Surface charging activated mechanism change: A computational study of O, CO, and CO₂ interactions on Ag electrodes

Electrocatalytic and plasma-activated processes receive increasing attention in catalysis. Density functional theory (DFT) calculations are state-of-the-art tools for the fundamental study of reaction mechanisms and predicting the performance of catalytic materials. Proper application of DFT-based methods is crucial when investigating charge-doped electrode surfaces during electrocatalytic and plasma-activated reactions. Here, as a model electrode for plasma-activated CO2 splitting, we studied the interactions of O, CO, and CO2 with the neutral and progressively charged Ag(111) metal surfaces. We show that the application of correction procedures is necessary to obtain accurate adsorption energy profiles of O atoms, CO and CO2 molecules on Ag surfaces that are under the influence of additional electrons. Interestingly, the oxidation of CO is found to shift from a Langmuir-Hinshelwood mechanism on a neutral electrode to an Eley-Rideal mechanism on charged electrodes. Furthermore, we show that the surface charging of Ag(111) electrodes increase their CO2 reduction performance by enhancing the adsorption of O atoms and desorption of CO molecules. A further increase in the absolute charge-state of the electrode surface is expected to waive the thermodynamic barriers for the CO2 splitting reaction. (C) 2020 The Author(s). Published by Elsevier B.V. and Science Press on behalf of Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences.