Fabrication of heterostructured CdS/TiO2 nanotube arrays composites for photoreduction of U(VI) under visible light

Highlights: • Heterostructured CdS/TiO₂ nanotube arrays composites were successfully synthesized. • The CdS nanoparticles were only anchored on the inner wall of TNTAs instead of blocking the tubes. • TNTAs shell can effectively prevent photocorrosion of CdS. • CdS/TNTAs exhibited excellent photocatalytic reduction activity towards U(VI). Heterostructured CdS/TiO₂ nanotube arrays composites (CdS/TNTAs) were synthesized by the successive ionic layer adsorption (SILAR) reaction with vacuum freeze-drying-assisted method. The CdS nanoparticles were anchored on the inner wall of the anodic TNTAs via strong electronic interaction rather than occupied the nanotubes. The CdS/TNTAs-10 with 27.28wt% CdS exhibited shows the best photocatalytic activity for reduction of U(VI) (97% at 240min) and the photocatalytic activity was still 83.6% after 5 cycles. These improvements probably stem from the porous tubular structure of TNTAs acts as the protective shell which can effectively inhibit the photocorrosion of CdS and promote the photoinduced interfacial electron-hole pairs separation. Furthermore, the possible the photocatalytic electron transfer path was proposed, and the photogenerated electrons (e^-) and the superoxide radicals (·O₂^-) were the predominant active free radicals. This work highlighted a simple synthesis of CdS/TNTAs heterojunction with potential application in radioactive wastewater remediation.