Hierarchical assembly of highly efficient visible-light-driven Ag/g-C3N4/kaolinite composite photocatalyst for the degradation of ibuprofen

A novel Ag/g-C3N4/kaolinite composite photocatalyst was fabricated for the first time through a two-step assembly strategy by employing in situ calcination and a photodeposition process. The synthesized Ag/g-C3N4/kaolinite composite reached a higher degradation rate of ibuprofen (IBP) with a reaction rate constant of 0.0113 min−1 at an Ag content of 7% under visible-light irradiation, which was approximately 1.87 times that of the Ag/g-C3N4 composite. Based on the physicochemical properties, the enhanced photocatalytic activity was attributed to the stronger adsorption property, wider photoresponse range and more efficient separation and transfer of electron-hole pairs. Furthermore, the incorporation of monodispersed Ag nanoparticles onto the g-C3N4/kaolinite sheets provided more reactive sites for the IBP degradation. In addition, according to the EPR study and trapping experiments, it was demonstrated that holes (h+) should be the key reactive species. A possible pathway of IBP degradation was also proposed based on the detected intermediates. Overall, the results of this work may facilitate the design of a novel visible-light-driven photocatalyst with a high efficiency that is derived from a natural mineral for environmental remediation.