Manipulating electronic regulation of nickel sulfide for boosting water oxidation

The development of non-precious metal oxygen evolution reaction (OER) electrocatalysts is of critical for industrial-scale hydrogen production, but remains challenging. In this work, we report a novel Bi-doped nickel sulfide (Bi–Ni 3 S 2 ). The incorporation of Bi dopant not only induces the oxidation of d-orbital electrons of Ni, but also decreases the electron population in e-orbitals, thereby optimizing the electronic reconfiguration of Ni 3 S 2 . In-situ Raman spectroscopy further reveals that Bi dopant could manipulate local electronic micro-environment of Ni sites in Ni 3 S 2 -based electrocatalysts through orbital hybridization, thereby promoting the formation of high valent hydroxyl oxides. The optimized Bi–Ni 3 S 2 catalyst exhibits superior catalytic performance, achieving a current density of 10 and 500 mA cm −2 at an overpotential of only 256 and 328 mV in 1.0 M KOH. Importantly, an assembled electrolyzer merely requires 2.08 V to deliver an industrial-grade current density of 1000 A cm −2 while maintaining stable operation for over 200 h.