The microthermal construction of Z-scheme CdS@g-C3N4 composite: Efficient tetracycline photodegradation, reaction mechanism and possible degradation pathway

Abstract

The heterojunction structure with CdS@g-C3N4 photocatalyst was obtained via a simple microthermal chemical in-situ deposition method. The catalyst CdS@g-C3N4 (weight ratio of 1:3) maintained excellent degradation activity to 10 ppm tetracycline (TC) after four cycles due to Z-scheme electron transport mechanism, which was demonstrated through several methods, and the photo-corrosion of CdS was inhibited successfully own to this electron transfer paths. Microscope images showed CdS nanoparticles were uniformly distributed on g-C3N4 nanosheets, such surface morphology provided numerous active sites and excellent adsorption performance for photodegradation process. Mechanism study demonstrated the high energy active species including h+, •O2− and •OH take part in the degradation process. Through the mass spectrometry analysis, intermediate products and degradation pathway were inferred on TC during photodegradation process. In addition, this study proved the extremely low toxicity of TC aqueous solution after degradation, there was special significance for ecological and environmental protection. This work provided a reference for the design of the Z-scheme photocatalyst and synthesis of catalysts at low temperature (80 °C), and it has application potential in the treatment of water pollution.