Nitrogen Disturbance Awakening the Intrinsic Activity of Nickel Phosphide for Boosted Hydrogen Evolution Reaction.

Nickel phosphide (Ni 2 P) has emerged as a promising candidate to substitute Pt-based catalysts for hydrogen evolution reaction (HER) due to the hydrogenase-like catalytic mechanism and concomitantly low cost. However, its catalytic activity is still not comparable to that of noble-metal-based catalysts, and innovative strategies are still urgently needed to further improve its performance. Herein, a self-supported N-doped Ni 2 P on Ni foam (N-Ni 2 P/NF) was rationally designed and fabricated through a facile NH 4 H 2 PO 2 -assisted gas-solid reaction process. As an HER catalyst in alkaline medium, the obtained N-Ni 2 P/NF revealed excellent electrocatalytic performance with a distinctly low overpotential of 50 mV at 10 mA cm -2 , a small Tafel slope of 45 mV dec -1 , and long-term stability for 25 h. In addition, the spectroscopic characterizations and density functional theory calculations confirmed that the incorporation of N regulated the original electronic structure of Ni 2 P, enhanced its intrinsic catalytic property, optimized the Gibbs free energy of reaction intermediates, and ultimately promoted the HER process. This work provides an atomic-level insight into the electronic structure modulation of metal phosphides and opens an avenue for developing advanced transition metal phosphides-based catalysts.