Construction of Hierarchical Hollow Co₉ S₈ /ZnIn₂ S₄ Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

Visible-light-responsive hierarchical Co₉ S₈ /ZnIn₂ S₄ tubular heterostructures are fabricated by growing 2D ZnIn₂ S₄ nanosheets on 1D hollow Co₉ S₈ nanotubes. This design combines two photoresponsive sulfide semiconductors in a stable heterojunction with a hierarchical hollow tubular structure, improving visible-light absorption, yielding a large surface area, exposing sufficient catalytically active sites, and promoting the separation and migration of photogenerated charges. The hierarchical nanotubes exhibit excellent photocatalytic H₂ evolution and Cr^VI reduction efficiency. Under visible-light illumination, the optimized Co₉ S₈ /ZnIn₂ S₄ heterostructure provides a remarkable H₂ generation rate of 9039 μmol h^-1 g^-1 without the use of any co-catalysts and Cr^VI is completely reduced in 45 min. The Co₉ S₈ /ZnIn₂ S₄ heterostructure is stable after multiple photocatalytic cycles.