Three-dimension porous Zn-Cu alloy: An inexpensive electrocatalyst for highly selective CO₂ reduction to CO in non-aqueous electrolyte

Designing cheap and highly active electrochemical CO₂ reduction (ECO₂R) systems are crucial for their commercial applications. Herein, we report a 3D porous Zn-Cu alloy electrode for ECO₂R to CO. A small amount of Cu has a dramatic effect on the micro-morphology of the electrode. Furthermore, DFT calculations confirm that Zn-Cu alloying significantly reduces the formation energy barrier of *CO intermediates. The synergy between the unique 3D porous structure and the alloying effect enables the Cu_0.3Zn_9.7 electrode to achieve up to 90.69 % Faraday efficiency (FE) for CO at −1.2 V (vs. reversible hydrogen electrode (RHE)). Furthermore, we prepare a novel non-aqueous cathode electrolyte consisting of deep eutectic solvent (DES) and propylene carbonate (PC) for ECO₂R. The FE_CO of Cu_0.3Zn_9.7 increased to 94.89 % and the reduction potential decreased to −1 V (vs. RHE). The low cost of preparing 3D porous electrodes and the ease of synthesizing the novel non-aqueous electrolyte render this ECO₂R system for CO promising for large-scale application.