Facilitation of the visible light-induced Fenton-like excitation of H2O2 via heterojunction of g-C3N4/NH2-Iron terephthalate metal-organic framework for MB degradation

- A heterojunction structure of hybridized g-C3N4 and a stable iron-based MOF was reported for the first time.
- 100% of visible light-induced MB degradation was achieved within 120 min.
- The synergy index of the lp-2 / visible light / H2O2 system was enhanced by 306%.
- Dramatically reduced recombination rate of photo-induced e−-h+ pairs on g-C3N4 and facilitated hydroxyl free radical generation on the lp-2 are verified by the electron spin resonance technique and photoluminescence analysis.
- The mechanism of enhanced photo-induced Fenton-like activation of H2O2 was illustrated.

g-C3N4/NH2-Iron terephthalate metal-organic framework heterojunction for visible light-induced Fenton-like excitation of H2O2 for MB degradation was investigated in this work. The g-C3N4/NH2-MIL-88B(Fe) (namely lp-x composite) was hydrothermally synthesized and characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, UV-vis diffused reflectance spectroscopy, spin-trapping electron paramagnetic resonance and photoluminescence analysis. 100% of MB photodegradation was achieved by the lp-2 in 120 min under visible light, much greater than the parent g-C3N4 and NH2-MIL-88B(Fe), individually. The synergistic index in the lp-2/visible-light/H2O2 system reached as high as 305%. The excitation of H2O2 over the lp-2 composite is clarified to go through (i) the direct and (ii) the photo-induced Fenton-like reactions, while the latter is greatly facilitated by the formation of the g-C3N4/NH2-MIL-88B(Fe) heterojunction. In the lp-2 composite, the photoelectron transfers efficiently from the CB of g-C3N4 to NH2-MIL-88B(Fe) for enhanced Fenton-like excitation of H2O2, rather than eliminates through e−-h+ pair recombination on g-C3N4, verified by the photoluminescence analysis and electron spin resonance technique. This work demonstrates the first example of facilitating Fenton-like excitation of H2O2 via introduction of g-C3N4 to stable amine functionalized Fe-centered MOF for visible light-induced photodegradation.

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