Constructing a 3D ordered macroporous cobalt monoatomic catalyst for efficient SMX degradation via PMS activation

The cobalt monoatomic catalyst with 3D ordered macropores structure (3DOM Co/NC) was prepared using the crystalline porous material ZIF-67 and SiO 2 as the precursor and template, and used to investigate the effect of its activation with peroxymonosulfate (PMS) on sulfamethoxazole (SMX) removal. The mesoporous structure mostly retained after ZIF-67 carbonisation, and the formation of new homogeneous macropores after the removal of the SiO 2 template, which greatly increases the surface area of the catalyst (429 m 2 g −1 ) and promotes long-range mass transfer. Additionally, Co monoatomic sites were formed in the porous skeleton, providing electrons that were utilised for the activation of PMS. This distinctive structure enables it to almost completely degrade of 20 ppm SMX within 3 min and show excellent catalytic degradation efficiency in a wide pH range (3.0–9.0) and high-salinity simulated wastewater (10–100 mM). In addition, the main ROS in the catalytic degradation process were explored as 1 O 2 and O •2- . Combined with the results of DFT calculations and product analyses, the active sites of SMX were predicted and the degradation pathways and mechanisms were inferred, confirming that the degradation process of SMX poses a low risk of toxicity to the environment. This study reveals that the addition of 3DOM Co/NC was more favourable for the activation of PMS for SMX degradation, which contributes to the development and improvement of advanced oxidation processes for environmental remediation.