Regulating the Local Spin State and Band Structure in Ni₃S₂ Nanosheet for Improved Oxygen Evolution Activity

Abstract The separate modulation of the adsorption of *O and *OOH is challenging in oxygen evolution reaction (OER), which results in a large overpotential and slow kinetics. To balance the adsorption of the two active species, here, a way to regulate the local spin state and band structure simultaneously in Ni 3 S 2 nanosheets is reported. The adequate doping of W heteroatoms causes the electron depletion from the Ni active site, which modulates the spin state of e g electrons, weakening the adsorption of *O. Additionally, the introduction of S vacancies contributes to the upshift of the d band center, which strengthens the adsorption of *OOH. In this manner, the adsorption of Ni 3 S 2 for the active intermediates is optimized, resulting in a considerably improved overpotential of 246 mV at 100 mA cm −2 and a Tafel slope of 66 mV dec −1 . This work provides insights into the exploration of OER catalysts through synergistic modulation of the spin state and the band structure.