Phosphorus Vacancies that Boost Electrocatalytic Hydrogen Evolution by Two Orders of Magnitude.

Vacancy engineering is an effective strategy to manipulate the electronic structure of electrocatalysts to improve their performance, but few reports focus on phosphorus vacancies (Pv). Herein, the creation of Pv in metal phosphides and investigation of their role in alkaline electrocatalytic hydrogen evolution reaction (HER) is presented. The Pv-modified catalyst requires a minimum onset potential of 0 mV vs. RHE, a small overpotential of 27.7 mV to achieve 10 mA cm-2 geometric current density and a Tafel slope of 30.88 mV dec-1 , even outperforms the Pt/C benchmark (32.7 mV@10 mA cm-2 and 30.90 mV dec-1 ). This catalyst also displays superior stability up to 504 hours without any decay. Experimental analysis and density functional theory calculations suggest Pv can weaken the hybridization of Ni 3d and P 2p orbitals, enrich the electron density of Ni and P atoms nearby Pv, and facilitate H* desorption process, contributing to outstanding HER activity and facile kinetics.