Yolk-shell ZIFs@SiO2 and its derived carbon composite as robust catalyst for peroxymonosulfate activation

Cobalt-based Zeolitic imidazolate frameworks (ZIFs) have shown a great potential for radical production by activating peroxymonosulfate (PMS). However, improve the stability of ZIFs in the reaction remains a significant challenge. In this work, ZIF-67 was synthesized and protected by coating with a layer of silica, furthermore, the yolk-shell ZIFs@SiO2 was carbonized under inner gas to obtain the Co containing carbon. When the above samples were applied for catalytic degradation of Rhodamine B (RhB) in the presence of PMS, both of them shows similar performance, with higher RhB removal efficiency and stability than that of pure ZIF-67. Additionally, factors affecting the PMS activation such as catalyst and PMS dosage and solution pH were also investigated. Radical quenching tests and electron paramagnetic resonance (EPR) revealed that 1O2 was the dominant active species involving in the degradation process. Finally, the reusability of the catalysts was studied and the spent catalysts were analyzed. Overall, the results provide insights into synthesis of yolk-shell ZIFs@SiO2 catalyst with enhanced performance for the degradation of organic pollutants from effluent.