Rationally designed hierarchical hollow CuS/CdIn2S4 heterostructure nanoboxes for boosted photoreduction of CO2†

A novel double-shelled CuS/CdIn₂S₄ photocatalyst was rationally designed using CdIn₂S₄ sheets in situ grown upon the exterior of hollow CuS nanocubes. The unique hierarchical hollow structure of CuS/CdIn₂S₄ provides numerous active sites and reduces carrier diffusion length. Surface sulfur vacancies mitigate the detachment of the intermediate, which is favorable for a multi-electron reaction path such as that in the production of CH₄. Meanwhile, a suitable band-structure alignment between p-type CuS and n-type CdIn₂S₄ leads to the formation of a type-II heterostructure, thus resulting in effective light-harvesting and spatial separation of electron–hole pairs for CO₂ photoreduction. The CuS/CdIn₂S₄ heterostructure exhibits significantly enhanced performance with a boosted CO yield of 40.73 μmol g⁻¹ h⁻¹ as well as a noticeably improved CH₄ selectivity (36.5%, 23.41 μmol g⁻¹ h⁻¹). This work introduces innovative concepts in designing photocatalytic systems with unique morphologies and rational band structures, promising advancements in CO₂ photoreduction at reduced costs.