High-dispersed single-atom Fe on N-doped biochar for efficient degradation of organic contaminants by activating peroxymonosulfate

The Fe-N-C catalyst was synthesized using loofah sponge-derived carbon and applied for peroxymonosulfate (PMS) activation to degrade organic pollutants. The catalyst, featuring highly dispersed single-atom Fe on the N-C framework, showed outstanding activity for phenol degradation across a wide pH range. The incorporation of Fe significantly boosted the catalytic performance, achieving rapid degradation of phenol at 20 mg L⁻¹ within 10 min, using 0.5 mmol L^‒1 of PMS and 0.2 g L⁻¹ of catalyst. Electron paramagnetic resonance (EPR) and reactive oxygen quenching experiments identified the singlet oxygen (¹O₂) and superoxide radical (O₂^•‒) as the main reactive oxygen species, with the former playing a key role. It has been demonstrated that the Fe-N_x structures were the active sites that facilitated the generation of ¹O₂, thereby enhancing the catalytic activity of the Fe-N-C materials. The catalyst also effectively addressed pollutants like Rhodamine B and climbazole, indicating its potential for environmental remediation. The synthesis approach for Fe-N-C is applicable to other transition metals, such as Mn, Co, Ni, Cu, and Zn, providing valuable insights for the development of highly efficient and durable M-N-C catalysts.