Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T59: Electrochemical Interface II Electrochemistry and Catalysis in Aqueous EnvironmentsFocus
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Sponsoring Units: DCOMP Chair: Duy Le, Univeristy of Central Florida Room: Room 301 |
Thursday, March 9, 2023 11:30AM - 12:06PM |
T59.00001: Finite-field DFTMD modelling of protonic double layers and beyond Invited Speaker: Chao Zhang Oxide-electrolyte interfaces are universally present in electrochemistry, electrocatalysis, geochemistry as well as colloid science. The surface charge of all these interfaces is controlled by the pH of the electrolyte solution and this leads to the formation of electric double layers by deprotonation of adsorbed water molecules or protonation of the oxide surfaces [1]. Moreover, the oxide surface can be polarized under electrochemical conditions. Therefore, how to model polarized oxide surfaces with atomistic simulation is an outstanding question. Here, I will first discuss our recent progress on modelling the protonic double layer at metal-oxide/electrolyte interfaces [2-3] using finite-field density-functional theory-based molecular dynamics (DFTMD) simulations [4]. Then, this is followed by our new effort on introducing finite-field coupling in modelling electrified interfaces via machine-learning the charge response kernel with PiNet-chi [5-6]. |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T59.00002: First-Principles Molecular Dynamics Simulations of Indium Oxide/Water Interfaces. Matthew Bousquet, Giulia Galli, Francois Gygi Indium oxide (In2O3) is commonly used as a transparent conducting electrode in photovoltaic and electrochemical cells, due to its high photocatalytic activity, chemical stability, and commercial availability. In particular, indium oxide surfaces in contact with water can produce hydroxyl radicals (•OH) from the splitting of interfacial water molecules, which are required for advanced oxidation processes. In order to optimize desired oxidation processes, it is important to understand the influence of surface hydroxylation, doping (e.g. with tin) and disorder in determining the properties of the interface with water and the ability of the solid oxide to induce water splitting. Here, we carry out first principles molecular dynamics simulations with the SCAN functional and the Qbox code to study indium oxide/water interfaces under different hydroxyl coverages (100%, 98%, 83% and 66% hydroxylation), with the goal of characterizing the structural, electronic, and vibrational properties of the aqueous interface. In particular, computed IR and Raman spectra provide unique insight into hydrogen bonding and dissociation at the interface. Work is in progress to carry out a detailed comparison between simulations and experiments. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T59.00003: Dynamic Level Diagrams: A New Tool for Predicting Isolation of Reaction Intermediates through Joint Density-Functional Theory Colin R Bundschu, Tomas A Arias, Héctor D Abruña, Juan F Mendez-Valderrama, Mahdi Ahmadi The oxygen reduction reaction (ORR) features prominently and is of fundamental importance in the field of electrocatalysis, with direct applications to fuel cells. The alkaline ORR on metal oxide surfaces shows great promise to reduce/eliminate the need for costly platinum group metals (PGMs). Building on the results we presented last year, we present convincing evidence that we have identified the actual reaction pathway on the Co3O4 surface through ab initio calculations, finding excellent agreement with experiment. Using a new tool we have developed, a dynamic interactive energy level diagram, we also demonstrate how 3 out of 4 of the reaction intermediates can be isolated by applying appropriate voltages to the surface for direct confirmation of the pathway via operando experimental tools. Finally, we present results for related spinel materials. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T59.00004: Optimization of VASPsol Solvation Free Energy Predictions Eric C Fonseca, Sean Florez, Richard G Hennig Density functional theory can accurately predict material properties and reaction barriers. However, it is often limited to small system sizes due to high computational costs. In addition, many properties and reaction barriers are dramatically different when solvated. To approximate the solvation effect, computational chemists use continuum models to mimic the countless number of solvent molecules in these systems. Continuum models attempt to capture the effect of the solvent on solute molecules and surfaces while dramatically reducing the computational cost. VASPsol uses a polarizable continuum model within VASP, a plane-wave DFT code. The present work sought to optimize the VASPsol cavity parameters by minimizing solvation energy errors compared to experimentally measured values. The experimental solvation energies are from the Truhlar Minnesota dataset and encompass over 2500 molecules with 80 unique solvents. To minimize the number of evaluations needed to improve VASPsol performance, we used COSMO-SAC sigma-profile descriptors to represent our molecular dataset. We analyzed the resultant errors across chemical groups to optimize VASPsol parameters for multiple solvents. We show that using these optimized parameters, VASPsol can lead to more accurate simulations for the larger community. |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T59.00005: Nuclear quantum effects in the Van Hove Correlation functions of water Rabi Khanal, Stephan Irle Atomistic investigations on the bulk structure of water have shown that the low mass of hydrogen induces substantial nuclear quantum effects (NQE), such as zero-point energy and tunneling, modulating the static pair distribution functions (PDFs), and lowering the energy barrier associated with proton transport. In this study, we have performed path integral molecular dynamics (PIMD) simulations with thermostatted ring polymer MD, using on-the-fly generated energies and forces from the density-functional tight-binding (DFTB) method. We aim to simulate and quantitatively understand NQEs on the dynamic structure of water through analysis of the time-dependent PDF, which is also called the Van Hove correlation function (VHF). The VHF relates molecular behavior and the macroscopic transport properties simultaneously as a function of positions and time. Our study shows that NQEs play a significant role in the correlated water motion, making it essential in the atomistic simulation to predict the correlation characteristics of water with an accuracy comparable to experiment. Remarkably, unlike static PDFs, where O-O PDF experience a negligible NQE compared to O-H and H-H PDFs, all three pairwise VHFs show slower decay of correlations in water dynamics due to NQEs. |
