Pulse-electrodeposited Ni–Fe–Sn films supported on Ni foam as an excellent bifunctional electrocatalyst for overall water splitting

The development of extremely active bifunctional non-noble electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is pivotal for water splitting but remains challenging. Herein, self-supported Ni–Fe–Sn electrocatalysts were fabricated on nickel foam (NF) through a simple and facile pulse electrodeposition process. Under optimal conditions, the prepared Ni–Fe–Sn electrocatalysts exhibited excellent bifunctional properties in alkaline medium and required ultralow overpotentials of only 27 and 201 mV for HER and OER, respectively, to reach the current density of 10 mA cm−2. Importantly, the same Ni–Fe–Sn electrocatalyst can be assembled as the anode and the cathode in a two-electrode system. It demanded a fairly low applied voltage of 1.55, 1.72, and 1.87 V to produce 10, 50, and 100 mA cm−2, respectively, and exhibited excellent long-term stability. The excellent electrocatalytic water splitting performance of the Ni–Fe–Sn film was mainly associated with its intrinsic catalytic activity derived from the modulation of the electronic structures among Ni, Fe, and Sn by using the appropriate atomic ratio of Ni: Fe: Sn.