Modulation of the structures and properties of iron-carbon composites by different small molecular carbon sources for Fenton-like reactions

Abstract

In this study, different types of small molecular carbon sources such as melamine, dicyandiamine, pyrocatechol, and o-phenylenediamine were used to regulate the surface structures of iron/nitrogen/carbon-based composites (Fe-N/C), which were used to activate peroxymonosulfate (PMS). The relationship between different small molecular carbon sources and the electronic structure was investigated. The characteristics of metal-carrier interaction in the Fe-N/C were clarified. As a result, there were significant differences in the degradation efficiency of catalysts prepared with different small molecular carbon sources, which was related to the types of active sites. Density functional theory (DFT) and experiments results showed that the catalyst rich in CO-C and FeN_x exhibited better catalytic activity, which may be attributed to the higher adsorption energy for PMS. The main active species for catalytic degradation of ofloxacin were identified as sulfate radical (SO₄^•-) and hydroxyl radical (^•OH) by electron paramagnetic resonance (EPR) spectra. The introduction of different small molecular carbon sources can significantly affect the distribution and electronic structure of active sites on the catalyst surface, thereby regulating the generation and migration of radicals.