d-band electrons from Ru to Ni in RuNi alloys results in a Gibbs free energy of -0.12eV for the Ru0.250Ni Fcc-site H*. In addition, the high spin state of the electrons outside the Ru nucleus strengthens the adsorption of OH* on the Ru─Ni bond, which weakens the active-site competition and toxicity successfully. This theoretical prediction is confirmed by electrodeposition of prepared aRuxNi, and the RuNi alloys obtained by Ru atom doping have excellent HER properties. aRu0.250Ni has overpotentials of 38 and 162.4mV at -10 and -100mAcm-2, respectively, and can be stably operated at -100mAcm-2 Dual-electrode system aRu0.250Ni//bRu0Ni demonstrates an ultra-low battery voltage (1.86V @500mAcm-2) and excellent stability (24h@300mAcm-2). This holistic work resolves the mechanism of active site separation and strengthening in RuNi alloys, and provides a new design idea for the preparation of highly efficient alkaline HER electrodes.