Facile construction of novel Bi2WO6/Ta3N5 Z-scheme heterojunction nanofibers for efficient degradation of harmful pharmaceutical pollutants

Pharmaceutical wastewater has become a severe, tremendous threaten to ecological environment and human health. Semiconductor photocatalysts have emerged as potential candidates for degrading pharmaceutical pollutants. Construction of highly efficient, stable and recyclable Z-scheme photocatalysts that are superior to individual constituents or widely studied heterojunction photocatalysts is very fascinating yet challenging. Herein, we report an efficient, stable and recyclable visible-light-driven (VLD) Bi2WO6/Ta3N5 Z-scheme heterojunction with compact interface contact fabricated via an electrospinning-calcination-solvothermal route, in which abundant Bi2WO6 nanosheets are in-situ, compactly and vertically grown on the surface of the Ta3N5 nanofibers. These as-fabricated Z-scheme Bi2WO6/Ta3N5 heterojunctions display dramatically enhanced VLD catalytic activity compared to pristine Bi2WO6, Ta3N5, or the mixture of Bi2WO6 and Ta3N5. Particularly, Bi2WO6/Ta3N5 (1.0Bi-Ta) presents the highest photocatalytic property for the removal of tetracycline hydrochloride (TC) and ciprofloxacin (CIP), achieving approximately 86.7% and 81.1% degradation efficiency, respectively. The extraordinary photocatalytic property is ascribed to the Z-scheme hetero-structure with unique core-shell architecture that realizes compactly interfacial contact between the components for efficient separation of photoexcited carriers, strong visible-light absorption, as well as possesses the strong oxidation ability of photo-excited hole, and the high reduction capacity of photo-excited electron. The trapping experiments combined with electron spin resonance (ESR) analyses verify the prevailing role of photo-induced holes (h(+)), superoxide radicals (center dot O2-), and hydroxyl radicals (center dot OH) in the Bi2WO6/Ta3N5 photocatalytic system. Notably, the direct contact between Bi2WO6/Ta3N5 and contaminants is experimentally demonstrated to be significant for the efficient degradation of pollutants. Moreover, Bi2WO6/Ta3N5 is endowed with easily recyclable characteristics and excellent durability. Therefore, this research illustrates that Bi2WO6/Ta3N5 may hold a great prospect for the treatment of harmful pharmaceutical pollutants.