Chemical and Morphological Transformations of a Ag-Cu Nanocatalyst During CO2 Reduction Reaction

Abstract: The conversion of CO2 into high-value chemicals through a photoreduction reaction in water is a promising route to reduce the dependence on fossil fuels. Ag nanoparticles can drive this reaction via localized surface plasmon resonance, but their low selectivity limits usage in industry. Enhancing selectivity toward hydrocarbons or alcohols requires addition of a co-catalyst such as Cu. However, the stabilized surface state created by Ag-Cu interactions is still poorly understood. In this work, soft x-ray Ambient-Pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Grazing-Incidence X-ray Scattering (AP-GIXS) were used to investigate the evolution of Ag-Cu nanoparticles under CO2RR-like conditions. AP-XPS revealed Ag and Cu surface and sub-surface diffusion, while AP-GIXS tracked change of shape and size of nanoparticles induced by diffusion mechanics. Under 532 nm laser irradiation, further oxidation of Cu and Ag sub-surface diffusion were observed, providing invaluable insights into the dynamic restructuring of the catalyst under reaction conditions.