Additives‐Modified Electrodeposition for Synthesis of Hydrophobic Cu/Cu₂O with Ag Single Atoms to Drive CO₂ Electroreduction

Abstract Copper‐based electrocatalysts are recognized as crucial catalysts for CO₂ electroreduction into multi‐carbon products. However, achieving copper‐based electrocatalysts with adjustable valences via one‐step facile synthesis remains a challenge. In this study, Cu/Cu₂O heterostructure is constructed by adjusting the anion species of the Cu ions‐containing electrolyte during electrodeposition synthesis. Then, Cu/Cu₂O with tuned nanoarchitectures ranging from dendrites to polyhedrons is achieved by introducing transition metal ions as additives, leading to an adjustable interfacial microenvironment for CO₂/H₂O adsorption on the Cu/Cu₂O electrodes. Additionally, the polyhedral Cu/Cu₂O catalysts are used as templates for depositing Ag single atoms (Ag_SA), which are known as synergistic active sites for promoting ^*CO to ^*COH toward C₂₊ products. The prepared Ag_SA‐Cu/Cu₂O catalyst is evaluated in a flow cell and exhibited a FE_C2+ of 90.2% and a partial current density (jc₂₊) of 426.6 mA cm⁻² for CO₂ electroreduction. As revealed by in situ Raman spectra and density functional theory calculations, the introduction of Ag single atoms slows down the reduction of Cu⁺ during CO₂ electroreduction, especially at a high current density. This work provides a promising paradigm for diverse control of the compositions and hydrophobicity of Cu‐based catalysts for selective CO₂ electroreduction to C₂₊ products.