Vacancy defect-rich NiS2 nanosheets induced by Ce-doping for highly efficient water and urea oxidation reaction

The feasibility of enhancing the electrocatalytic performance of sulfides is demonstrated through element doping and vacancy engineering. However, the investigation on the reaction mechanisms of catalyst doping and defects related to oxygen evolution reaction (OER) still faces significant challenges. In this work, a Ce-doped NiS 2 supported on carbon cloth (Ce-NiS 2 @CC) with abundant sulfur vacancy defects was successfully developed through a sequential two-step hydrothermal and high-temperature vulcanization strategy. The results demonstrate that the obtained Ce-NiS 2 @CC catalyst exhibits excellent electrochemical performance for both OER and urea oxidation reaction (UOR). It requires only 1.40 and 1.28 V to achieve a current density of 10 mA/cm 2 for OER and UOR, respectively. Furthermore, the Tafel slopes observed for OER and UOR are noteworthy at 40.2 and 58.3 mV/dec, respectively, suggesting enhanced kinetics and superior catalytic performance. Additionally, the stability tests conducted on the catalyst reveal that the Ce-NiS 2 @CC possesses exceptional electrochemical long-term stability, making it a highly reliable and durable option for various applications. Density functional theory calculations and in situ Raman results demonstrate that Ce doping and sulfur vacancy synergistically promote surface reconstruction to form Ni Ⅲ –O species, modulate the local charge distribution near the Ni site, thereby facilitating the adsorption and activation of water molecules, and consequently accelerating the kinetics of OER. This study systematically investigated the impact of metal doping and vacancy defects on electrocatalytic performance, offering insights into electronic structure regulation and performance optimization for efficient electrocatalysts.