Coupling sulfion oxidation with hydrogen evolution via an amorphous NiMo sulfide for energy and resource recovery

Replacing the oxygen evolution reaction (OER) with the sulfion oxidation reaction (SOR) offers an attractive route for energy-saving hydrogen production and sulfion-containing wastewater valorization. However, the sulfur-induced catalyst corrosion and passivation greatly hinder SOR efficiency. Herein, an amorphous nickel - molybdenum sulfide grown on nickel foam (NiMo-S/NF) was developed as a robust bifunctional electrocatalyst for both SOR and hydrogen evolution reaction (HER). The amorphous structure provides abundant unsaturated active sites and facilitates reactant access. The electronic interplay between Ni and Mo modulates the electronic environment of Ni sites, resulting in optimized electronic structures and accelerated reaction kinetics. For SOR, only 0.45 ± 0.02 V (vs. RHE) was required to achieve the current density of 500 mA cm^-2 and maintain a long-period stability over 120 h at 100 mA cm^-2. Moreover, coupling HER and SOR in a two-electrode flow electrolyzer, a cell voltage of merely 0.91 ± 0.01 V is enough to drive the current density of 500 mA cm^-2, yielding high and stable production rates of approximately 180.54 ± 1.01 g h^-1 m^-2 for sulfur and 145.09 ± 0.29 g h^-1 m^-2 for H₂, respectively. This work well demonstrates the promise of amorphous bimetallic sulfides in the integrated energy and resource recovery systems from the sulfion-containing wastewater.