Fe-doped (MoFeNi)3S2 Bifunctional Electrocatalyst with Halide Ion Corrosion Resistance for Efficient Brackish Water Electrolysis

Abstract

Brackish water is an attractive feedstock for large-scale hydrogen production, but the high concentration of Cl⁻ ions causes severe electrode corrosion and efficiency loss. Here, Fe-doped molybdenum sulfide was grown on nickel foam by a hydrothermal route to address this issue ((MoFeNi)₃S₂). The introduction of Fe strengthens the bonding within the sulfide framework, which helps to stabilize the structure and reduce the damage caused by halogen ions. In parallel, Fe also tunes the electronic state of the active sites, leading to higher catalytic activity. In 1.0 mol L^− 1 KOH + 0.5 mol L^− 1 NaCl electrolyte, the catalyst delivers bifunctional activity for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), achieving 10 mA cm^− 2 at an overpotential of 225 mV (OER)/53 mV (HER), and retaining OER stability for 384 h at 1000 mA cm^− 2. A full alkaline electrolyzer with (MoFeNi)₃S₂ electrodes operates continuously for over 264 h, highlighting its promise for overall water splitting in saline environments. This research provides a promising theoretical approach for the development of corrosion-resistant catalysts that can efficiently and stably produce hydrogen through alkaline saline water electrolysis.