Rapid and Scalable Synthesis of Cuprous Halide-Derived Copper Nano-Architectures for Selective Electrochemical Reduction of Carbon Dioxide

Electrochemical reduction of carbon dioxide (CO₂) into value-added chemicals and fuels provides a promising pathway for environmental and energy sustainability. Copper (Cu) demonstrates a unique ability to catalyze the electrochemical conversion of CO₂ into valuable multicarbon products. However, developing a rapid, scalable and cost-effective method to synthesize efficient and stable Cu catalysts with high selectivity toward multicarbon products at a low overpotential is still hard to achieve and highly desirable. In this work, we present a facile wet chemistry approach to yield well-defined cuprous halide (CuX, X = Cl, Br or I) microcrystals with different degrees of truncations at edges/vertices, which can be ascribed to the oxidative etching mechanism of halide ions. More importantly, the as-obtained cuprous halides can be electrochemically transformed into varied Cu nanoarchitectures, thus exhibiting distinct CO₂ reduction behaviors. The CuI-derived Cu nanofibers composed of self-assembled nanoparticles are reported for the first time, which favor the formation of C₂₊₃ products at a low overpotential with a particular selectivity toward ethane. In comparison, the Cu nanocubes evolved from CuCl are highly selective toward C₁ products. For CuBr-derived Cu nanodendrites, C₁ products are subject to form at a low overpotential, while C₂₊₃ products gradually become dominant with a favorable formation of ethylene when the potential turns more negative. This work explicitly reveals the critical morphology effect of halide-derived Cu nanostructures on the CO₂ product selectivity, and also provides an ideal platform to investigate the structure-property relationship for CO₂ electroreduction.