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

Tuning the electroactive surface species of electrocatalystsremainsa significant challenge for achieving highly efficient oxygen evolutionreactions. Herein, we propose an innovative in situ leaching strategy, modulated by cationic oxidation, to achieve activeself-reconstruction of these catalysts. Vanadium is introduced asa cation into Ni3S2 and oxidized under low oxidativepotential, leading to subsequent leaching into the electrolyte andtriggering self-reconstruction. The structural evolution from V-Ni3S2 to Ni-(OH)(2) and subsequently to NiOOHis identified by operando Raman as a three-step transition.In contrast, V-free Ni3S2 is unable to bypassthe thermodynamically predicted nickel oxysulfide products to transforminto active NiOOH. As a result, the self-restructured V-Ni3S2 only needs an ultralow overpotential of 155 mV at 10mA cm(-2), outperforming V-free Ni3S2 and many other advanced catalysts. This work provides newguidelines for manipulating in situ leaching to modulatethe self-reconstruction of catalysts.