Theoretical Modeling of Electrochemical Proton-Coupled Electron Transfer

Warburton, Robert E.; Soudackov, Alexander V.; Hammes‐Schiffer, Sharon

doi:10.1021/acs.chemrev.1c00929

Cited by 149 publications

(146 citation statements)

References 422 publications

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“…The proton-coupled electron transfer (PCET) plays a central role in many important chemical and biochemical reactions. , In electrocatalytic HER, the elementary steps formally involve two proton transfers (PT) and two electron transfers (ET). − Stepwise ET-PT or PT-ET process and concerted proton–electron transfer (CPET) process are possible (Figure a). In homogeneous HER (Figure b), the formation of M-H* species is generally considered to be driven via the ET-PT or CPET mechanism. , The heterogeneous HER on an electrode surface is most commonly through the concerted mechanism (Figure c) .…”

Section: Mechanistic Aspectsmentioning

confidence: 99%

Theoretical Advances in Understanding and Designing the Active Sites for Hydrogen Evolution Reaction

2022

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As a fundamental step of water splitting and a stepping stone toward exploring other multielectron transfer processes, the electrocatalytic hydrogen evolution reaction (HER) is an ideal model for both fundamental understanding and electrocatalyst design. Here, we review the fundamentals and recent developments of theoretical insights into HER, covering the mechanistic aspects, key activity descriptors, local environment considerations, and advances beyond the computational hydrogen electrode. Although it is experimentally challenging to explore the active sites and mechanisms in the electrocatalytic process, computational and theoretical advances show great potential in identifying active sites and reaction mechanisms. In this Review, we especially focus in depth on theoretical insights in revealing and designing the active sites for HER. Major challenges ahead will also be discussed at the end of the Review.

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Section: Mechanistic Aspectsmentioning

confidence: 99%

Theoretical Advances in Understanding and Designing the Active Sites for Hydrogen Evolution Reaction

2022

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“…Studies of the ORR mechanism on Fe–N–C materials have benefited from complementary density functional theory (DFT) calculations. − Despite significant computational efforts, modeling redox events at electrified solid–liquid interfaces remains a significant challenge. In molecular electrocatalysis, redox potentials can be computed with high accuracy by combining isodesmic reaction cycles and experimental measurements. − For extended periodic systems, a rigorous treatment of the electrode potential, beyond constant charge DFT, is required to determine constant potential thermodynamics. − Indeed, the Fe(III/II) redox potential in heterogeneous Fe–N–C systems is typically underestimated using constant charge DFT. , In practice, the electrode potential, as well as associated surface charge fluctuations, can be captured using constant potential DFT strategies. ,− Notably, surface charge effects have been shown to be important for describing reactivity at two-dimensional surfaces, such as N-doped graphene, because of the low density of states (DOS) at the Fermi level. , …”

Section: Introductionmentioning

confidence: 99%

Multilevel Computational Studies Reveal the Importance of Axial Ligand for Oxygen Reduction Reaction on Fe–N–C Materials

et al. 2022

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The systematic improvement of Fe–N–C materials for fuel cell applications has proven challenging, due in part to an incomplete atomistic understanding of the oxygen reduction reaction (ORR) under electrochemical conditions. Herein, a multilevel computational approach, which combines ab initio molecular dynamics simulations and constant potential density functional theory calculations, is used to assess proton-coupled electron transfer (PCET) processes and adsorption thermodynamics of key ORR intermediates. These calculations indicate that the potential-limiting step for ORR on Fe–N–C materials is the formation of the FeIII–OOH intermediate. They also show that an active site model with a water molecule axially ligated to the iron center throughout the catalytic cycle produces results that are consistent with the experimental measurements. In particular, reliable prediction of the ORR onset potential and the Fe(III/II) redox potential associated with the conversion of FeIII–OH to FeII and desorbed H2O requires an axial H2O co-adsorbed to the iron center. The observation of a five-coordinate rather than four-coordinate active site has significant implications for the thermodynamics and mechanism of ORR. These findings highlight the importance of solvent–substrate interactions and surface charge effects for understanding the PCET reaction mechanisms and transition-metal redox couples under realistic electrochemical conditions.

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“…where c O , c R , W O , W R , f and ρ(ε) represent the concentration of oxidised species, concentration of reduced species, electron transfer probability for the forward reaction, electron transfer probability for the backward reaction, Fermi distribution function, and the density of electronic states in the electrode. 14,24,25 In a recent study, D. Fraggedakis et al developed the CIET model which treats ions using the classical transition state theory description and electrons using the quantum particle description. 14 CIET then was used to accurately predict the rate of Li ion intercalation into LiFePO 4 as a function of lithium concentration.…”

Section: Theorymentioning

confidence: 99%

Operando characterization and theoretical modelling of metal|electrolyte interphase growth kinetics in solid-state-batteries - Part II: Modelling

Quérel

Seymour

Skinner

et al. 2022

Preprint

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Understanding the interfacial dynamics of batteries is crucial to control degradation and increase electrochemical performance and cycling life. If the chemical potential of a negative electrode material lies outside of the stability window of an electrolyte (either solid or liquid), a decomposition layer (interphase) will form at the interface. To better understand and control degradation at interfaces in batteries, theoretical models describing the rate of formation of these interphases are required. This study focuses on the growth kinetics of the interphase forming between solid electrolytes and metallic negative electrodes in solid-state batteries. More specifically, we demonstrate that the rate of interphase formation and metal plating during charge can be accurately described by adapting the theory of coupled ion-electron transfer (CIET). The model is validated by fitting experimental data presented in the first part of this study. The data was collected operando as a Na metal layer was plated on top of a NaSICON solid electrolyte (Na3.4Zr2Si2.4P0.6O12 or NZSP) inside a XPS chamber. This study highlights the depth of information which can be extracted from this single operando experiment, and is widely applicable to other solid-state electrolyte systems.

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Theoretical Modeling of Electrochemical Proton-Coupled Electron Transfer

Cited by 149 publications

References 422 publications

Theoretical Advances in Understanding and Designing the Active Sites for Hydrogen Evolution Reaction

Theoretical Advances in Understanding and Designing the Active Sites for Hydrogen Evolution Reaction

Multilevel Computational Studies Reveal the Importance of Axial Ligand for Oxygen Reduction Reaction on Fe–N–C Materials

Operando characterization and theoretical modelling of metal|electrolyte interphase growth kinetics in solid-state-batteries - Part II: Modelling

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