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

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. The oxophilic Tb2O3 promotes the dissociation of water and optimizes the hydrogen adsorption energy of metal Ni, synergistically accelerating the overall HER kinetics of Ni/Tb2O3.