Enhanced peroxymonosulfate activation via MOF-derived bimetal core-shell Co-Fe@NC hybrids to degrade emerging pollutants

Abstract

The reasonable control of the structure of metal–organic frameworks (MOFs) is a promising strategy for improving their peroxymonosulfate (PMS) activation activity. In this study, ZIF-67 @ZIF-8 was used as a template to prepare bimetallic core–shell Co-Fe@NC via Fe doping and high-temperature carbonization. Co-Fe@NC maintained the core–shell structure of the original MOF, in which cobalt was uniformly distributed in the nitrogen-doped graphite carbon skeleton and the surface of the graphite carbon skeleton was covered with iron. With the synergistic effect of the nitrogen-doped graphite carbon skeleton, iron, and cobalt, 100% of tetrabromobisphenol S (TBBPS) was removed in 60 min with kobs = 0.062 min−1 in Co-Fe@NC-0.2/PMS system. The addition of iron increased the graphitization degree with ID/IG value increased from 0.98 (Co@NC) to 1.034 (Co-Fe@NC-0.2) and electron transfer rate of the carbon skeleton. Besides, the Co leaching was effectively attenuated from 1.86 mg/L(Co@NC) to 0.78 mg/L (Co-Fe@NC-0.2) by the core-shell structure and bimetal strategy. Both O2·- and 1O2 contributed to the degradation of TBBPS according to quenching experiments. TBBPS was deeply degraded into small-molecule compounds through three degradation pathways by the Co-Fe@NC-0.2/PMS system. This study provides a new strategy for designing highly efficient bimetal–carbon composites for environmental remediation.