Double-shelled hollow nanosphere assembled by TiO2@surface sulfate functionalized CdS for boosting photocatalysis reduction of U(VI) under seawater conditions

Photocatalytic technology could efficiently treat U(VI) from aqueous and simulated seawater conditions, which is critical for the sustainable development of nuclear energy. Herein, TiO2@surface sulfate functionalized CdS double-shell hollow nanosphere (TiO2@[SO4]/CdS-x) was constructed and applied for photocatalysis reduction of U(VI). The introduction of [SO4]/CdS could facilitate separation and transfer of photogenerated electron-hole, and accelerate U(VI) diffusion to promote photocatalytic reactions kinetics. Accordingly, the TiO2@[SO4]/CdS-2 (the mass ratio of 16.8%) could completely remove U(VI) illuminated for 10 min in 3 mmol·L−1 of NaHCO3 and maintain 88% after five cycles, and the apparent rate constant is 59 and 16.5 times as much as TiO2 hollowspheres and [SO4]/CdS. Additionally, the electron transfer at TiO2@[SO4]/CdS-2 interface conforms to Z-type conduction mechanism that promotes the photogenerated electrons collected on [SO4]/CdS surface, cooperating with superoxide radicals to reduce U(VI) to α-U3O8. These results indicate the great application of double-shell hollow nanospheres photocatalysts for uranium recovery from seawater.