Synergistic reduction of U(VI) and selective oxidation of benzyl alcohol to prepare benzaldehyde via WOx/g-C3N4

In the photoreduction of U(VI), protective gases and additional sacrificial agents are still the major obstacles. Herein, we developed an oxygen-deficient WOx/g-C3N4 catalyst for the simultaneous reduction of U(VI) and preparation of benzaldehyde by selective oxidation of benzyl alcohol without protective gases and sacrificial agents. The removal of U(VI) by WOx/g-C3N4 could reach 98.5% and the conversion of benzyl alcohol was nearly 32% with a selectivity close to 100%. Compared with single g-C3N4 and defect-free WO3, the photoreduction activity of WOx/g-C3N4 was 10.4 and 7 times higher, respectively. Besides, the role of oxygen and oxygen defects was explored. Owing to oxygen defects in the catalyst, oxygen was adsorbed on the oxidation end (WOx) of the catalyst and activated without entering the reduction end to interfere with the photoreduction of U(VI), while favoring the generation of •O2- to improve the selectivity of benzaldehyde. Finally, a new mechanism was proposed.