Full-exposed Cu site of Cu2O-(1 0 0) driven high ethylene selectivity of carbon dioxide reduction

Abstract

Cu2O shows great potential as a catalyst for the electrochemical CO2 reduction reaction (ECO2RR). However, the mechanism behind the formation of different final products from Cu2O nanostructures remains a challenge. In this study, we combine theoretical and experimental approaches to demonstrate that the full-exposed Cu sites in Cu2O (100) microcubes contribute to superior C2H4 selectivity compared to other microstructures such as Cu2O (111), (110), and (311) facets. Density functional theoretical (DFT) calculations reveal that the stronger orbital splitting between Cu 3d and O 2p orbital of Cu2O (100) facet facilitates the formation of neighboring and low valence state Cu active site, thereby enhancing *CO adsorption and C2H4 formation. These DFT results are supported by the synthesis of four kinds of Cu2O microparticles (MPs) with different exposed facets, where cubic-Cu2O with the (100) facet exhibits the highest Faradaic efficiency (61.3 %). This study has significant implications for the structural design and mechanism analysis of innovative catalysts used in ECO2RR.