Nano-sized g-C3N4 thin layer @ CeO2 sphere core-shell photocatalyst combined with H2O2 to degrade doxycycline in water under visible light irradiation

In this work, g-C3N4 thin layer @ CeO2 core-shell composite photocatalyst was synthesized by simple hydro thermal and in situ synthesis method for the first time, and it was combined with hydrogen peroxide (H2O2) to degrade the antibiotic doxycycline hydrochloride (DOX) under visible light. A series of techniques were employed to characterize the as-synthesized materials. XRD patterns indicated that the samples were successfully synthesized. SEM and TEM images displayed the core-shell microstructure of the as-synthesized composite. The surface element composition and the valence states of the samples were characterized by XPS. The optical properties of the materials were determined by DRS and FTIR. The results of FTIR and XPS indicated that strong interactions between g-C3N4 and CeO2 had formed during the synthesis process. Photodegradation experiments showed that the addition of H2O2 can greatly enhance the photocatalytic degradation rate of DOX. Active species trapping experiments and ESR experiments demonstrated that superoxide radicals, hydroxyl radicals and holes (O-center dot(2)-, (OH)-O-center dot and h(+)) played major roles in the photocatalytic process. Finally, a possible degradation mechanism was proposed. This work has synthesized a new core-shell structure system for g-C3N4 and CeO2 composite photocatalyst and provides a solution for the purification of pharmaceutical wastewater.