Oxyanion-Assisted Bimetallic Sulfide Heterostructured Arrays for Versatile Industrial-Scale Seawater Splitting

Abstract

Industrial-scale hydrogen production from seawater holds great promise, but its development is limited by the high concentration of chloride ions (Cl–) in seawater. This study reports a novel transition metal-based bimetallic sulfide catalyst (NMS) that exhibits exceptional electrocatalytic kinetics, remarkable activity, and extraordinary operational stability in alkaline seawater electrolytes. The anion-exchange membrane seawater electrolyzer equipped with the NMS electrode achieves a current density of 100 mA cm–2 at a low cell voltage of 1.633 V (room temperature). Moreover, it maintains stable operation for 100 h at an industrial-grade 400 mA cm–2 with a minimal activity decay of 1.08%. Coupled with in situ characterization and theoretical calculations, this work elucidates the dynamic reconstruction mechanism of NMS during alkaline seawater electrolysis. It also elucidates the synergistic role of adsorbed molybdenum and sulfur oxyanions on the electrode surface, which form a protective layer restricting Cl– access to the electrode's active sites, effectively suppressing the competitive chlorine oxidation reaction (ClOR) and significantly enhancing electrode performance. This work offers a viable pathway for the industrial application of green hydrogen production using seawater and complex-component water sources.