Shihui Zhang,Xu Zhang,Wanting Shi,Weiyan He,Caihong Li,Xiaojing Wang
Slow charge transfer and a weak built-in electric field (BIEF) at the heterojunction interface critically hinder the construction of efficient S-scheme heterojunctions. Secondary calcination and ultrasonic treatment of g-C 3 N 4 enhance interfacial contact with MIL-101, shortening carrier migration paths. P and Mn doping increases the Fermi-level difference between g-C 3 N 4(C,S) and MIL-101, strengthening the BIEF to drive directional carrier migration. This facilitates the recombination of carriers with low-redox-potential at the heterojunction interface while spatially separating carriers with high-redox-potential, successfully constructing an S-scheme P-Mn-MCN (C,S) heterojunction. The optimized system delivers remarkable photocatalytic performance, achieving 98 % tetracycline hydrochloride degradation under visible light within 60 min.
Ternary g-C 3 N 4 /Ti 3 C 2 T x /MIL-101(Fe) photocatalyst was constructed via in situ assembly. • Ti 3 C 2 T x promotes interfacial charge separation and accelerates electron transfer. • Rapid in situ H 2 O 2 generation enables an oxidant-free visible-light photo-Fenton process. • CTF achieves efficient, broad-spectrum degradation of dyes and PPCPs. Visible-light photo-Fenton oxidation represents a promising strategy for removing dyes and pharmaceuticals/personal care products (PPCPs), which are persistent water contaminants. However, its broader application is constrained by challenges such as inefficient charge separation and dependence on externally added hydrogen peroxide (H 2 O 2 ). In this study, a ternary g-C 3 N 4 /Ti 3 C 2 T x /MIL-101(Fe) photocatalyst was synthesized via the in-situ growth of MIL-101(Fe) on g-C 3 N 4 /Ti 3 C 2 T x , enabling efficient visible-light-driven, zero-external H 2 O 2 -added photo-Fenton degradation of organic pollutants. The hybrid system exhibits significantly enhanced oxygen activation and interfacial electron-transfer capability, with in situ H 2 O 2 generation rates about three times higher than those of pristine g-C 3 N 4 . Under visible-light irradiation, the composite continuously produces reactive oxygen species ( ∙ O 2 - , and ∙ OH) at substantially higher levels than g-C 3 N 4 and g-C 3 N 4 /MIL-101(Fe), indicating promoted charge separation and faster interfacial electron transfer. As a result, the catalyst enables broad-spectrum pollutant removal within 60 min, achieving degradation efficiencies of 99.78% (methylene blue), 99.49% (rhodamine B), 88.27% (tribromophenol), 61.50% (doxycycline hydrochloride), and 78.98% (levofloxacin). Overall, rapid in situ H 2 O 2 formation, coupled with efficient ROS generation, enables high-performance pollutant degradation without the need for external oxidant dosing, providing a green strategy for degrading dyes and PPCPs under visible light. Download: Download high-res image (174KB) Download: Download full-size image A ternary g-C 3 N 4 /Ti 3 C 2 T x /MIL-101(Fe) photocatalyst enables visible-light-driven, oxidant-free photo-Fenton degradation of dyes and PPCPs through MXene-promoted charge separation and rapid in situ H 2 O 2 generation. The self-generated H 2 O 2 activates Fe 3+ /Fe 2+ cycling to continuously produce h + , ∙O 2 - , and ∙OH, achieving efficient pollutant mineralization.
The residues of oxytetracycline hydrochloride (OTC) in water have potential adverse effects on human health and ecological environment. Photocatalytic degradation has been widely studied in the treatment of antibiotic pollution due to its environmentally friendly and efficient characteristics. However, the band gap of traditional photocatalysts is too wide, and the recombination of photogenerated electrons and holes is serious, which has negative effects on photocatalysis . Therefore, the Z-scheme heterojunction g-C 3 N 4 @MIL-101(Fe) composite photocatalyst was synthesized by high temperature calcination combined with solvothermal method. g-C 3 N 4 @MIL-101(Fe) was characterized by XRD, FTIR , SEM, TEM and other tests. All the results showed that the compound was successful A series of photoelectric tests showed that g-C 3 N 4 @MIL-101(Fe) has a narrower band gap, stronger light absorption ability, and improved the separation rate of photogenerated electrons and holes. Under visible light irradiation, g-C 3 N 4 @MIL-101(Fe) could remove 87.68% of OTC in 300 min. g-C 3 N 4 @MIL-101(Fe) showed good potential for practical application in five real water samples and stability after six cycles. Finally, superoxide radicals and hole radicals were identified as the main reactive species in the photodegradation process. The mechanism and pathway of the photocatalytic degradation of OTC by g-C 3 N 4 @MIL-101(Fe) are proposed. This work expands the construction and application of Fe-MOF based Z-scheme heterostructure and provides a new idea for water pollution remediation.
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