Bio-Magnetically Tailored Spin Configurations in Ni-Doped FeS Pre-Catalysts for Alkaline Water Splitting

Oxygen evolution reaction (OER) with spin-forbidden transitions is a key bottleneck in efficient water splitting. Here, a magnetic field (MF)-assisted microbial corrosion strategy is developed to construct bimetallic sulfide nanosheets with a tunable high-spin (HS) state. Experimental and Theoretical calculations reveal that HS Ni doping enhances the structural stability of FeS and promotes the formation of active phases. As a result, the obtained NiS@FeS/HS catalyst exhibits excellent OER activity, requiring an overpotential of only 259 mV at 100 mA cm^-2. More importantly, the Ni-S and Fe-S/HS coordination makes the reconstructed Ni(Fe)OOH active phase retain the HS electronic structure during the OER process. The inherited HS state promotes spin-polarized charge transfer and suppresses lattice-oxygen participation, thereby enhancing the OER catalytic activity and structural stability. Furthermore, the assembled NiS@FeS/HS (+)||NiFeP/HS (-) anion exchange membrane electrolyzer requires 1.70 V@200 mA cm^-2 and operates stably for over 1000 h. This work provides an effective bio-magnetic strategy to construct metal sulfide pre-catalysts with regulated spin states, which can inspire broad interest in the interdisciplinary integration of traditional corrosion engineering, physics, and emerging energy technologies.