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

Abstract

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 Cu⁰ 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 Cu⁰ 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 Cu⁰ 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.