Solvothermally grown ZnO/BiOCl photocatalyst for solar-light-responsive degradation of tetracycline antibiotic

Binary photocatalyst based on ZnO/BiOCl was constructed very easily using a solvothermal route by addition of solid ZnO to the reaction mixture during the formation of BiOCl. The two-component heterojunction was then applied for sunlight-active removal of tetracycline (TC) drug. The synthesized heterostructure showed mainly the characteristic XRD peaks of BiOCl with the band gap of 3.50 eV, compared to 3.30 eV of the bare BiOCl. The binary photocatalyst comprising 0.05 g of ZnO per 1.0 g of BiOCl (denoted as 0.05ZnO/BiOCl) displayed the lowest photoluminescence signal, compared to the synthesized BiOCl and ZnO. This indicates the greatest carrier separation rate at the interface detected in the binary ZnO/BiOCl, compared to other photocatalysts. The result corelates well with the maximum photoactivity detected in the 0.05ZnO/BiOCl. High photocatalytic performance of 100% was detected under 100 min of UV light (135 W, a mercury lamp). In addition, 98% removal of TC under natural sunlight was also achieved within 240 min. The photodegradation of TC agrees perfectly with the first-order kinetic model providing a rate constant of 0.0546 min^–1. This is about 1.9 times higher than those obtained from either ZnO or BiOCl photocatalysts. The binary ZnO/BiOCl heterostructure still exhibits the promising photodegradation efficiency after five runs. The scavenger experiment reveals that the photogenerated electrons are the major species which play a crucial role in TC degradation. This work emphasizes a facile route to fabricate the two-component heterostructure, with promising performance, for removal of TC antibiotic in natural water.