Noncovalent hybridization of Fe single-atom with biochar for highly efficient peroxymonosulfate activation: Built-in electric field-driven radical and non-radical processes

A non-covalent hybridisation method was used to manipulate the electron transfer from BC to an iron monoatomic catalyst (SA Fe-N-C) using biochar (BC) as a dopant. By optimizing the mass proportion of BC to SA Fe-N-C during co-pyrolysis, the stack structure of two componants was successfully fabricated. The built-in electric field (BIEF) is induced by the defect position of graphite carbon structure in BC and the electron-withdrawing nitrogen atom in SA Fe-N-C. The electron transport road from BC to SA Fe-N-C was established by using the BIEF between the interfaces. As a result, the non-covalent stack of BC/SA Fe-N-C rendered a promising way in activating peroxymonosulfate (PMS), and meanwhile exhibited superior stability concerning their robust geometric skeleton. The degradation experiments showed that the degradation efficiency of the composite was increased to 91% compared with that of the pristine SA Fe-N-C (69%) at a extremely higher concentration of TC (20 mg/L). Based on theoretical calculations and in-situ detections, it was found that the PMS activation follows the route of generating radicals (SO4•–,•OH) and non-radical (1O2, Fe(V)=O). The presence of the BIEF accelerated the electron delocalization, driving the electrons transfer for Fe(III)/Fe(II) and Fe(V)=O/Fe(III) recycle. The present study offer a new pathway for the synergistic PMS activation by combing single atom catalysts and biochar.