Cuprous Oxide Electrodeposited with Nickel for the Oxygen Evolution Reaction in 1 M NaOH

The electrolysis of water is limited by the high overpotential of the oxygen evolution reaction (OER). In search of an inexpensive and efficient catalyst for OER, we construct electrocatalysts using cuprous oxide (Cu₂O) thin films modified with a Ni overlayer. By tuning the amount of Ni electrodeposited on top of the Cu₂O, we determine the optimal ratio of Ni/Cu₂O for OER in alkaline solution with the best catalyst possessing an onset overpotential of only 150 mV. Surface characterization using XRD, SEM, EDS, and AFM indicates that the composition and morphology of the catalyst is highly dependent upon the amount of Ni electrodeposited, and these differences determine catalyst performance. In particular, the optimal catalyst contains a fairly uniform distribution of Ni and Cu₂O particles, suggesting that bimetallic sites facilitate efficient O₂ evolution.