Multiple catalytic reaction sites induced non-radical/radical pathway with graphene layers encapsulated Fe-N-C toward highly efficient peroxymonosulfate (PMS) activation

Abstract

Understanding the origin of high activity of graphene layers encapsulated Fe-N-C catalysts in Fenton-like reaction is critical, but still challenging for developing catalysts with high activity and durability. Therefore, we prepared a highly active Fe-N-C catalyst (FexMny-Fe@NCs) containing FeN4 coordination to activate peroxymonosulfate (PMS) toward 4-aminobenzoic acid ethyl ester (ABEE) degradation, and revealed the multiple catalytic reaction sites by investigating the composition and the structure of the catalyst. The relationship between the catalytic degradation performance and multiple catalytic reaction sites was performed on the basis of both experiments and density functional theory (DFT) calculations. The catalytic performance of Fe2Mn1-Fe@NCs was found to show optimal catalytic degradation performance. Pyrrolic N served as adsorption site as well as singlet oxygen generation site to promote the catalytic degradation. Fe-pyridinic N-C acted as hydroxyl radical and sulfate radical generation site. Both singlet oxygen and superoxide radical were dominated the catalytic reaction. The insight achieved from this study may be further applied to other Fe-N-C catalysts design and further efficient organic pollution remediation.