CNTs with nano-confined TiO2 and surface loading Co3O4: The analysis of its performance and mechanism of PMS activation for ECs degradation under visible light

The efficient activation of peroxymonosulfate for degrading emerging contaminants has become a focal point in recent decades, emphasizing the development of novel materials and efficient strategies for high-performance degradation. This study explores a spatial confinement strategy, where TiO2 is confined inside carbon nanotubes with Co3O4 loading outside, is performed to prepare the nano-confined composite TiO2-in-CNT/Co3O4. Norfloxacin is chosen as the primary target pollutant, revealing a degradation rate exceeding 97 % within 30 min. The non-radical 1O2 species were confirmed to be generated in nano-confined catalyst, but not observed in the control non-confined catalyst. Additionally, the quantity of original radical active species significantly increases in nano-confined catalyst compared to non-confined catalyst. TiO2-in-CNT/Co3O4 has excellent reusability and application universality. Wonderful stability is observed in real water and anti-ion interference experiments, highlighting its robust stability. Experimental and DFT calculation results also demonstrate that the spatial confinement strategy prevents nanoparticle aggregation, accelerates electron transfer efficiency, and promotes the cycling of Co2+/Co3+ electron pairs. This work provides insights into the regulation of confined effects in activating PMS and offers a feasible strategy for the synergistic activation of PMS for water environment remediation through a radical and non-radical mixed mechanism.