Remarkable 4 Nitrophenol Degradation and Mineralization Performance Using Simple-Fabricated Oxygen Vacancy-Rich Copper Oxide/Peroxymonosulfate Photocatalytic System

Inducing intrinsic oxygen vacancies (V_O) through structural engineering, rather than relying on complex doping or heterostructure formation, represents a novel and simplified strategy in developing high-efficiency catalyst. In this work, we report a facile and scalable chemical precipitation route to synthesize copper (II) oxide (CuO) nanorods (NRs) characterized by an unprecedented density of V_O defects. These NRs serve as an extraordinary activator for peroxymonosulfate (PMS) in a sulfate () radical-based advanced oxidation process (AOP). The CuO-PMS synergy achieved significant degradation of 10 ppm of 4-nitrophenol (4NP), reaching 84.47% degradation and 88.11% total organic carbon (TOC) mineralization within 5 min. With only small doses of 0.1 g/L CuO and 0.65 mM PMS, the system further achieved 95.36% degradation and 91.39% mineralization of the same sample. This high performance is attributed to the synergy of lower crystallinity, higher surface area, and greater V_O defects presence in the NRs compared to bulk CuO. The system operated effectively under normal to low-alkaline pH conditions, exhibiting a high capacity to oxidize higher 4NP doses, demonstrating excellent reusability, and a wide applicability range for various pollutants. Singlet oxygen () has been identified as the main driver of the oxidation process, as confirmed by scavenger tests. This study provides a pivotal blueprint for the design of defect-rich binary metal oxides, offering a pragmatic yet powerful solution for high-performance wastewater remediation.