Delocalization state-induced C-O bond weakness for enhancing CO2 electroreduction to CO

Abstract

Manufacturing E-fuels through carbon capture utilization and storage (CCUS), powered by renewable energy conversion, presents a promising pathway towards near-zero emissions for achieving carbon neutrality. However, challenges arise from lower CO selectivity and slower generation rates, leading to suboptimal E-fuels yield and hindering the effective utilization of renewable energy. Drawing inspiration from the hard-soft-based theory, we propose that enhancing the electron delocalization state of catalytic sites can accelerate the CO₂ electroreduction to CO. In line with this hypothesis, we have developed a bimetallic catalyst (Ag-Zn) where Ag nanoclusters loaded on ZnO exhibit highly delocalized electrons. Theoretical calculations indicate that Ag-ZnO significantly expedites the hydroxyl detachment of the adsorbed *COOH intermediate, enhancing the efficiency of CO formation. The Ag-ZnO catalyst demonstrates one of the highest CO₂-electroreduction-to-CO selectivity (97%) in aqueous electrolyte. Furthermore, our investigation delves into the significance of soft acid sites through in situ X-ray adsorption spectroscopy, in situ Raman spectroscopy and asymmetric low-frequency pulsed strategy. The findings from this study offer theoretical insights guiding the design of catalysts for the efficient electrochemical reduction of CO₂ to produce CO.