CoNi-phosphides with iron incorporation effectively boost hydrogen evolution reaction and oxygen evolution reaction for overall water splitting

Rational design of high-efficiency, durable and cost-effective electrocatalysts for H 2 production is essential to accelerate hydrogen production from fundamental experiments to practical industrial applications. Herein, cobalt-nickel-iron phosphides are constructed on Ni foam (CoNiFeP@NF) via a simple one-step electrochemical deposition method as self-supported electrodes for efficiently water splitting. The introduction of Fe element significantly enhances the catalytic properties of CoNiP@NF electrode for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Additionally, the optimal HER and OER electrodes are obtained by adjusting the Fe 3+ concentration at 0.1 ( [email protected] ) and 0.15 M ( [email protected] ), respectively. Benefiting from the modulation of the electronic structure of CoNiP by the Fe element, [email protected] and [email protected] electrodes only require the overpotentials (η) of 48 mV for HER and 223 mV for OER to reach the current density of 10 mA cm −2 , superior to the reference CoNiP@NF electrode (η 10, HER  = 89 mV, η 10, OER  = 333 mV). Subsequently, the electrolyzer constructed by [email protected] as cathode and [email protected] as anode exhibits excellent overall water splitting performance with a cell voltage of 1.56 V at a current density of 10 mA cm −2 . This work provides a convenient and effective strategy for regulating the catalytic activity of bifunctional phosphide catalysts for water splitting.