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

Introducing oxygen vacancies (VO) can significantly improve the performance of electrocatalytic oxygen evolution (OER) for layered double hydroxides. However, introducing VO requires harsh conditions, such as high temperature and high pressure, so the controllable introduction of VO is still challenging. In this study, Ni–Fe layered double hydroxide with a higher concentration of VO (Ni3Fe–S10) 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 Ni3Fe–S10 has abundant VO. At 10 mA cm–2, the overpotential of the Ni3Fe–S10 catalyst electrode reaches 235 mV, and the electrode can work stably for 45 h. In situ electrochemical Raman results show that NiOOH generated by Ni3Fe–S10 electrochemical reconstruction is the actual active site. The theoretical results show that introducing a reasonable VO concentration can improve the inherent conductivity of the Ni3Fe–S10 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.