Enriching the Local Concentration of CO Intermediates on Cu Cavities for the Electrocatalytic Reduction of CO 2 to C 2+ Products

The electrochemical carbon-dioxide reduction reaction (CO 2 RR) to high-value multi-carbon (C 2+ ) chemicals provides a hopeful approach to store renewable energy and close the carbon cycle. Although copper-based catalysts with a porous architecture are considered potential electrocatalysts for CO 2 reduction to C 2+ chemicals, challenges remain in achieving high selectivity and partial current density simultaneously for practical application. Here, the porous Cu catalysts with a cavity structure by in situ electrochemical-reducing Cu 2 O cavities are developed for high-performance conversion of CO 2 to C 2+ fuels. The as-described catalysts exhibit a high C 2+ Faradaic efficiency and partial current density of 75.6 ± 1.8% and 605 ± 14 mA cm –2, respectively, at a low applied potential (−0.59 V vs RHE) in a microfluidic flow cell. Furthermore, in situ Raman tests and finite element simulation indicated that the cavity structure can enrich the local concentration of CO intermediates, thus promoting the C–C coupling process. More importantly, the C–C coupling should be major through the *CO–*CHO pathway as demonstrated by the electrochemical Raman spectra and density functional theory calculations. This work can provide ideas and insights into designing high-performance electrocatalysts for producing C 2+ compounds and highlight the important effect of in situ characterization for uncovering the reaction mechanism.