In Situ Construction of the van Der Waals Heterojunction Based on Co3O4/g-C3N4 for the Highly Efficient Degradation of Tetracycline under Visible Light

Advanced oxidation processes have been increasingly applied to degrade organic pollutants through the generation of strong oxidizing radicals by catalyst activation reactions. In this study, the Co₃O₄/g-C₃N₄ van der Waals heterojunction (CCN) was successfully prepared by calcining a mixture of Co₃O₄ and g-C₃N₄ (BCN) in order to improve the performance and elucidate the mechanism of the CCN-activated peroxymonosulfate (PMS) catalytic degradation of tetracycline (TC) under visible light. This unique nanostructure possesses an abundance of active sites, thus significantly facilitating the transport of charge. The TC removal rate of the optimized heterojunction reaches 300.1 × 10^-3 min^-1 within 10 min under visible light, nearly 46.2 times that of BCN. The degradation of TC was dominated by h⁺ and ¹O₂. The degradation pathways of TC were analyzed in detail. The reduced toxicity of the intermediates reveals the potential risk to the environment posed by the CCN-3/PMS system. Finally, a preliminary economic analysis of this process was carried out. The study provides a simple and promising route for the efficient activation of PMS by CCN for photocatalytic remediation of water pollution.