Raman Spectroscopic Observation of Electrolyte-Dependent Oxygen Evolution Reaction Intermediates in Nickel-Based Electrodes

Oxygen evolution reaction (OER) is the counterpart in hydrogen production by water electrolysis. Further challenges have been required to bypass the energy consumption processes in the OER. It is still important to unveil the OER intermediates toward effective green hydrogen production. In this study, we conducted in situ Raman observation of the OER intermediates over Ni nanohole-array electrodes in the various electrolyte conditions. Ni nanohole-array electrodes were prepared with interference exposure methods. Intense Raman peaks were observed from Ni–OH, Ni-OOH, and active oxygen species as the OER intermediates. The OER behavior can be classified with the reactants, such as OH^– and H₂O. The presented study demonstrates the importance of the electrolyte for the designing active OER catalysis for the next generation energy society.