Synergistically enhanced photocatalytic degradation of tetracycline hydrochloride by Z-scheme heterojunction MT-BiVO4 microsphere/P-doped g-C3N4 nanosheet composite

The elimination of tetracycline hydrochloride (TC-HCl) from water has attracted extensive research attention. This study hydrothermally synthesized composite photocatalysts composed of BiVO4 microspheres containing coexisting phases of monoclinic scheelite (M-BiVO4) and tetragonal zircon (T-BiVO4), i.e., MT-BiVO4, loaded onto P-doped g-C3N4 nanosheets (PCNS). Furthermore, their morphology, structure, and photoelectrochemical properties were comprehensively characterized, and the performance and stability of photocatalytic degradation of TC-HCl were examined. Additionally, the effects of humic acid (HA), coexisting anions/cations, and actual water samples on the degradation efficiency of TC-HCl were investigated, and the degradation mechanism and pathways were examined. The findings indicated that the percentage of M-BiVO4 in MT-BiVO4 considerably influences the photocatalytic activity of the composite catalyst. Furthermore, the excellent photocatalytic performance of 5% BVO/PCNS was attributed to the synergistic effects of P-doping the modified g-C3N4, MT-BiVO4 isotype heterojunction effects, and the Z-scheme heterojunction constructed from MT-BiVO4 and PCNS, which can enhance the absorption range of the visible light and accelerate the transfer and separation of charge carriers between catalysts. The free radical capture experiments and electron spin resonance tests indicated that holes and O2- were the dominant active species in the photocatalytic degradation process. With high reusability and stability, the 5% BVO/PCNS composite has great potential for practical wastewater treatment applications. This study offers a new approach for preparing photocatalysts synergized by isotype and Z-scheme heterojunctions.