Ultrathin ZnIn₂ S₄ Nanosheets Anchored on Ti₃ C₂ T_X MXene for Photocatalytic H₂ Evolution

Photocatalysts derived from semiconductor heterojunctions that harvest solar energy and catalyze reactions still suffer from low solar-to-hydrogen conversion efficiency. Now, MXene (Ti₃ C₂ T_X ) nanosheets (MNs) are used to support the in situ growth of ultrathin ZnIn₂ S₄ nanosheets (UZNs), producing sandwich-like hierarchical heterostructures (UZNs-MNs-UZNs) for efficient photocatalytic H₂ evolution. Opportune lateral epitaxy of UZNs on the surface of MNs improves specific surface area, pore diameter, and hydrophilicity of the resulting materials, all of which could be beneficial to the photocatalytic activity. Owing to the Schottky junction and ultrathin 2D structures of UZNs and MNs, the heterostructures could effectively suppress photoexcited electron-hole recombination and boost photoexcited charge transfer and separation. The heterostructure photocatalyst exhibits improved photocatalytic H₂ evolution performance (6.6 times higher than pristine ZnIn₂ S₄ ) and excellent stability.