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Construction of g-C3N4/PDI@MOF heterojunctions for the highly efficient visible light-driven degradation of pharmaceutical and phenolic micropollutants
Summary:
The authors from Soochow University and National Center for International Research on Intelligent Nano-Materials and Detection Technologies in Environment Protection developed a g-C3N4/PDI@NH2-MIL-53(Fe) (CPM) heterojunction material with excellent visible light absorption, efficient charge separation, and good stability, achieving highly efficient degradation of pharmaceutical and phenolic micropollutants in the application of photocatalysis.
Background:
1. To address the problem of water contamination by organic pollutants that are difficult to treat with conventional methods, previous researchers explored photocatalysts, but TiO2 is limited by its wide band gap, and existing MOF/g-C3N4 composites have unclear carrier transport mechanisms.
2. The authors in this study proposed an innovative method of in-situ growth of NH2-MIL-53(Fe) on g-C3N4/PDI to form heterojunctions, obtaining CPM composites with superior photocatalytic performance.
Research Content:
1. Synthesis:
The authors synthesized g-C3N4 by thermal condensation of melamine, MA by calcination of melamine, g-C3N4/PDI by calcination of PMDA and MA, NH2-MIL-53(Fe) by solvothermal method, and finally CPM composites with different ratios via solvothermal growth of NH2-MIL-53(Fe) on g-C3N4/PDI.
2. Characterizations:
1) No specific BET and pore size distribution results are mentioned.
2) SEM and TEM tests show that spindle-shaped NH2-MIL-53(Fe) is in close contact with g-C3N4/PDI laminates, with elements C, N, O, and Fe evenly distributed.
3) XRD confirms the crystal structure of NH2-MIL-53(Fe) is preserved in CPM; XPS reveals chemical states and interactions of elements; UV-vis DRS shows CPM has a wide visible light absorption range (up to 800 nm) with band gaps of 2.11-2.48 eV; PL and photocurrent tests indicate efficient charge separation; ESR detects •OH as main reactive species.
3. Application:
The material was tested in photocatalytic degradation of TC, CBZ, BPA, and PNP. Results show CPM-2 achieves 90% TC degradation in 1 h, 78% CBZ in 2.5 h, 100% BPA in 10 min, and 100% PNP in 30 min; 2 ppm BPA and PNP are degraded within 10 min. Optimal conditions are 0.2-0.4 g/L catalyst and 10 mM H2O2.
4. Mechanism:
Visible light excites e--h+ pairs; e- transfers from g-C3N4/PDI's CB to NH2-MIL-53(Fe)'s CB, h+ transfers reversely, reducing recombination. Fe3+ is reduced to Fe2+ by e-, which reacts with H2O2 to generate •OH, oxidizing pollutants. Band structure matching and good interface contact facilitate charge transfer.
Outlook:
This research successfully constructs a high-performance g-C3N4/PDI@MOF heterojunction photocatalyst, providing new insights for Fe-MOF-based heterojunctions in organic pollutant degradation, with potential for water remediation.
Construction of g-C3N4/PDI@MOF heterojunctions for the highly efficient visible light-driven degradation of pharmaceutical and phenolic micropollutants
Authors: Yuanyuan Li, Yu Fang, Zhenlei Cao, Najun Li, Dongyun Chen, Qingfeng Xu, Jianmei Lu
DOI: 10.1016/j.apcatb.2019.03.024
Link: https://www.sciencedirect.com/science/article/pii/S0926337319302401
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