3D chrysanthemum-like g-C₃N₄/TiO₂ as an efficient visible-light-driven Z-scheme hybrid photocatalyst for tetracycline degradation

Utilization of a solar-driven semiconductor as a photocatalyst to degrade antibiotic pollutants is a feasible and environmentally friendly technology. In this paper, 3D chrysanthemum-like g-C₃N₄/TiO₂ as a visible-light-driven hybrid photocatalyst with a Z-scheme heterostructure was firstly synthesized by the in situ hydrothermal synthesis method. Experiments proved that this 3D chrysanthemum-like g-C₃N₄/TiO₂ had better degradation performance toward tetracycline than TiO₂ and g-C₃N₄. In particular, when optimized g-C₃N₄/TiO₂-2 was applied for tetracycline removal (200 ml, 10 mg L⁻¹), the corresponding degradation efficiency could reach nearly 100% within 60 min. The improved photocatalytic activity was the result of better utilization of the heterostructure-induced visible light, more efficient charge transfer in the Z-scheme heterojunction as well as stronger redox capability. The Z-scheme degradation mechanism was supported by the trapping experiments of active species and ESR radical detection, and the whole photocatalytic process was controlled by the combined action of ˙O₂⁻, h⁺ and ˙OH radicals. This study may be beneficial for the design of more efficient sunlight-driven hybrid photocatalysts and their applications in wastewater treatment.