Jiabao Gu,Qianwen Li,Xuanyu Long,Xiaohan Zhou,Nan Liu,Zequan Li
In this study, we synthesized the MBSr (MIL-88A(Fe)/BiOBr/SrFe 12 O 19 ) dual Z-scheme heterojunction via an accessible hydrothermal method and investigated the photocatalytic performance of MBSr composites for Rhodamine B (RhB) and Methylene blue (MB). The MBSr-1% photocatalyst exhibited excellent photocatalytic performance, resulting the degradation rate of RhB reached approximately 96.2% within 60 min, which was higher than that of M88 (34%), BiOBr (89%) and M88/BiOBr-7% (93.7%) composites. And the MBSr-1% could eliminate 90.1% of MB within 90 min, which displayed the best photodegradation efficiency of prepared photocatalysts. The enhanced photocatalytic performance can be ascribed to the formation of dual Z-scheme heterojunction, which enhanced visible-light absorption and facilitated the transfer of photoinduced carriers. The MBSr-1% was proved to have excellent stability and reusability after six-recycling run. Furthermore, the major reactive species were h + , •O 2 − and •OH by radical trapping experiments. Finally, a possible photocatalytic pathway and mechanism of MBSr photocatalysts was proposed.
Zhenfei Yang,Xinnian Xia,Luhua Shao,Longlu wang,Yutang Liu
Herein, Ag 3 PO 4 /mixed-valence MIL-88A(Fe) [AMM] Z-scheme heterojunctions with an in-situ-generated photo–Fenton process were successfully constructed. The optimized AMM-20 heterojunctions show the maximum rate of photocatalytic TC degradation, which is 2.5 and 6.6 times of pristine Ag 3 PO 4 and MIL-88A(Fe). The electronic and band structures of Ag 3 PO 4 , MIL-88A(Fe), m-MIL-88A(Fe) and AMM heterojunctions were deeply investigated by both experimental and theoretical simulation. The Z-scheme transfer pathway greatly accelerates the transfer rate of charge carriers and effectively inhibits the photocorrosion, leading to the improvement of photocatalytic activity and photostability. Moreover, the adjustment of the Fe II /Fe III ratio of mixed-valence MIL-88A(Fe) further enhances the photocatalytic activity of the hybrid photocatalysts, benefiting from the promotion of the efficiency of the in-situ-generated photo-Fenton process. The Z-scheme transfer route coupling with an in-situ-generated photo–Fenton process was verified by the free radical trapping experiment, in-situ XPS measurement, in-situ ESR measurement, and coumarin fluorescence analysis. The degradation pathways of TC were determined through LC-MS analysis and theoretical calculation. Furthermore, the toxicity of intermediates was evaluated by QSAR prediction.
Herein, a photo-self-Fenton system of resorcinol-formaldehyde resins/MIL-88A(Fe) (RF/88A) S-scheme heterojunction was successfully established to in-situ generate and activate H 2 O 2 toward tetracycline (TC) degradation and sterilization under visible light illumination. As a result, the 35 %-RF/88A (the mass ratio of RF to 88A was 35 %) can remove most TC and kill approximately 100 % E. coli and S. aureus . Notably, the composites presented superior repeatability and wide pH application range. Fukui index identified the reaction sites of TC molecule and quantitative structure-activity relationship (QSAR) forecasted intermediates toxicity. Density functional theory (DFT) calculations were performed to investigate electron transfer mechanism of the heterojunctions on a molecular scale. Such a S-scheme charge transfer route was also proved by in situ irradiated X-ray photoelectron and electron paramagnetic resonance measurements. In summary, this research innovatively provides deep insights into the in-situ generation and activation of H 2 O 2 and exhibited an environmentally friendly way toward pollutant degradation and sterilization.
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