In-situ phase reconstruction of MnOOH/δ-MnO2 steering interfacial electronic regulation to boost electron transfer process for water purification.

Developing non-radical peroxymonosulfate (PMS) activation pathways that resist interference from complex water matrices remains challenging for the treatment of emerging contaminants in practical applications. A polyvinyl pyrrolidone-assisted hydrothermal strategy was therefore developed to induce the partial in-situ reconstruction of δ-MnO2 into MnOOH. The resulting MnOOH/δ-MnO2 interface directed PMS activation toward an electron transfer process (ETP) for tetracycline (TC) removal. The catalyst achieved nearly complete TC removal within 30 min and maintained high activity under complex water matrix conditions. Experimental results and density functional theory (DFT) analysis revealed that the MnOOH/δ-MnO2 composite interface strengthened PMS adsorption and promoted interfacial charge redistribution. These effects facilitated electron transfer during TC oxidation. Surface-bound PMS* species on the MnOOH/δ-MnO2 interface acted as electron-accepting centers, steering TC oxidation toward an ETP-dominated non-radical pathway. The MnOOH/δ-MnO2 catalytic membrane maintained above 98% TC removal in real water matrices under continuous-flow conditions at only 0.2 mM PMS. These results demonstrate the promising practical applicability of the system. Life cycle assessment further indicated a comparatively low environmental burden for the MnOOH/δ-MnO2/PMS system. These findings provide a mechanistic basis for designing manganese oxide/oxyhydroxide catalysts through polymer-induced interfacial reconstruction and offer a practical strategy for ETP-dominated PMS activation in complex water treatment.