In-Situ Sulfuration of Ni(OH) to Heterostructured NiS/Ni(OH)@Ni Catalyst for Efficient Water Splitting.

The exploring and developing non-precious transition metal-based catalysts for practical water electrolysis with the low cost, high efficiency and easy macroscopic preparation was still a challenge. Herein, NiS/Ni(OH) heterojunction with different sulfuration time was proposed and hydrothermally synthesized using a simple two-step approach, which served as a bifunctional electrocatalyst for water splitting in alkaline solution at industrial temperature. Among these catalysts, NiS/Ni(OH)-5h displayed the smallest overpotentials (237 mV@100 mA cm and 360 mV@100 mA cm) for OER and HER at room temperature, along with low Tafel slopes of 62.0 mV dec and 80.8 mV dec respectively. Furthermore, working at high temperature NiS/Ni(OH)-5h exhibited even lower overpotential of 82 mV@100 mA cm at 70 °C for OER and 325 mV@100 mA cm at 60 °C for HER. The excellent performance was ascribed to the heterojunction accelerating the charge transfer, hierarchical interconnected structure promoting the mass transfer and the synergistic effect between the components of NiS and Ni(OH). This work could provide a promising route for promoting the electrocatalytic performance of Ni-based catalyst with a simple sulfuration method for industrial water splitting, which could expand to other non-noble metal-based materials for enhancing the electrocatalytic activities.