Copper hydroxide/basic copper salt derived Cu⁰ with a clear grain boundary for selective electrocatalytic CO₂ reduction to produce multicarbon products

Electrocatalytic CO2 reduction (ECR) is one of the most promising ways to mitigate CO2 and fuel production, and multicarbon products (C2+) with high chemical value attract lots of interest. Cu is a unique electrocatalyst that can convert CO2 to multicarbon products, but with limited selectivity and activity. Here, aiming for a clear Cu-0 nanoparticle structure with a clear grain boundary, we report a simple and effective method of Cu(OH)(2)/basic copper sulphate compound material synthesis, which is in situ reduced to Cu-0 nanoparticles with a clear grain boundary (GB) during the ECR process. The Cu(OH)(2)/basic copper sulphate-derived Cu nanoparticles show a high C2+ faradaic efficiency (FE) of 81% at -1.2 V vs. RHE, which surpasses that of state-of-the-art Cu-based catalysts evaluated in an H-type cell. Extending the method to other basic copper salts (BCS), we successfully synthesized three other Cu(OH)(2)/BCS species (nitrate, carbonate and chloride), which were also converted to Cu-0 with a clear grain boundary during ECR. DFT calculation results reveal that the GB sites could effectively decrease the energy barrier of the reactant CO2 adsorption and critical C-C coupling steps, which endows the derived Cu electrocatalyst with high selectivity for C2H4 and C2+ products.