Novel AgI/BiOBr/reduced graphene oxide Z-scheme photocatalytic system for efficient degradation of tetracycline

A novel AgI/BiOBr/reduced graphene oxide (RGO) composite was prepared through a facile solvothermal method followed by an in-situ precipitation process. The as-prepared AgI/BiOBr/RGO ternary composite exhibited significantly enhanced photocatalytic activity towards the degradation of tetracycline (TC) under simulated sunlight irradiation. The degradation rate of AgI/BiOBr/RGO was approximately 5.9 and 2.9 times higher than that of pristine BiOBr and AgI, respectively. The improved photocatalytic activity of AgI/BiOBr/RGO composite could be ascribed to the synergistic effect of AgI, BiOBr and RGO. The RGO/BiOBr nanosheets could provide aboundant reactive active sites and serve as appropriate substrates for in-situ growth of AgI NPs. Furthermore, RGO with superior electronic conductivity accelerated the separation of photogenerated electron-hole pairs in AgI/BiOBr/RGO composite, as well as extended visible-light absorption capability. The possible degradation pathway of TC was proposed through the identification of intermediate products using LC-MS analysis. Additionally, combined with the results of active species trapping experiments and ESR measurements, a possible mechanism of RGO-promoted Z-scheme charge transfer for AgI/BiOBr/RGO composite was proposed.