Novel Ni2P-microporous nickel phosphite supported on nitrogen-doped graphene composite electrocatalyst for efficient hydrogen evolution reaction.

ABSTRACT

Transition metal phosphides are regarded as promising hydrogen evolution reaction (HER) electrocatalysts for water splitting. An efficient mass-transfer mechanism can be promoted through constructing microporous structures. In addition, introducing carbon materials as carriers to form interface interactions is beneficial for increasing electronic conductivity so as to promote the catalytic activity further. In this work, a nitrogen-doped graphene (NGO)-supported microporous nickel phosphide-nickel phosphite (Ni2P-Ni11(HPO3)8(OH)6@NGO, Ni2P-MPH@NGO), where Ni2P nanoparticles uniformly fill the micropores of Ni11(HPO3)8(OH)6and then are supported on two-dimensional NGO via a simple two-step method, has been studied as a novel efficient electrocatalyst for HER. Compared with carbon nanotubes and graphene as carbon-based carriers, the optimized Ni2P-MPH@NGO catalyst shows excellent HER performance with a smaller overpotential, lower Tafel slope and long-term catalytic durability under acid conditions. The results demonstrate that NGO can enhance the catalytic activity of Ni2P-MPH@NGO efficiently. The results show that the synergistic effect of the microporous structure of Ni11(HPO3)8(OH)6and NGO effectively improves the catalytic activity of the Ni2P-MPH@NGO composite catalyst, which provides a promising strategy for the design of a new low-cost and high-efficiency HER electrocatalysts.