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%) and an outstanding partial current density of -15.5 mA cm-2 in aqueous electrolyte. Furthermore, our investigation delves into the significance of soft acid sites through in situ X-ray adsorption spectroscopy and in situ Raman spectroscopy. The findings from this study offer theoretical insights guiding the design of catalysts for the efficient electrochemical reduction of CO2 to produce CO.

Keywords: E-fuels, CO2 electroreduction, Hard-Soft-Acid-Base, in situ characterization techniques, asymmetric low-frequency pulsed strategy