Restructuring of shape-controlled Cu2O catalysts during CO2 electroreduction

Oxide-derived (OD-Cu) catalysts are well-known catalysts with relatively high activities for the electrochemical reduction of CO 2 (CO 2 RR) to C 2+ products. During CO 2 electrolysis, the strongly reducing conditions lead to a transformation of the morphology and surface sites of copper catalysts. These changes, particularly in the crystallographic orientation of the exposed surfaces, are thought to play an important role in the CO 2 RR performance of the catalysts. Herein, we investigated the relation between the restructuring of as-prepared Cu 2 O catalysts with different shapes and the catalytic performance for the CO 2 RR. The studied electrocatalysts included Cu 2 O cubes and Cu 2 O octahedra, exposing predominantly (100) and (111) facets, respectively. The difference in catalytic performance could be linked to the exposed metallic facets formed during reduction, which is supported by in situ X-ray diffraction (XRD) and cyclic voltammetry. SEM imaging showed that the bulk morphology was maintained accompanied with the formation of small nanoparticles on the surface of the catalysts, likely caused by Cu dissolution and redeposition. The crystallite size of the Cu phase was significantly smaller than that of the Cu 2 O phase, hinting at the substantial restructuring of the catalysts by breaking up of the large particles during the CO 2 RR. • Surface termination of Cu impacts the selectivity for CO 2 electroreduction. • CO 2 electroreduction conditions lead to reconstruction of the catalyst surface. • Nanoparticle formation due to lattice oxygen removal and dissolution/redeposition. • Monitor restructuring of electrocatalysts with in situ characterization methods.