Self-generated oxygen radical species accelerate the alkaline oxygen-evolving reaction

The oxygen evolution reaction (OER) in electrochemical water electrolysis typically undergo high overpotentials and slow kinetics, greatly hindering the progress of the electrolytic water industry. Motivated by this, we successfully synthesized two types of NiCoFe/Fe1.63Ni1.82Co5.6S8 as OER catalysts (O-Cat-1 and O-Cat-2). As anticipated, the Ni/O-Cat-1/Ni electrode exhibits a lower overpotential (310 mV at 100 mA cm(-2)) and a smaller Tafel slope compared to Ni/O-Cat-2/Ni, along with a 10-day electrocatalytic lifespan. Specifically, during the stability test, the maximum driving current reaches 4.29 times the initial current. This increase can be attributed to the presence of self-generated oxygen radicals within the electrocatalytic system, as evidenced by the durability test conducted with the introduction of H2O2 into the electrolyte. These radicals may be induced by thermal effects, humid summer environments, or elevated O-3 concentrations in the solution. Additionally, the formation of the metal oxides, hydroxides, and oxyhydroxides species on the electrode surface also enhances the OER efficiency. Substantially, the unveiling of the self-generated oxygen radical mechanism offers a novel pathway for developing a highly efficient electrocatalytic system for OER.