In Situ Carbon Thermal Reduction to Enrich Sulfur‐Vacancy in Nickel Disulfide Cathode for Efficient Synthesizing Hydrogen Peroxide

Abstract Transition metal catalysts are widely used in the 2e ⁻ ORR due to their cost‐effectiveness. However, they often encounter issues related to low activity. Defect engineering are used on developing highly active catalysts, which can effectively modify active sites and promote electron transfer. Here, carbon‐coated Ni ₃ S ₂ (Ni ₃ S ₂ @C), where the additional sulfur vacancies (V _S ) is prepared induced by the carbon layer is coupled with active nickel sites. Through in situ and ex situ experiments combined with DFT calculations, it is demonstrated that the carbon layer can regulate the quantity of V _S in Ni ₃ S ₂ . Materials with a higher concentration of V _S exhibit enhanced 2e ⁻ ORR activity and higher H ₂ O ₂ selectivity. In situ Raman spectroscopy confirms that Ni serves as the key active site in this catalyst. DFT calculations indicate that the OOH binding energy (ΔG) decreases with an increase in the number of V _S , favoring the protonation of *OOH to generate H ₂ O ₂ . Upon performance testing, the average H ₂ O ₂ selectivity is 92.3%, with the highest yield reaching up to 3860 mmol gcat ⁻¹ h ⁻¹ . It is noteworthy that Ni ₃ S ₂ @C exhibits high stability, with only a slight decrease in 2e ⁻ pathway selectivity after 5000 cycles of ADT.