Visible Light Driven Spherical CuBi2O4 with Surface Oxygen Vacancy Enhanced Photocatalytic Activity: Catalyst Fabrication, Performance, and Reaction Mechanism

Here, a spherical CuBi2O4 catalyst with surface oxygen vacancy was fabricated through a facile hydrothermal method, which exhibited remarkable enhanced photocatalytic activity of refractory chemicals in the heterogeneous sulfate radical-based Fenton-like reaction under visible light emitting diode (LED) light irradiation. The property of the catalysts was systematically characterized by scanning electron microscopy (SEM)/high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV/vis methods. The effects of parameters of solution pH, potassium peroxymonosulfate (PMS) concentration, catalyst dosage, and catalyst reusability on Rhodamine B (RhB) degradation were investigated. In the interface reaction, the improved photodegradation efficiency could be attributed to the decomposition of PMS, which produced sulfate radicals and hydroxyl radicals owing to the transmission of photo-generated electron/hole pairs. Herein, the introduction of surface oxygen vacancy as well as the cycling of copper valence states (Cu(II)/Cu(I) pairs) can facilitate the production of free reactive radicals, leading to the high degradation efficiency. The catalyst showed high removal efficiency and presented good cycle stability in the reaction. Additionally, the free radical quencher experiment and electron spin resonance (EPR) experiments were conducted, and a proposed photocatalytic mechanism was also illustrated.