Experimental and Theoretical Insights into Transition-Metal (Mo, Fe) Codoping in a Bifunctional Nickel Phosphide Microsphere Catalyst for Enhanced Overall Water Splitting

The facile synthesis of efficient non-precious-metal-based bifunctional catalysts for overall water splitting is highly desirable from both industrial and environmental perspectives. This study reports the electrodeposition and characterization of a transition-metal (Mo, Fe)-codoped nickel phosphide (Ni3P:FeMo) bifunctional catalyst for enhanced overall water splitting in an alkaline medium. The Ni3P:FeMo catalyst exhibited outstanding electrocatalytic performance for both the hydrogen evolution reaction and oxygen evolution reaction with low overpotentials of -103 and 290 mV, respectively, at a high current density of 100 mA/cm(2) along with fast electrocatalytic kinetics. A full water-splitting electrolyzer consisting of a bifunctional Ni3P:FeMo catalyst required a low cell voltage of 1.48 V to attain a current density of 10 mA/cm(2) with excellent stability for more than 50 h. Density functional theory calculations provided insights into the microscopic mechanism of the effective modulation of the p- and d-band centers of the P and Ni active sites by the Mo and Fe codoping of Ni3P, thereby enhancing the bifunctional catalytic activity of Ni3P.

Automated summary

This study presents a transition-metal (Mo, Fe)-codoped nickel phosphide (Ni3P:FeMo) bifunctional catalyst for enhanced overall water splitting in an alkaline medium. The catalyst showed outstanding electrocatalytic performance for both the hydrogen evolution reaction and oxygen evolution reaction, with low overpotentials and fast electrocatalytic kinetics.