High‐Rate CO2 Electroreduction to C2+ Products over a Copper‐Copper Iodide Catalyst

Electrochemical CO₂ reduction reaction (CO₂ RR) to multicarbon hydrocarbon and oxygenate (C₂₊ ) products with high energy density and wide availability is of great importance, as it provides a promising way to achieve the renewable energy storage and close the carbon cycle. Herein we design a Cu-CuI composite catalyst with abundant Cu⁰ /Cu⁺ interfaces by physically mixing Cu nanoparticles and CuI powders. The composite catalyst achieves a remarkable C₂₊ partial current density of 591 mA cm^-2 at -1.0 V vs. reversible hydrogen electrode in a flow cell, substantially higher than Cu (329 mA cm^-2 ) and CuI (96 mA cm^-2 ) counterparts. Induced by alkaline electrolyte and applied potential, the Cu-CuI composite catalyst undergoes significant reconstruction under CO₂ RR conditions. The high-rate C₂₊ production over Cu-CuI is ascribed to the presence of residual Cu⁺ and adsorbed iodine species which improve CO adsorption and facilitate C-C coupling.