Visible light-induced catalytic performance of composite photocatalyst synthesized with nanomaterials WO3 and two-dimensional ultrathin g-C3N4

To improve the visible light-induced catalytic activities of Ultrathin g-C₃N₄ (UCN), a promising photocatalyst WO₃/UCN (WU) was synthesized. Its visible light-driven photocatalysis performance was controllable by adjusting the theoretical mass ratio of WO₃/UCN. We have calibrated the optimal preparation conditions to be: WO₃/UCN ratio as 1:1, the stirring time of the UCN and sodium tungstate mixture as 9 h and the volume of concentrated hydrochloric acid as 6 mL which was poured into the mixture solution with an extra stirring time of 1.5 h. The optimal photocatalyst WU_opt had porous and wrinkled configurations. Its light absorption edge was 524 nm while that of UCN was 465 nm. The band gap of WU_opt was 2.13 eV, 0.3 eV less than that of UCN. Therefore, the recombination rate of photo-generated electron-hole pairs of WU_opt reduced significantly. The removal rate of WU_opt on RhB was 97.3%. By contrast, the removal rate of UCN was much lower (53.4%). WU_opt retained a high RhB removal rate, it was 5.5% lower than the initial one after being reused for five cycles. The photodegradation mechanism was facilitated through the strong oxidation behaviors from the active free radicals ·O₂^-, ·OH and h⁺ generated by WUopt under the visible light irradiation.