(661o) Bifunctional Nickel and Copper Electrocatalysts for CO2 Reduction and the Oxygen Evolution Reaction

In this study, a bifunctional electrocatalyst for CO₂ reduction and the O₂ evolution reaction (OER) was constructed from the electrodeposition of cuprous oxide (Cu₂O) and Ni on a carbon substrate. Different Ni thicknesses on Cu₂O were achieved by varying the time of chronopotentiometric deposition of Ni. Electrochemical CO₂ reduction was carried out at -0.89 V and -1.89 V vs. RHE, and it was found that formate and CO were the two major products. Cu₂O modified with a Ni overlayer with a thickness of ~700 nm resulted in the highest formate Faradaic efficiency of 18%, and Cu₂O resulted in highest CO Faradaic efficiency of 7.9%. The enhanced Faradaic efficiency for formate is attributed to the synergistic effect between Ni and Cu₂O due to maximized amounts of exposed bimetallic sites that facilitate CO₂ reduction. The electrocatalyst also produces ~9 times more current density than previous studies using Ni-Cu₂O electrocatalysts for the OER. The ability of the Ni-Cu₂O thin films to catalyze both the OER and CO₂ reduction allows them to be incorporated in the first demonstration of a two-electrode CO₂ conversion device with a bifunctional catalyst.