Oxygen vacancies (O_v) on metal oxide surfaces exhibit high catalytic activity for activating peroxymonosulfate (PMS) in wastewater decontamination, yet their in-situ regeneration remains a significant challenge. This study successfully achieves in-situ real-time regeneration of O_v on CuO surfaces through simple alkali etching without interrupting the contaminant removal process. The surface hydroxyl groups introduced by alkali treatment significantly reduce the formation energy of O_v on CuO surfaces from 1.60 eV to 0.38 eV. Both experimental results and density functional theory calculations reveal that the high activity of CuO relies on the synergy of surface hydroxyl groups and O_v. This synergy increases the antibonding states below the Fermi level and the electron spin density of Cu near O_v, thereby promoting electron transfer from CuO to PMS. As a result, by just adding an equimolar amount of alkali relative to PMS in CuO/PMS system, the degradation rate constant of sulfamethoxazole (SMX) greatly increases by 42 times. The primary reactive oxygen species in this system are sulfate radicals and hydroxyl radicals. Furthermore, OH^-/CuO/PMS system exhibits a long-term stability (> 300 h) for SMX removal in a real water matrix. This work provides a highly executable method to in-situ real-time regenerate O_v on CuO surfaces, representing significant progress in the critical yet underappreciated field of catalyst regeneration.

The development of high-efficient and low-cost oxygen reduction reaction (ORR) electrocatalysts is crucial for the practical applications of metal-air batteries. One promising way is to develop Fe single-atom catalysts. However, the single active center and inherent electronic structure of Fe single-atom catalysts lead to the undesirable adsorption of multiple ORR intermediates. Herein, a charge-asymmetry single-atom alloy (SAA) catalyst with Fe–Cu dual sites supported on nitrogen-doped carbon nanosheet (Fe₁Cu SAA/NC) was constructed. Various characterizations manifest the existence of electron interaction between Fe and Cu in Fe₁Cu SAA/NC, which facilitates the adsorption of ORR intermediate for fast kinetics. Consequently, the charge-asymmetry Fe₁Cu SAA/NC exhibits much faster ORR kinetics with a half-wave potential of 0.917 V vs. reversible hydrogen electrode (RHE), outperforming its counterparts in the references. Furthermore, Fe₁Cu SAA/NC still maintains a high half-wave potential with only a drop of 5 mV after 5000 cycles, indicating excellent stability. This work provides a new strategy to design highly active and non-noble metal ORR electrocatalysts, which hold great potential for various catalytic applications.