Mechanistic Understanding of Electrochemical Reactions at Solid-Liquid Interfaces

Electrochemical technology is promising for a clean energy economy. Advancing the mechanistic understanding of electrochemical reactions is essential for developing clean technologies. Using atomic-scale simulations and computational chemistry, interfacial mechanisms at solid-liquid interfaces can be revealed. A deeper understanding of how cations influence surface/interface reactions can guide experimental researchers in engineering electrode-electrolyte interfaces or designing tailored electrolytes to improve performance. Firstly, I will describe our efforts in developing atomic-scale interfacial models to construct the complete free-energy diagram of inner-sphere reactions considering thermodynamic and kinetics at Au-water-cations interfaces. We successfully identify that cations facilitate the inner-sphere reaction kinetics via ab initio molecular dynamics simulations and the slow-growth sampling (AIMD-SG) method.[1][2] Then, examples will be provided, showing how insights can be gained regarding the cation effects on outer-sphere reaction kinetics, via combining the constrained density functional theory molecular dynamics (cDFT-MD) and Marcus theory.[3] Combining these simulation results, we reveal cation effects arise from short-range Coulomb interactions with reaction intermediates, and cations modulate the inner- and outer-sphere pathways. We further show that it is possible to modulate the activity and selectivity of interfacial reactions by tuning the cation identity and concentrations. [4] References: [1] X.P. Qin, T. Vegge, H.A. Hansen*, “CO 2 Activation at Au(110)-Water Interfaces: An Ab Initio Molecular Dynamics Study”, J. Chem. Phys. 2021, 155: 134703. [2] X.P. Qin, T. Vegge, H.A. Hansen*, “Cation-Coordinated Inner-Sphere CO 2 Electroreduction at Au-Water Interfaces”, J. Am. Chem. Soc. 2023, 145: 1897–1905. [3] X.P. Qin*, H.A. Hansen, K. Honkala, M.M. Melander*, “Cation-Induced Changes in the Inner- and Outer-Sphere Mechanisms of Electrocatalytic CO 2 Reduction”, Nat. Commun. 2023, 14: 7607. [4] X.P. Qin*, T. Vegge, H.A. Hansen*, “Modulating Activity and Selectivity of CO 2 Electroreductions at Au-Water Interfaces via Engineering Local Cation Condition”, ACS Catal. 2024, 14: 8168–8175.