CoZn-ZIF and melamine co-derived double carbon layer matrix supported highly dispersed and exposed Co nanoparticles for efficient degradation of sulfamethoxazole

Metal-organic framework (MOF)-derived carbon materials have drawn tremendous attention as activators of peroxymonosulfate (PMS) for the degradation of antibiotics. However, it is still challenging to construct MOF-derived materials with well-dispersed and highly-exposed metal active sites. Herein, the bimetallic Cobalt-Zinc-zeolite imidazolate framework and melamine co-derived double layer nitrogen-doped porous carbon matrix supported highly dispersed cobalt nanoparticles (Co NPs) (denoted as Co-NC-C) with the exposure of more Co NPs sites was developed by one-step pyrolysis method. The transmission electron microscopy results demonstrate that double layer carbon matrix as a dispersant can effectively inhibit the agglomeration of Co NPs, and Co-NC-C possessed more exposure of Co active sites compared with Co-NC without melamine. Co-NC-C efficiently activated PMS to remove over 96.67% of sulfamethoxazole (SMX) at a widespread range of pH within 120 min due to its the highly-exposed Co active sites and high graphitization degree. Additionally, the degradation mechanism dominated by the singlet oxygen was demonstrated. Finally, four products and two probable degradation pathways of SMX were confirmed. Half of the products were less toxic than SMX based on the ecological structure activity relationships analysis results. The study provides valuable insights for the development of MOF-derived catalysts with well-dispersed and highly-exposed metal active sites.