Surface SO_x Species Stabilized Metal-Oxygen Bonds in PtNi Nanoalloy for Highly Efficient and Durable Seawater Hydrogen Production

Regulation of metal-oxygen (M-O) bonds and incorporation of sulfur are promising approaches for designing electrocatalysts for efficient hydrogen production from seawater. However, the durability of these catalysts is limited by the instability of M-O bonds under cathodic conditions and poisoning caused by the uncontrolled introduction of sulfur. In this study, a "killing two birds with one stone" strategy was developed for creating efficient hydrogen production electrocatalysts that involves anchoring PtNi nanoparticles on hydroxyl-functionalized carbon nanotubes and modifying the surface with SO_x species (S-PtNi/CNTs) via a one-pot hot-injection-combined wet-chemical synthesis protocol. In this material, hydroxyl-functionalized CNTs stabilize PtNi through M-O bonding, while SO_x species tune the electronic structure of Pt and enhance M-O bond stability. Consequently, S-PtNi/CNTs exhibits outstanding hydrogen production performance in alkaline seawater, delivering a 5.4-fold increase in mass activity and a 21-fold increase in specific activity compared to commercial Pt/C, along with remarkable stability over a 1000-h operation period. Furthermore, S-PtNi/CNTs significantly outperform commercial Pt/C in both a photovoltaic-electrocatalysis electrolyzer and an anion-exchange-membrane water electrolysis system. The results of in situ spectroscopy and theoretical calculations confirm that SO_x species stabilization of M-O bonds and improved chloride ions resistance are responsible for the superior performance of S-PtNi/CNTs.