Sodium Sulfite Intercalation in Ni–Fe Layered Double Hydroxide Nanosheets to Form Oxygen Vacancies for Electrocatalytic Oxidation of Water

Introducing oxygen vacancies (V O ) can significantly improve the performance of electrocatalytic oxygen evolution (OER) for layered double hydroxides. However, introducing V O requires harsh conditions, such as high temperature and high pressure, so the controllable introduction of V O is still challenging. In this study, Ni–Fe layered double hydroxide with a higher concentration of V O (Ni 3 Fe–S 10 ) was prepared under mild conditions using a chemical reduction method in which sodium sulfite was used as an intercalation agent. The results of high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and electron paramagnetic resonance show that Ni 3 Fe–S 10 has abundant V O . At 10 mA cm –2, the overpotential of the Ni 3 Fe–S 10 catalyst electrode reaches 235 mV, and the electrode can work stably for 45 h. In situ electrochemical Raman results show that NiOOH generated by Ni 3 Fe–S 10 electrochemical reconstruction is the actual active site. The theoretical results show that introducing a reasonable V O concentration can improve the inherent conductivity of the Ni 3 Fe–S 10 catalyst, optimize the adsorption/desorption barrier of oxygen-containing intermediates, and accelerate the chemical reaction kinetics of the OER. This study provides a reference for designing high-performance NiFe-LDHs OER catalysts.