MOF derived highly dispersed bimetallic Fe-Ni nitrogen-doped carbon for enhanced peroxymonosulfate activation and tetracycline degradation

Abstract

Transition metals as activators of peroxymonosulfate (PMS) are effective catalysts for the degradation of organic pollutants. The construction of multiple active sites is the key for enhanced PMS activation. Herein, we prepared ZIF-8 derived Fe- Ni nitrogen-carbon with highly dispersed bimetallic active sites, achieving a small amount of highly efficient catalytic performance for tetracycline (TC) degradation. The Fe and Ni elements in the catalyst were uniformly dispersed, resulting in a high specific surface area of 367 m2/g. Even at low metal concentrations (Fe=0.83%, Ni=0.33%), Fe-Ni-N-C/PMS showed superior performance in degrading total carbon TC. Its reaction rate constant was 1.71 times higher than Fe-N-C/PMS and 2.13 times higher than Ni-N-C/PMS. This significant improvement was attributed to the synergistic effect of the bimetallic components and the highly dispersed active sites. The mechanism was proposed that Fe-Ni-N-C activates PMS to generate hydroxyl radicals (•OH), sulfate radicals (SO4•−), superoxide radicals (O2•−), and singlet oxygen (1O2) to further degrade TC. Among them, 1O2 and SO4•−were the main reactive oxygen species. This work has provided a new insight into the development of transition metals with multiple active sites for the degradation of organic pollutants.