Enhanced degradation of micropollutants over iron-based electro-Fenton catalyst: Cobalt as an electron modulator in mesochannels and mechanism insight

Xiaoqian Chen; Wei Teng; Jianwei Fan; Yanyan Chen; Qian Ma; Yinghao Xue; Chuning Zhang; Wei-Xian Zhang

doi:10.1016/j.jhazmat.2021.127896

Enhanced degradation of micropollutants over iron-based electro-Fenton catalyst: Cobalt as an electron modulator in mesochannels and mechanism insight

J Hazard Mater. 2022 Apr 5:427:127896. doi: 10.1016/j.jhazmat.2021.127896. Epub 2021 Nov 26.

Authors

Xiaoqian Chen¹, Wei Teng², Jianwei Fan¹, Yanyan Chen¹, Qian Ma¹, Yinghao Xue¹, Chuning Zhang¹, Wei-Xian Zhang¹

Affiliations

¹ State Key Laboratory for Pollution Control, College of Environmental Science and Engineering, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai 200092, PR China.
² State Key Laboratory for Pollution Control, College of Environmental Science and Engineering, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai 200092, PR China. Electronic address: wteng@tongji.edu.cn.

PMID: 34862103
DOI: 10.1016/j.jhazmat.2021.127896

Abstract

Heterogeneous electro-Fenton (hetero-EF) process is an emerging alternative for effective oxidation of recalcitrant micropollutants, but it is hampered by limited hydroxyl radical (•OH) generation and low stability on the iron-based cathodes. Herein, we demonstrate an enhanced hetero-EF performance via modulation of iron electronic structure in an ordered mesoporous carbon (OMC). By tuning the cobalt incorporation, the highly-dispersed iron-cobalt (FeCo) nanoalloys in mesochannels (Fe_0.5Co_0.5@OMC) show a 3-fold increase in •OH yield compared with Fe@OMC, achieving degradation efficiency with 92% of sulfamethazine (SMT) and 99% of rhodamine B (RhB), and the corresponding total organic carbon (TOC) removal with 66% of SMT and 85% of RhB within 2 h in neutral pH, respectively. Experimental results and density functional theory (DFT) calculations demonstrate that iron incorporated with cobalt reduces energy barrier for facile generation of H₂O₂ and •OH from O₂ through direct electron transfer, along with decreased overpotential. Meanwhile, cobalt doping promotes H₂O₂ decomposition by accelerated Fe(II)/Fe(III) cycle and Co(II)/Co(III) redox. Furthermore, spatially confined and half-embedded structure endows the nanocatalyst (8 nm) excellent durability within a wide pH value range and good stability in cycle tests. A plausible reaction mechanism and degradation pathway for SMT are proposed. Moreover, the superiority of Fe_0.5Co_0.5@OMC cathode is maintained in simulated wastewater, suggesting an enormous potential in practical wastewater treatment.

Keywords: Electrocatalytic degradation; Hydroxyl radicals; Iron-based materials; Mesoporous carbon; Micropollutants.