Single‐Source Assisted Synthesis of Spin‐Regulated Cobalt/Nickel Co‐Doped Pyrite FeS ₂ : Enhanced Spin Channels in Co‐Ni‐Fe Oxyhydroxides for Efficient Alkaline Oxygen Evolution Reaction

ABSTRACT Controlling spin states in earth‐abundant electrocatalysts is substantial for enhancing the oxygen evolution reaction (OER). However, managing spin in pyrite‐type disulfides remains challenging. In this study, a spin‐tuned Co/Ni‐FeS 2 is synthesized via pyrolysis of molecular metal‐thiolate complexes in a sulfur‐rich, inert environment. This approach enables precise dopant control, atomic‐scale uniformity, and scalable production that surpasses those of traditional hydrothermal or sulfidation methods, offering a versatile platform for designing multi‐metal pyrites. Structural and spectroscopic analyses confirm the successful substitution of iron by cobalt and nickel, demonstrating that co‐doping modifies spin and electronic states. This results in increased spin polarization, improved electron transport, and lower energy barriers for oxygen‐oxygen bond formation. In situ X‐ray absorption spectroscopy and post‐catalytic examinations reveal controlled reconstruction into mixed‐metal oxyhydroxides containing high‐valence iron, cobalt, and nickel as active centers. The optimized 6% Co, 2% Ni‐FeS 2 shows excellent OER performance, with an overpotential of 193 mV at 10 mA cm −2 , a Tafel slope of 55 mV dec −1 , and high durability. Density functional theory suggests that co‐doping enhances spin‐selective pathways and adsorption energetics, providing a solid foundation for spin‐regulated pyrite electrocatalysts in water splitting and other clean energy applications.