Amorphous/Crystalline NiFeS@Ni0.85Se supported on nickel foam as bifunctional electrocatalysts for efficient water splitting

Abstract

The synthesis of low-cost transition metal bifunctional electrocatalysts that can replace noble metals is crucial for realizing high efficiency hydrogen production from industrial water splitting. Herein, a novel binder-free amorphous/crystalline NiFeS@Ni_0.85Se bifunctional electrocatalyst material has been fabricated on nickel foam (NF) via a straightforward two-step electrodeposition method. The electrode features a unique structure in which NiFeS nanosheets of uniform size grow on Ni_0.85Se microspheres, thus providing more active sites. It exhibits a minimal overpotential of 63 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER) and 311 mV at 100 mA cm⁻² for oxygen evolution reaction (OER). Impressively, when assembled into an electrolytic cell, the electrocatalyst can reach 10 mA cm⁻² at just 1.51 V and remains stable for 220 h. Additionally, at 1.68 V, the catalyst reaches 50 mA cm⁻² and maintains stable operation for 140 h, demonstrating outstanding water splitting potential. This paper presents a composite material that combines the crystalline and amorphous states, allowing them to complement each other and jointly promote catalytic performance.