CuO with (0 0 1)-plane exposure efficiently induces peroxymonosulfate to form ≡Cu-OOSO₃^-intermediates directly oxidizing organic contaminants in water

Copper (Cu)/peroxymonosulfate (PMS) is a complex coupling system due to its multiple activation pathways with the formation of diverse radical and nonradical species. However, the effects of CuO with different plane exposures on the properties of the coupling system are not clear. In this research, Cu atom-terminated (0 0 1) plane-exposed CuO (CuO-10) is synthesized by a facile hydrothermal method using NH₃·H₂O as the structure directing agent for the first time. CuO-10 has the excellent property of inducing PMS to degrade bisphenol A (BPA) in water, and its reaction rate constant (k) reaches 14 times higher than that of commercial CuO with exposed (0 1 0) plane terminated by O atoms (CuO-C). Meanwhile, CuO-10 exhibits a wide pH_initial adaptability, and its BPA degradation exceeds 87% in the pH range of 3–9. Furthermore, compared with CuO-C/PMS, less radical and ¹O₂ are found in CuO-10/PMS oxidation system. Compared to the UV/PMS system, organic contaminants in CuO/PMS systems are easier to oxidize via an oxygen-atom-transfer mechanism. Therefore, the ≡Cu(II)-OOSO₃^- metastable intermediate is speculated to play an important role in the CuO/PMS activation process, which oxidizes organic contaminants directly through oxygen-atom-transfer and single-electron-transfer pathways. Furthermore, the CuO-10/PMS system is more likely to degrade organic pollutants through the oxygen-atom-transfer pathway than the CuO-C/PMS system. This study not only explores the influence of CuO crystal planes in efficiently inducing PMS activation but also provides new insights into the PMS activation process in the CuO/PMS oxidation system.