How metal/support interaction improved degradation performance in the peroxymonosulfate activation process: significance of high-valent cobalt-oxo species

Abstract

Currently, the strategy of metal loading is expected to promote the nonradical catalytic activity of transition metal spinel oxide catalysts in peroxymonosulfate (PMS) systems, but the connection between the mechanism of degradation performance improvement and metal–support interaction (MSI) remains unclear. Herein, a novel CoFe₂O₄ loaded sepiolite composite (10-CFS) was prepared for PMS activation to degrade ciprofloxacin (CIP). 10-CFS exhibited outstanding PMS activation ability, and 98.7% of CIP was degraded within 30 min, which was significantly higher than that of the physical mixture of sepiolite and CoFe₂O₄ (59.8%). A series of experiments demonstrated that the presence of Co(IV)O caused the better degradation performance of 10-CFS. Notably, theoretical calculations signified that MSI not only promoted the coupled electron–proton transfer (CEPT) process and thus changed the formation pathway of Co(IV)O, but also facilitated PMS adsorption on 10-CFS and lowered the energy barrier for Co(IV)O generation. In summary, this study illustrates deeply the mechanism of catalytic performance improvement after metal loading by focusing on the MSI and bridges the gap in understanding the MSI and degradation performance.