Mesoporous structure and amorphous Fe-N sites regulation in Fe-g-C3N4 for boosted visible-light-driven photo-Fenton reaction

• Published in: Journal of colloid and interface science 2022-02, Vol.608, p.2515-2528
• Main Authors: Ding, Chenjie, Kang, Shifei, Li, Wenxin, Gao, Weikang, Zhang, Zhihao, Zheng, Lulu, Cui, Lifeng
• Format: Article
• Language: English
• Subjects: Fe-N active sites; Ferrikinetics; Green synthesis; Mesoporous Fe-g-C3N4; Photo-Fenton system
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2021.10.168

[Display omitted] •FeC2O4··2H2O was used as both iron source and pore-forming agent in the synthesis of melamine derived g-C3N4.•Fe-g-C3N4 photo-Fenton catalysts with ideal mesoporous structure and hyperdispersed immobilized iron species was successfully achieved.•XPS and EDS mapping results indicating a good Fe-Nx covalent structure, thus boost the charge separation and photo-Fenton performance.•This work provides a sustainable route to develop mesoporous catalysts with ideal metal-N active sites. Heterogeneous photo-Fenton catalysts prepared by doping metal ions in g-C3N4 are promising alternatives to traditional homogeneous Fenton catalysts, but are restricted by poor mesoporous structure and agglomerate of metal species. Recently, the highly uniformly dispersed metal-N active sites in various photocatalysts have been proved to be the critical reason for their enhanced catalytic activity. In this study based on reasonable control of mesoporous structure and metal-N active sites, mesoporous Fe-g-C3N4 was synthesized using a simple one-step thermal shrinkage polymerization method using ferrous oxalate as iron source and pore-forming agent. The Fe and N elements in the triazine ring skeleton of Fe-g-C3N4 form a σ-π bond, thus the photogenerated electrons can be quickly transferred to Fe3+ to form Fe2+ under the interaction of chemical bonds, accelerating the Fenton reaction rate. Density functional theory calculations results demonstrate that the energy band structure and electron cloud density distribution of Fe-Nx active structure are better than that of routine FeOx crystal structure with metal species agglomeration. In addition, the excellent mesoporous structure of Fe-g-C3N4 creates conditions for the high exposure of Fe-Nx active sites in the photo-Fenton reaction under visible light. The as-developed Fe-g-C3N4 system shows high recyclability and excellent photo-Fenton performance for removal of typical intractable pollutants (The degradation rate of dye and tetracycline reaches 98.2% and 98.7% at 60 and 120 min, respectively). This work provides a facile and sustainable route to develop mesoporous highly-active heterogeneous Fenton-like catalysts and even further general the design of general catalyst with ideal metal-N active sites, thereby promoting a feasible and efficient wastewater remediation solution.