Carbon dioxide electroreduction to C2 products over copper-cuprous oxide derived from electrosynthesized copper complex

Efficient electroreduction of carbon dioxide to multicarbon products in aqueous solution is of great importance and challenging. Unfortunately, the low efficiency of the production of C₂ products limits implementation at scale. Here, we report reduction of carbon dioxide to C₂ products (acetic acid and ethanol) over a 3D dendritic copper-cuprous oxide composite fabricated by in situ reduction of an electrodeposited copper complex. In potassium chloride aqueous electrolyte, the applied potential was as low as -0.4 V vs reversible hydrogen electrode, the overpotential is only 0.53 V (for acetic acid) and 0.48 V (for ethanol) with high C₂ Faradaic efficiency of 80% and a current density of 11.5 mA cm⁻². The outstanding performance of the electrode for producing the C₂ products results mainly from near zero contacting resistance between the electrocatalysts and copper substrate, abundant exposed active sites in the 3D dendritic structure and suitable copper(I)/copper(0) ratio of the electrocatalysts.