Preparation of flower-like Co3O4 QDs/Bi2WO6 p-n heterojunction photocatalyst and its degradation mechanism of efficient visible-light-driven photocatalytic tetracycline antibiotics

A novel flower-like Co3O4 QDs/Bi2WO6 p-n heterostructure photocatalyst was prepared by hydrothermal and ultrasonic synthesis strategies with uniformly dispersing zero-dimensional (0D) Co3O4 QDs on the three-dimensional (3D) flower-like Bi2WO6 nanosheets. The structural morphology and optical properties analysis confirmed the successful combination of the Co3O4 QDs/Bi2WO6 composite photocatalyst. Photodegradation experiments results proved that 10%-Co3O4 QDs/Bi2WO6 showed the optimum rate constant (0.017 min−1) for the degradation of TC, which was about 3.40 and 1.55 times higher than Co3O4 QDs (0.005 min−1) and Bi2WO6 (0.011 min−1), respectively. The significant improvement in the photocatalytic performance of Co3O4 QDs/Bi2WO6 was mainly attributed to the enhancement of visible light absorption capacity and the formation of p-n heterojunction, which effectively inhibited the recombination of electron/holes (e-/h+) pairs. Radical trapping experiments and electron spin resonance (ESR) spectrum demonstrated that O2– radicals were the leading active species in photocatalytic degradation. Furthermore, three-dimensional excitation-emission matrix fluorescence spectra (3D EEMs) and Liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/Q-TOF MS) techniques results revealed the degradation pathway and mechanism of efficient visible-light-driven photocatalytic tetracycline antibiotics. The outstanding photocatalytic performance makes the 0D/3D Co3O4 QDs/Bi2WO6 p-n heterojunction photocatalyst a promising photocatalyst for the degradation of tetracycline antibiotics.