Construction of cerium oxide nanoparticles immobilized on the surface of zinc vanadate nanoflowers for accelerated photocatalytic degradation of tetracycline under visible light irradiation

Abstract

Construction of Z-scheme heterojunction has been deemed to be an effective and promising approach to boost the photocatalytic activity on account of accelerating the separation efficiency of the photogenerated carriers and maintaining the strong redox ability. Herein, an attractive CeO2/Zn3V2O8 Z-scheme heterojunction photocatalyst was rationally constructed by zero-dimensional (0D) CeO2 nanoparticles immobilized on the surface of three-dimensional (3D) Zn3V2O8 nanoflowers using a simple mixing method, and applied to the photocatalytic degradation of tetracycline (TC) under visible light irradiation. As expected, it was observed that the prepared CeO2/Zn3V2O8 hybrid illustrated significantly boosted the photocatalytic activity for the elimination of TC compared to pure Zn3V2O8. More importantly, the optimized CeO2(40 wt%)/Zn3V2O8 hybrid owned the largest elimination rate of TC with 1.13 × 10−2 min−1, which was around 8.1 and 3.8 times as high as single CeO2 (0.14 × 10−2 min−1) and Zn3V2O8 (0.30 × 10−2 min−1), respectively. The appreciable performance improvement was mainly ascribed to the formation of Z-scheme heterojunction between CeO2 and Zn3V2O8, facilitating the transfer rate of photogenerated carriers and remaining the high reducibility of photoexcited electrons in CeO2 and strong oxidizability of photoinduced holes in Zn3V2O8. Active species capture experiments and electron spin resonance spectra showed that superoxide radicals and holes were the main active species for TC degradation. Besides, the possible degradation pathways of TC were speculated by identifying degradation intermediates, and the reasonable degradation mechanism including migration and transport behaviors of charge carriers and generation processes of reactive species were revealed in depth. This investigation enriches Zn3V2O8-based Z-scheme heterojunction photocatalytic system and offers a new inspiration for the construction and fabrication of high-efficiency Z-scheme heterojunction photocatalysts to remove the antibiotics from wastewater.