Electrochemical reconfiguration of iron-modified Ni₃S₂ surface induced oxygen vacancies to immobilize sulfate for...

There is an urgent need for highly active, durable, and low-cost electrocatalysts to overcome the shortcomings of high overpotential in the oxygen evolution reaction (OER) process. In this work, the nickel-iron hydroxysulfate rich in sulfate and oxygen vacancies (SO₄^2-@Fe-NiOOH-O_v/NiS) is legitimately constructed. SO₄^2-@Fe-NiOOH-O_v/NiS only requires a low overpotentials of 190 mV and 232 mV at 10 mA cm^-2 and 100 mA cm^-2 current densities in 1 M KOH, with excellent stability for 200 h at 100 mA cm^-2 current density. In situ Raman spectroscopy and Fourier transform infrared spectroscopy demonstrated the stable adsorption of more SO₄^2- on the surface of catalyst. Density functional theory calculations testify surface reconstruction, doped Fe and oxygen vacancies significantly reduced the adsorption energy of sulfate on the surface. More importantly, the formation of *OOH to O₂ is facilitated by the highly hydrogen bonding between SO₄^2- and *OOH, accelerating the OER process.