Ag-TiO2 mesocrystal-coupled g-C3N4 nanosheets with enhanced visible-light photocatalytic activity

In order to increase the photocatalytic performance of titanium dioxide mesocrystals (TMCs), in this study, Ag nanoparticles with different mass content were first photodeposited on the surface of as-prepared TMCs to form heterostructured Ag-TMCs catalysts, followed by loading them on g-C3N4 via one step bottom-to-up calcination method. The results of photocatalytic degradation toward RhB experiments showed that the prepared ternary photocatalyst of g-C3N4/Ag-TMCs exhibited excellent photocatalytic activity not only compared with the bare TMCs and Ag-TMCs, but also with all of those reported TiO2/Ag/g-C3N4 ternary photocatalysts. Such improved photocatalytic properties were attributed to the synergistic effect created by the LSPR effect and an important role as an electron-conduction bridge of Ag and the existence of heterojunction structure formed between Ag, TMCs and the further coupling g-C3N4, which added to the evidences that enabled the prepared g-C3N4/Ag-TMCs catalyst enhanced transfer efficiency of photogenerated carriers and suppressed recombination rate of electron-hole pairs. Moreover, the deposited Ag content had a positive effect on the photocatalytic degradation efficiency. On the basis of the results of this study, the specimen of g-C3N4/9% Ag-TMCs showed RhB degradation efficiency up to 100% under only 15 min visible-light irradiation. A possible degradation mechanism was also proposed based on several characterizations including photoluminescence spectrum and a serious of photoelectrochemical measurements. Overall, the prepared g-C3N4/Ag-TMCs ternary photocatalyst with good recyclability looked promising for future practical applications in the visible-light photodegradation of organic pollutants.

Automated summary

In this study, a ternary photocatalyst of g-C3N4/Ag-TMCs was prepared by photodepositing Ag nanoparticles on the surface of titanium dioxide mesocrystals followed by loading them on g-C3N4. The prepared photocatalyst exhibited excellent photocatalytic activity and the deposited Ag content positively influenced the photocatalytic degradation efficiency. The improved photocatalytic properties were attributed to the synergistic effect created by the LSPR effect of Ag, electron-conduction bridge role of Ag, and the heterojunction structure formed between Ag, TMCs, and g-C3N4.