In Situ Growth of Nickel Sulfide on Laser-Processed Co-Induced Ni Foam for Enhanced Electrochemical Water Splitting

Transition metal chalcogenides are promising low-cost alternatives to precious metal catalysts for electrochemical water splitting, but their performance and stability still require significant improvement. Here, we report a novel and highly effective strategy for fabricating a robust, bifunctional electrocatalyst by combining laser-induced cobalt doping with in situ chemical vapor deposition (CVD) of a NiS/NiS2 heterostructure on porous Ni foam. This approach leverages the synergistic effects between the highly active Co sites and the NiS/NiS2 heterojunction, while the laser treatment enhances the surface area and promotes strong adhesion. The resulting Co–NiS/NiS2 electrode exhibits outstanding performance in 1 M KOH for both electrochemical hydrogen and oxygen generation processes, requiring an overpotential of 128 and 284 mV to achieve a 10 mA cm–2 current density, respectively. For overall water splitting, the bifunctional catalyst requires a cell potential of 1.65 V at 10 mA cm–2, which is comparable with noble metal-based electrocatalysts. Furthermore, the catalyst also shows remarkable durability, sustaining its activity for more than 40 h of continuous operation. Overall, this study presents a scalable and efficient approach for developing advanced, affordable electrocatalysts suited for clean energy technologies.