Formation of Hierarchical FeCoS₂–CoS₂ Double-Shelled Nanotubes with Enhanced Performance for Photocatalytic Reduction of CO₂

Hierarchical FeCoS₂–CoS₂ double-shelled nanotubes have been rationally designed and constructed for efficient photocatalytic CO₂ reduction under visible light. The synthetic strategy, engaging the two-step cation-exchange reactions, precisely integrates two metal sulfides into a double-shelled tubular heterostructure with both of the shells assembled from ultrathin two-dimensional (2D) nanosheets. Benefiting from the distinctive structure and composition, the FeCoS₂–CoS₂ hybrid can reduce bulk-to-surface diffusion length of photoexcited charge carriers to facilitate their separation. Furthermore, this hybrid structure can expose abundant active sites for enhancing CO₂ adsorption and surface-dependent redox reactions, and harvest incident solar irradiation more efficiently by light scattering in the complex interior. As a result, these hierarchical FeCoS₂–CoS₂ double-shelled nanotubes exhibit superior activity and high stability for photosensitized deoxygenative CO₂ reduction, affording a high CO-generating rate of 28.1 μmol h⁻¹ (per 0.5 mg of catalyst). © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim