Defect Engineering in Sn-Doped NiS/Ni3S2 Nanostructures for Oxygen Evolution Reaction

Abstract

Nickel-based sulfides have been proven to be excellent oxygen evolution reaction (OER) electrocatalysts due to their excellent electrical conductivity, but their poor stability hinders their application in practical applications. To address this issue, defect engineering has been proposed as a viable strategy to enhance the electronic structure of the catalyst and further boost the OER performance. Herein, a MOF-derived Sn-doped NiS/Ni₃S₂ nanostructure grown in situ on nickel foam (Sn–Ni_xS_y/NF) has been designed as an active OER electrocatalyst. The morphology of the material was significantly impacted by the addition of the Sn elements, nanorods modified with nanoparticles providing more active sites. Moreover, the introduction of Sn elements induced the generation of sulfur vacancies (V_s), enhanced electron transfer, promoted electron redistribution, and increased the charge transfer rate. All of these endow the Sn–Ni_xS_y/NF-T with exceptionally low overpotentials of 104 and 286 mV to achieve a current density of 10 and 100 mA cm^–2 for OER. Moreover, the Sn–Ni_xS_y/NF-T showed long-term stability, maintaining 100 h at current densities of 100 mA cm^–2. In short, this work opened a route for engineering defects to boost the OER.