Nitrogen-Doped Carbon Anchoring Zero-Valent Cobalt Driving a Multi-path Catalytic Ozonation Mechanism Mediated by Surface Atomic Oxygen

Abstract

The practical application of heterogeneous catalytic ozonation is hindered by active site deactivation, metal leaching, and unclear interfacial mechanisms. Herein, we propose a sustainable catalyst (Co/ACON700) with highly dispersed zero-valent cobalt (ZVCo) anchored on a nitrogen-doped carbon support. By regulating the pyrolysis temperature, an electron-rich microenvironment is created, which stabilizes ZVCo via metal–support interactions (cobalt leaching < 0.78%) and accelerates interfacial electron transfer. When applied to the catalytic ozonation of phenol, Co/ACON700 achieves a turnover frequency (TOF) of 0.65 min–1 and a total organic carbon (TOC) removal of 94.1% and improves the ozone utilization efficiency by 34.91%. Mechanistic investigations unveil a ZVCo-mediated multi-path ozone activation mechanism, where ZVCo acts as an electron donor to directly reduce ozone, undergoing in situ oxidation to generate Co2+, accompanied by the formation of surface atomic oxygen (*O). This process triggers a multi-path oxidation regime in which interfacial hydroxyl radicals (·OHint) and singlet oxygen (1O2) play important roles. The catalyst shows good cycling stability, anti-interference in complex water matrices, and effective performance in actual coking wastewater treatment. Life cycle assessment (LCA) indicates its lower environmental impact, highlighting practical engineering potential. This work provides a green strategy for designing high-performance, low-leaching, durable ozone catalysts.