Cationic Oxidative Leaching Engineering Modulated Self-Reconstruction of Nickel Sulfide for Superior Water Oxidation.

Tuning the electroactive surface species of electrocatalysts remains a significant challenge for achieving highly efficient oxygen evolution reactions. Herein, we propose an innovative leaching strategy, modulated by cationic oxidation, to achieve active self-reconstruction of these catalysts. Vanadium is introduced as a cation into NiS and oxidized under low oxidative potential, leading to subsequent leaching into the electrolyte and triggering self-reconstruction. The structural evolution from V-NiS to Ni(OH) and subsequently to NiOOH is identified by Raman as a three-step transition. In contrast, V-free NiS is unable to bypass the thermodynamically predicted nickel oxysulfide products to transform into active NiOOH. As a result, the self-restructured V-NiS only needs an ultralow overpotential of 155 mV at 10 mA cm, outperforming V-free NiS and many other advanced catalysts. This work provides new guidelines for manipulating leaching to modulate the self-reconstruction of catalysts.