Metal-organic framework-derived hollow Co3O4/carbon as efficient catalyst for peroxymonosulfate activation

Concurrently rational optimization and design of the structure and composition of catalysts are significant for improving its catalytic performance. In this report, a novel hollow carbon supported ultrafine Co3O4 nano-particles (HCo3O4/C) with a diameter of 6-12 nm were prepared as an active catalyst for peroxymonosulfate (PMS) activation. Initially, the zeolitic-imidazole-framework (ZIF-67) was synthesized followed by top-down etching strategy to get the hollow structure. Finally, as prepared hollow ZIF-67 was used as a precursor to fabricate HCo3O4/C. To understand the effects of structure and final composition on catalytic performance, another material, solid carbon supported Co3O4 nanoparticles (SCo3O4/C) was synthesized for comparison. The catalytic efficiency in control experiments between HCo3O4/C and SCo3O4/C was identified; in which HCo3O4/C demonstrated more than two times improved catalytic efficiency as compared to a solid structure. Interestingly, the HCo3O4/C catalyst exhibits better efficiency for PMS activation to generate sulfate radicals (SO4-center dot ) and the results show that degradation rate of targeted pollutant bisphenol A (BPA) was achieved up to 97% in 4 min, which is higher than other reported catalysts. The other factors which could influence PMS activation were also analyzed as well, for instance, the solution pH, catalyst loading, pollutant (BPA) concentration, system tem-perature and effect of organic molecules. Moreover, the Liquid chromatography-mass spectrometry (LC-MS) was used to identify the BPA degraded intermediate products. This work provides a new prospect into the synthesis of high-performance metal-organic framework (MOF) derived catalysts with exceptional properties, which may encourage the employ of hollow MOF materials in more practical applications.