Ultra-low palladium engineered nickel sulfide heterostructure supported on 3D nickel foam as a highly efficient and stable electrocatalyst for water oxidation

Electrochemical water splitting (EWS) has been a crucial process in the production of green fuels (oxygen and hydrogen) for a sustainable energy economy. One of the key processes in the EWS is water oxidation or the oxygen evolution reaction (OER). It is highly desirable to create cost-effective, efficient, and robust electrocatalysts for OER. Here, we present ultra-low Pd doped NiS-NiS₂ heterostructure on NF (0.1PdNiS/NF) grown in-situ by acid etching followed by a simple hydrothermal sulfurization method for excellent OER electrocatalytic activity in alkaline media. Interestingly, low overpotential of 275 mV is required for the 0.1PdNiS/NF to achieve a current density of 10 mAcm⁻², which is less than both NiS/NF (385 mV) and commercial RuO₂/NF (370 mV). Because of the strong electronic interaction between Pd and NiS, 0.1PdNiS/NF has a small Tafel slope of 65 mV/dec and has shown excellent durability for approximately 14 h. Therefore, the findings described above provide significant insights in the design of high-performance OER catalysts with ultra-low precious metal loading.