Induced Manipulation of Atomically Dispersed Cobalt through S Vacancy for Photocatalytic Water Splitting: Asymmetric...

It is still a challenge to construct single-atom level reduction and oxidation sites in single-component photocatalyst by manipulating coordination configuration for photocatalytic water splitting. Herein, the atomically dispersed asymmetric configuration of six-coordinated Co-S₂O₄ (two exposed S atoms, two OH groups, and two Co─O─Zn bonds) suspending on ZnIn₂S₄ nanosheets verified by combining experimental analysis with theoretical calculation, is applied into photocatalytic water splitting. The Co-S₂O₄ site immobilized by Vs acts as oxidation sites to guide electrons transferring to neighboring independent S atom, achieving efficient separation of reduction and oxidation sites. It is worth mentioning that stabilized Co-S₂O₄ configuration show dynamic structure evolution to highly active Co-S₁O₄ configuration (one exposed S atom, one OH group, and three Co─O─Zn bonds) in reaction, which lowers energy barrier of transition state for H₂O activization. Ultimately, the optimized photocatalyst exhibits excellent photocatalytic activity for water splitting (H₂: 80.13 µmol g^-1 h^-1, O₂: 37.81 µmol g^-1 h^-1) and outstanding stability than that of multicomponent photocatalysts due to dynamic and reversible evolution between stable Co-S₂O₄ configuration and active Co-S₁O₄ configuration. This work demonstrates new cognitions on immobilized strategy through vacancy inducing, manipulating coordination configuration, and dynamic evolution mechanism of single-atom level catalytic site in photocatalytic water splitting.