A superhydrophilic self-supported nickel/terbium oxide electrode for the alkaline hydrogen evolution reaction at high current density

Abstract

The development of highly efficient and robust non-noble-metal electrocatalysts for the alkaline hydrogen evolution reaction at high current density is the key for industrialization of anion exchange membrane water electrolysis. This work develops a new-style superhydrophilic self-supported Ni/Tb₂O₃ electrocatalyst, which shows excellent catalytic performance for the alkaline HER, with a low overpotential of 71.4 mV at −10 mA cm⁻², a low Tafel slope of 43.9 mV dec⁻¹, and robust stability at a high current density of 500 mA cm⁻². The incorporated Tb₂O₃ with high oxophilicity promotes the water dissociation, thereby facilitating the Volmer step of the alkaline HER. The electronic redistribution in the Ni/Tb₂O₃ heterostructure optimizes the hydrogen adsorption energy of Ni, thus synergistically accelerating the HER kinetics. Moreover, the thermodynamically stable Tb₂O₃ mitigates the oxidation corrosion of Ni, thus improving its catalytic stability. In addition, the superhydrophilic self-supported electrode structure of Ni/Tb₂O₃ expedites the electron conduction and accelerates the gas bubble release timely for the production of H₂, further enhancing the catalytic activity and stability at high current density.