In‐Situ Sulfuration of Ni(OH)2 to Heterostructured Ni3S2/Ni(OH)2@Ni Catalyst for Efficient Water Splitting

Abstract 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, Ni 3 S 2 /Ni(OH) 2 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, Ni 3 S 2 /Ni(OH) 2 ‐5h displayed the smallest overpotentials (237 mV@100 mA cm −2 and 360 mV@100 mA cm −2 ) for OER and HER at room temperature, along with low Tafel slopes of 62.0 mV dec −1 and 80.8 mV dec −1 respectively. Furthermore, working at high temperature Ni 3 S 2 /Ni(OH) 2 ‐5h exhibited even lower overpotential of 82 mV@100 mA cm −2 at 70 °C for OER and 325 mV@100 mA cm −2 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 Ni 3 S 2 and Ni(OH) 2 . 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.