Synergistic Photocatalytic Oxidation and Reductive Activation of Peroxymonosulfate by Bi-Based Heterojunction for Highly Efficient Organic Pollutant Degradation

Organic pollutants present a substantial risk to both ecological systems and human well-being. Activation of peroxymonosulfate (PMS) have emerged as an effective strategy for the degradation of organic pollutants. Bi-based heterojunction is commonly used as a photocatalyst for reductively activating PMS, but single-component Bi-based heterojunction frequently underperforms due to its restricted absorption spectrum and rapid combination of photogenerated electron–hole pairs. Herein, BiVO4 was selected as the oxidative semiconductor to form an S-type heterojunction with CuBi2O4—x-CuBi2O4/BiVO4 (x = 0.2, 0.5, and 0.8) for PMS photoactivation. The built-in electric field (BEF) in x-CuBi2O4/BiVO4 promoted electron transfer to effectively activate PMS. The x-CuBi2O4/BiVO4 heterojunctions also demonstrate stronger adsorption of the polar PMS than pure CuBi2O4 or BiVO4. In addition, the BEF prompts photoelectrons able to reduce O2 to •O2− and photogenerated holes in the valence band of BiVO4 able to oxidize H2O to generate •OH. Therefore, under visible light irradiation, 95.1% of ciprofloxacin (CIP) can be degraded. The 0.5-CuBi2O4/BiVO4 demonstrated the best degradation efficiency and excellent stability in cyclic tests, as well as a broad applicability in degrading other common pollutants. The present work demonstrates the high-efficiency S-type heterojunctions in the coupled photocatalytic and PMS activation technology.