Oxygen-containing functional groups in Fe3O4@three-dimensional graphene nanocomposites for enhancing H2O2 production and orientation to 1O2 in electro-Fenton

Yi Chen; Ruidian Su; Fei Xu; Mengyu Ma; Yan Wang; Defang Ma; Qian Li

doi:10.1016/j.jhazmat.2024.134162

Oxygen-containing functional groups in Fe₃O₄@three-dimensional graphene nanocomposites for enhancing H₂O₂ production and orientation to ¹O₂ in electro-Fenton

J Hazard Mater. 2024 May 15:470:134162. doi: 10.1016/j.jhazmat.2024.134162. Epub 2024 Mar 29.

Authors

Yi Chen¹, Ruidian Su¹, Fei Xu², Mengyu Ma¹, Yan Wang¹, Defang Ma¹, Qian Li³

Affiliations

¹ Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao 266200, PR China.
² Environment Research Institute, Shandong University, Qingdao 266200, PR China.
³ Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, Shandong Key Laboratory of Environmental Processes and Health, School of Environmental Science and Engineering, Shandong University, Qingdao 266200, PR China. Electronic address: qianli@sdu.edu.cn.

PMID: 38555670
DOI: 10.1016/j.jhazmat.2024.134162

Abstract

In electro-Fenton (EF), development of a bifunctional electrocatalyst to realize simultaneous H₂O₂ generation and activation efficiently for generating reactive species remains a challenge. In particular, a nonradical-mediated EF is more favorable for actual wastewater remediation, and deserves more attention. In this study, three-dimensional graphene loaded with Fe₃O₄ nanoparticles (Fe₃O₄@3D-GNs) with abundant oxygen-containing functional groups (OFGs) was synchronously synthesized using a NaCl-template method and served as a cathode to establish a highly efficient and selective EF process for contaminant degradation. The amounts of OFGs can be effectively modulated via the pyrolysis temperature to regulate the 2e^- oxygen reduction reaction activity and reactive oxygen species (ROS) production. The optimized Fe₃O₄@3D-GNs synthesized at 750 °C (Fe₃O₄@3D-GNs-750) with the highest -C-O-C and -C꞊O group ratios exhibited the maximum H₂O₂ and ¹O₂ yields during electrocatalysis, thus showing remarkable versatility for eliminating organic contaminants from surface water bodies. Experiments and theoretical calculations have demonstrated the dominant role of -C-O-C in generating H₂O₂ and the positive influence of -C꞊O sites on the production of ¹O₂. Moreover, the surface-bound Fe(II) favors the generation of surface-bound •OH, which steers a more favorable oxidative conversion of H₂O₂ to ¹O₂. Fe₃O₄@3D-GNs were proven to be less pH-dependent, low-energy, stable, and recyclable for practical applications in wastewater purification. This study provides an innovative strategy to engineer active sites to achieve the selective electrocatalysis for eliminating pollution and reveals a novel perspective for ¹O₂-generation mechanism in the Fenton reaction.

Keywords: Electro-Fenton; Fe(3)O(4)@3D graphene nanocomposites; H(2)O(2) production; Oxygen-containing functional groups; Singlet oxygen.