Interfacing nickel with molybdenum oxides as monolithic catalyst to accelerate alkaline hydrogen electrocatalysis with robust stability

Abstract

Engineering active and robust catalysts for hydrogen evolution and oxidation reactions (HER and HOR) are of importance for the realization of green hydrogen economy. To make catalysts economically competitive for large−scale applications, even−increasing interests have been shifted to designing nonprecious materials for HER and HOR with active and robust performance. Herein, with the guidance of interface engineering, the monolithic catalyst of Ni−MoO2 heterojunctions on nickel foam (Ni−MoO2/NF) was deliberately fabricated by the in−situ corrosion−growth under hydrothermal condition and following thermal−reduction procedure, which exhibits extraordinary HER and HOR performance, for instance, nearly Pt−like catalytic activities, robust long−term durability even under large current density, and superior Faradaic efficiency in alkaline electrolyte. Coupling with the active urea oxidation catalyst of NiMoO4/NF as anode (treating the hydrothermal product in Ar atmosphere), the assembled overall urea splitting electrolyzer with Ni−MoO2/NF as cathode affords the lower voltage of 1.53 V at 20 mA cm−2, and keeps this performance overall 120 h without decay. The systematic physicochemical characterization and electrochemical investigations reveal that the heterointerface-induced charge redistribution, individual electrocatalytic functions, superaerophobic/superhydrophilic electrode surface, and monolithic electrode structure together collaborate to the efficient catalytic activity and stability under larger current density.