Bifunctional nickel and copper electrocatalysts for CO 2 reduction and the oxygen evolution reaction

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-01, Vol.8 (4), p.1741-1748
• Main Authors: Pan, Hanqing, Barile, Christopher J.
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C9TA12055F

In this study, a bifunctional electrocatalyst for CO 2 reduction and the O 2 evolution reaction (OER) was constructed from the electrodeposition of cuprous oxide (Cu 2 O) and Ni on a carbon substrate. Different Ni thicknesses on Cu 2 O were achieved by varying the time of chronopotentiometric deposition of Ni. Electrochemical CO 2 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. Cu 2 O modified with a Ni overlayer with a thickness of ∼700 nm resulted in the highest formate faradaic efficiency of 18%, and Cu 2 O resulted in highest CO faradaic efficiency of 7.9%. The enhanced faradaic efficiency for formate is attributed to the synergistic effect between Ni and Cu 2 O due to maximized amounts of exposed bimetallic sites that facilitate CO 2 reduction. The electrocatalyst also produces ∼9 times more current density than previous studies using Ni–Cu 2 O electrocatalysts for the OER. The ability of the Ni–Cu 2 O thin films to catalyze both the OER and CO 2 reduction allows them to be incorporated in the first demonstration of a two-electrode CO 2 conversion device with a bifunctional catalyst. In this architecture, the device produces formate and CO with faradaic efficiencies of 16.0% and 19.7%, respectively.