Eco-Friendly Lignin-Based N/C Cocatalysts for Ultrafast Cyclic Fenton-Like Reactions in Water Purification via Graphitic N-Mediated Interfacial Electron Transfer

Abstract

Herein, an eco-friendly lignin-based N-doped cocatalyst (N/C) was fabricated to enhance Fenton-like oxidation capacity. The N/C-assisted Fe(III)/H2O2 system showed ultrafast pollutant oxidation activity via an accelerated Fe(III)/Fe(II) cycle, exhibiting 16.9 times better caffeine removal efficiency than equivalent quantities of the classical Fenton system. N/C cocatalysts exhibited extraordinary stability and generality in the decontamination and disinfection of complex solution matrixes. Both experimental and theoretical calculation results demonstrated that graphitic N was the active site on N/C cocatalysts, which could elevate the reactivity of Fe(III) and make the interfacial electron transfer more feasible. In the N/C-mediated Fe(III)/H2O2 system, an increase in electron transfer on the surface of N/C facilitated the formation of surface-bound Fe(II), thereby activating H2O2 to produce hydroxyl radicals, the main active species for contaminant degradation. Notably, practical continuous water purification could be achieved by assembling N/C into fixed-bed reactors or membrane treatment units. These findings provide novel insights into N-doped carbonaceous cocatalysts and a promising green strategy for practical water treatment.