Manipulating the Selective Generation of Hydroxyl Radicals by Nitrogen-Doped Carbon Catalysts for Efficient Fenton-Like Reactions

Abstract

Hydroxyl radical (^•OH)-dominated Fenton-like reactions offer a promising strategy for the degradation of refractory organic pollutants. However, the application of nitrogen-doped carbon (NC) catalysts for ^•OH generation is hindered by the loss of active nitrogen species during high-temperature synthesis (900–1200 °C), and an effective strategy to promote the homolytic cleavage of hydrogen peroxide (H₂O₂) remains necessary. Herein, an NC catalyst with abundant active nitrogen for enhanced ^•OH generation was prepared from zeolitic imidazolate frameworks by low-temperature pyrolysis at 800 °C, followed by acid-washing. Theoretical calculations and experimental results demonstrated that pyridinic and pyrrolic N significantly enhance the homolytic cleavage of H₂O₂, leading to selective and efficient generation of ^•OH, while graphitic N favors the less effective heterolytic cleavage pathway. Building on this finding, the active N species were precisely regulated by adjusting the pyrolysis temperature, resulting in the optimized NC-800 catalyst achieving 91.13% total organic carbon removal for extracting wastewater from spent lithium-ion battery recycling. Moreover, the activity of NC-800 was restored after simple thermal treatment, demonstrating excellent regeneration capability. This study sheds light on strengthening the pathways of NC catalysts through manipulating nitrogen species and provides an efficient approach for wastewater treatment.