Oxygen vacancy chemical environment regulation of Mn-Fe dual-site efficient activation of peroxymonosulfate degradation of phenol

MnFe-O activates PMS to remove 99.34% phenol within 30 min. • Oxygen vacancies regulate Mn-Fe dual-site electronic coupling. • MnFe-O shows higher Fe 2+ and Mn 3+ contents for rapid redox cycling. • O 2 •− / 1 O 2 -coupled pathways dominate phenol oxidation in MnFe-O/PMS. • MnFe-O/PMS maintains high activity in diverse real water matrices. Peroxymonosulfate (PMS) activation technology has significant application potential in the removal of phenolic pollutants, but its catalytic performance is still limited by problems such as insufficient regulation of the electronic structure of active sites and unclear interfacial reaction pathways. This study used MnFe Prussian blue analogue (MnFe-PBA) as a precursor to construct a series of MnFe-X (X = O, S, Se) catalysts through thermal conversion and oxygen vacancy-related defect engineering, and systematically compared the effects of different vacancy types on the PMS-activated degradation performance of phenol. The results showed that the MnFe-O sample, which was jointly regulated by oxygen vacancy-related defects and structural reconstruction, exhibited the best catalytic activity, achieving 99.34% phenol removal within 30 min, with an apparent rate constant as high as 0.20 min −1 , which was significantly better than the MnFe-PBA and S/Se vacancy-regulated samples. XPS analysis showed that the increased proportions of Fe 2+ (77.25%) and Mn 3+ (70.00%) in MnFe-O created a more favorable local electronic environment for electron coupling and redox cycles. EPR and quenching results indicate that •OH, SO 4 •− , O 2 •− and 1 O 2 are generated simultaneously in the system, and an oxidation pathway dominated by O 2 •− / 1 O 2 coupling is ultimately formed. This work reveals the key role of oxygen vacancy-related defects and structural reconstruction in jointly regulating the activation of PMS by Mn-Fe dual sites, providing a new mechanistic basis for defect engineering-driven bimetallic catalyst design and efficient purification of phenolic wastewater. Download: Download high-res image (230KB) Download: Download full-size image