Thursday, March 9, 2023 12:54PM - 1:06PM |
T59.00006: Understanding the Mg aqueous corrosion and the Mg/water interface through first-principles simulation Bingxin Li, Richard Fogarty, Nicholas Harrison, Andrew Horsfield, Chengcheng Xiao Mg, as the lightest metal among engineering metals, has been applied in various industries thanks to its good mechanical property. Nevertheless, further applications of Mg and its alloys are limited by the poor aqueous corrosion resistance of Mg. The very first thing of unravelling the mechanism of Mg aqueous corrosion is to investigate the property of the Mg (0001)/water interface at a molecular level. We use second-generation Car-Parrinello molecular dynamics (MD) to explore the interface structural information, combined with static density functional theory calculations to probe the atomic interactions and the potential of zero charge of the Mg (0001) surface. Several corrosion phenomena of Mg, such as the negative difference effect (NDE), could be attributed to the corrosion product formed during the aqueous corrosion. , which forms underneath the metal surface in a humid environment, could also play an important role in subsequent corrosion reactions. However, the formation mechanism of this hydride is still unclear on an atomistic scale. Therefore, we apply the density functional theory (DFT) to study hydrogen adsorption at different adsorption sites on the clean/hydroxylated/oxidized Mg (0001) surface. The stable structure of the subsurface Mg hydride-like layer is determined, and we demonstrate the connection between the energetically favourable H adsorption with the electron localisation function (ELF) of the surface. To determine the stability of the Mg surface in different adsorption states (with various adsorbates at several coverage), we construct the surface Mg Pourbaix (E-pH) diagram based on a semiconductor-defect-inspired approach. The steadiest surface phase in vacuum/implicit water at different pH and voltage is illustrated in the diagram, which also provides a rational mechanism for explaining the NDE of Mg in the view of thermodynamics. |
Thursday, March 9, 2023 1:06PM - 1:18PM |
T59.00007: Structure and reactivity of bismuth vanadate-water interfaces Giacomo Melani, Wennie Wang, Chenyu Zhou, Mingzhao Liu, Kyoung-Shin Choi, Giulia Galli
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Thursday, March 9, 2023 1:18PM - 1:30PM |
T59.00008: Stabilization of CO2 adsorption on Bi(111) electrode in electrochemical environment using non-metallic cations: A first principles study. Theodoros Panagiotakopoulos, Duy Le, Talat S Rahman
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Thursday, March 9, 2023 1:30PM - 1:42PM |
T59.00009: Copper catalyst surface engineering with CO* adsorbates Henry Yu The electrochemical reduction of CO2 with Cu-based catalysts depends intimately on the instantaneous local chemical environment of the catalyst-electrolyte interface. This microenvironment fluctuates according to the surface concentration of competing reaction intermediates and the applied electrode potential. In practice, disentangling these factors is exceedingly challenging, yet they critically determine catalyst efficiency and selectivity. To address this we use a newly developed grand canonical quantum-classical hybrid method (ESM-RISM), which treats the solvent with atomic accuracy at reasonable computational cost. This method allows us to quantify the complex interdependence between electrode potential, CO∗ coverage, and the interfacial field strength. We show that the oft-overlooked CO∗ coverage effect in fact strongly influences the field strength, with a magnitude change exceeding 1V/Å at certain potentials; among other effects, this change should lower the CO-dimerization barrier that dictates selectivity toward multi-carbon products. Beyond showcasing the importance of surface coverage for CO2R, our results highlight the power of surface additives to modulate interfacial fields toward tailored electrochemical pathways. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T59.00010: End-to-End Modeling of Cyclic Voltammograms for Hydrogen Evolution Reaction from First Principles TIMOTHY T YANG, Wissam A Saidi Hydrogen evolution reaction (HER) is a critical reaction for hydrogen production. In analytical electrochemistry, cyclic voltammetry (CV) has been the practical technique to provide current-potential characteristics based on the Butler-Volmer equation. However, the linkage between the analytical chemistry and first-principles modeling is missing. Herein, we develop an end-to-end electrochemical CV model for HER that is only a function of hydrogen adsorption free energy. At equilibrium conditions, this model reproduces the volcano trend proposed by Nørskov, and significantly improves the discrepancies on exchange currents with experiments owing to a metal-dependent rate-constant. Further, we show that for low-overpotentials, the CV model reproduces experimental cyclic voltammograms with high fidelity. The success of the CV model is justified by the universality of the transfer coefficient and the energy barrier at the equilibrium limit. Our framework for developing the electrochemical model based on fundamental electrochemistry principles and computational quantum-mechanical approaches can be applied to any electrochemical reactions. |
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