Direct electrospinning preparation of Z-scheme mixed-crystal Bi2O3/g-C3N4 composite photocatalysts with enhanced visible-light photocatalytic activity

A novel Z-scheme mixed-crystal Bi2O3/g-C3N4 composite photocatalyst was successfully prepared by a simple electrospinning-calcination approach. The micromorphology, configuration, chemical interaction and optical properties of the synthesized composite photocatalyst were analyzed and the photocatalytic degradation efficiency was estimated by the photodegradation of antibiotics. The results show that Bi2O3 nanofibers existing as alpha and beta mixed-crystal phases are prepared and mixed with g-C3N4 nanosheets, thus forming a highly efficient alpha-Bi2O3/beta-Bi2O3/g-C3N4 homoheterojunction. Transfer of the photogenerated electrons and holes in the fabricated alpha-Bi2O3/beta-Bi2O3/g-C3N4 homoheterojunction follows a Z-scheme enhanced photocatalytic mechanism, resulting in the effective separation and transfer of photogenerated e(-) and h(+). Moreover, the mixed-crystal Bi2O3/g-C3N4 photocatalyst has an enhanced visible-light absorbance. Therefore, the Bi2O3/g-C3N4 composite displays high photocatalytic properties for degrading tetracycline hydrochloride under 5 W LED visible-light irradiation, and the high photocatalytic activity is maintained even after 5 cycles, indicating the outstanding stability and reusability of the composite photocatalyst.