TiO2/C coated Co3O4 nanocages for peroxymonosulfate activation towards efficient degradation of organic pollutants

Developing new catalysts for efficient degradation of micropollutants in water is of significant importance in advanced oxidation processes (AOPs). Herein, TiO2/C coated Co3O4 nanocages (Co3O4@TiO2/C) were synthesized and their performance on micropollutants degradation was evaluated. Specifically, cobalt-based Zeolitic imidazolate framework (ZIF-67) coated by a thin layer of titanium species and polydopamine (PDA) was used as a precursor for the preparation of Co3O4@TiO2/C by two-step calcination. The catalytic performance of peroxymonosulfate (PMS) activation towards the degradation of organic pollutants was investigated by using atrazine (ATZ) and Bisphenol A (BPA) as typical micropollutants. The efficiency and the effect of TiO2/C shell on the as-synthesized catalyst were analyzed by comparing Co3O4 derived from ZIF-67 and Co3O4/C derived from ZIF-67/PDA. ATZ degradation results showed that the Co3O4@TiO2/C catalyst was the most efficient for catalytic oxidation when 99.5% of ATZ was removed within 4 min, which is 57.5% and 74.6% faster than that of Co3O4@C and Co3O4, respectively. The enhanced performance of Co3O4@TiO2/C is attributed to their unique nanocages structure and improved specific surface area. The catalysis mechanisms and ATZ degradation pathways were presented based on the results of electron paramagnetic resonance (EPR), XPS, and LC-MS analysis. Our results might have added to the design of heterogeneous catalysts of large surface area for efficient PMS activation in AOPs.