Restricting the over-oxidation of active sites in high-entropy electrocatalysts towards ultra-stabilized oxygen evolution in alkaline water electrolysis

Abstract

The compatibility between activity and stability of high-entropy electrocatalysts for the oxygen evolution reaction (OER) is crucial for their widespread application in alkaline water electrolysis. While activating lattice oxygen with high-valence metals may boost the catalytic activity, it also tends to increase oxygen vacancies and cation dissolution, which exacerbates the conflict phenomenon that has been seen. Low ionic electronegativity and inert Cu-incorporating nanoporous MnFeCoNiOOH (np-MnFeCoNiOOH) was designed in this study to serve as an ultra-long stable alkaline OER electrocatalyst without the need for noble metals. Np-MnFeCoNiCuOOH displayed a low overpotential (176 mV) and superb stability over the 5500 h durability test at 500 mA cm⁻². The OER energy barrier was lowered by the enhanced adsorption of oxygen intermediates to active Ni sites. Moreover, low ionic electronegativity components limit the electrocatalytic metal active center's over-oxidation, which lowers the lattice oxygen activity and continuously reconstructs the electrode surface during the OER process, prolonging the catalyst's lifespan.