Which dominates industrial–current–density CO2-to-C2+ electroreduction: Cuδ+ or the microenvironment?

Abstract

The role and reconstitution of the architecture and oxidation state of Cu-based catalysts in the industrial–current–density CO₂ electroreduction (ICD-CO₂R) need to be fully understood. Herein, by utilizing operando/in situ spectroscopy, dendritic copper oxide with ultrahigh C₂₊ Faradaic efficiency in both acidic (77.0% at 0.7 A cm⁻²) and alkaline (82.6% at 0.9 A cm⁻²) media is employed as a prototype to provide scientific insights into the correlation between its dynamic structure and ICD-CO₂R performance. Different from the general understanding, operando X-ray absorption fine structure spectroscopy indicated that active Cu⁺ sites tend to be stable during the ICD-CO₂R both in acidic and alkaline media. Further COMSOL simulation and in situ Raman spectroscopy revealed that the dendritic morphology was found to enhance K⁺ enrichment, increase local pH values, and facilitate the adsorption of *CO intermediates in comparison to copper oxide particles. The comparative studies have confirmed that sharp morphologies play a crucial role in promoting the highly active ICD-CO₂R rather than the oxidation state, of which the updated mechanism derived from these findings will significantly advance the industrialization of CO₂R.