Designing Hybrid NiP2/NiO Nanorod Arrays for Efficient Alkaline Hydrogen Evolution.

Transition-metal phosphides (TMPs) have lately drawn intensive attention because of their noble metal-free properties and high catalytic activities for the hydrogen evolution reaction (HER). The current research mainly focuses on the development of TMPs toward the HER in acidic solutions; however, less efforts have been directed to specifically design TMPs for alkaline HER. Here, we design a new bi-functional metal phosphide-oxide catalyst to facilitate the overall multistep HER process in alkaline environments. In this new catalytic system, oxygen-vacancy-rich NiO provides abundant active sites for dissociation of water, and the negatively charged P species in NiP2 facilitate adsorption of hydrogen intermediates. The resulting hybrid NiP2/NiO NRs show excellent alkaline HER catalytic activity and stability. Our work demonstrates that it is highly promising to engineer multiple components in hybrid catalytic systems to enhance the overall reaction kinetics and thus achieve improvements in catalytic performance.