In Situ Electrochemical Activation of Fe/Co-Based 8-Hydroxyquinoline Nanostructures on Copper Foam for Oxygen Evolution

Oxygen evolution reaction (OER) is an important step in water splitting. However, it suffers from slow kinetics due to the multistep proton-coupled electron-transfer processes. Electrochemical activation is often used to obtain highly effective electrocatalysts with various precatalysts including sulfides and metal–organic frameworks, while details for the related phase transformation are often overlooked. Herein, micro-/nanoscale building blocks of Fe/Co-based 8-hydroxyquinoline compounds were loaded on a copper foam acting as a precatalytic electrode for oxygen evolution. The obtained precatalytic electrode can be activated in situ and shows an excellent catalytic activity for OER with an overpotential of 247 mV for 10 mA cm–2 in 1.0 M KOH. The phase transformation of the catalytic electrode during the OER operation was carefully investigated. The results would help the understanding of electrocatalyst activation and provide some hints for the development of advanced electrocatalysts.