Interfacial electron rearrangement: Ni activated Ni(OH)2 for efficient hydrogen evolution

The rational modulation of electronic structure is highly desirable to develop an efficient alkaline hydrogen evolution reaction (HER) catalyst for renewable energy applications. Metal hydroxide such as Ni(OH)2 has been proven useful for promoting alkaline HER, but the performance remains unsatisfactory. Herein, the electronic structure of Ni(OH)2 is modulated by the interfacial electron rearrangement between Ni-Ni(OH)2 heterojunction. Combined experiments with DFT simulations, the electrons of Ni species accumulate to the interfacial Ni-Ni(OH)2 sites, which modifies the d band center for promoting conversion of hydrogen intermediates and narrows the energy gap for boosting charge transfer in the HER process. Thus, the integrated electrode exhibits an efficient HER performance to drive 10 mA cm−2 at the overpotential of 72 mV with a low Tafel slope of 43 mV dec−1. Our work renders a valuable insight for understanding and rationally designing efficient catalysts in alkaline HER.