Tuning the Band Structure of Co₃Sn₂S₂ Topological Semimetal for Oxygen Evolution in Alkaline Electrolytes

Co₃Sn₂S₂ (CSS) possesses robust surface states and high conductivity derived from Co atoms with Weyl points located only 60 meV above the Fermi level (E_f), revealing the probability of tuning the electronic band structure of CSS by doping with transition metal atoms. Here, Fe, Ni, and Cu atoms have been successfully incorporated into CSS, which turns out that the Fe_0.1-CSS possesses better activity than CSS and IrO₂ with an overpotential of 298 mV to reach the current density of 10 mA cm^-2 and a Tafel slope of 358.3 mV dec^-1 in 1 M KOH. The Fe_0.1-CSS also shows better activity and stability than IrO₂ as an anode for the anion exchange membrane water electrolyzer in 1 M KOH. Besides, the density functional theory results indicate that the band structure of CSS is adjusted by the incorporation of transition metal atoms, which is related to the regulation of E_f and thus the variation in electrolytic performance. Our findings provide a strategy to further engineer the activity of a topological semimetal, which provides a direction toward material design for catalysis and beyond.