Facet Dopant Regulation of Cu ₂ O Boosts Electrocatalytic CO ₂ Reduction to Formate

Abstract Electrochemical carbon dioxide reduction reaction (CO 2 RR) using clean electric energy provides a sustainable route to generate highly‐valuable chemicals and fuels, which is beneficial for realizing the carbon‐neutral cycle. Up to now, achieving a narrow product distribution and highly targeted product selectivity over Cu‐based electrocatalysts is still a big challenge. Herein, sulfur modification on different crystal planes of cuprous oxide (Cu 2 O) is demonstrated, results in an improvement for formate generation to different degrees. Experimental results and density functional theory (DFT) calculations reveal that sulfur species modified on the surface of Cu 2 O (100) facet effectively lower the formation energy of key intermediate *OCOH for formate generation compared with Cu 2 O (111) facet. As a consequence, the modification of p‐Block elements over Cu‐based electrocatalysts is an effective strategy to optimize the adsorption energy of key intermediate during CO 2 RR, leading to a highly selective product.