Hollow Co3O4 Nanoreactors for Selective Catalytic Oxidation of Emerging Contaminants via Electron-Transfer-Mediated Peroxydisulfate Activation

Abstract

The selective removal of electron-rich emerging organic contaminants (EOCs) from aquatic environments remains a critical challenge, as conventional radical-based oxidation processes suffer from poor selectivity and interference from background constituents. To address this issue, we report an electron-transfer-mediated catalytic oxidation system using peroxydisulfate (PDS) activated by hollow multi-shelled Co3O4 (HoMS Co3O4) nanoreactors derived from plant-based tannic acid. The triple-shelled hollow architecture affords a high specific surface area with abundant accessible active sites, enabling the HoMS Co3O4/PDS system to achieve complete bisphenol A (BPA, 0.04 mM) removal within 90 min (k = 0.045 min−1). Mechanistic investigations, integrating electron paramagnetic resonance spectroscopy, radical quenching, electrochemical analyses and in situ Raman/FTIR spectroscopy, reveal that the degradation proceeds via an electron-transfer-mediated non-radical pathway, in which surface-complexed PDS serves as the primary reactive species. This pathway enables selective oxidation of electron-rich pollutants and endows the system with broad pH adaptability, strong resistance to coexisting water constituents, and robust performance in real water matrices (>93% BPA removal). Moreover, the system maintains stable operation in a continuous flow-through reactor over 72 h with negligible Co2+ leaching, offering a sustainable strategy for the selective remediation of EOC-contaminated waters.