Qiufan Sun,Yuxiang Zhu,Yan Wang,Zhengtao Jia,Xiang Zhong,Jianfeng Yao
Three isostructural MIL-68(M)-NH 2 frameworks (M = In, Fe, or Al) featuring different metal centers were synthesized to investigate their photocatalytic activities for nitrogen fixation. The influence of the metal oxo clusters on the crystalline structures, morphologies, and optical characteristics was examined. MIL-68(In)-NH 2 (MNI) with one-dimensional microrod structures has a larger surface area than bulk MIL-68(Fe)-NH 2 (MNF) and spherical MIL-68(Al)-NH 2 (MNA), and achieves an ammonia generation rate (140.34 μmol g cat −1 h −1 ) ca . 3.4 and 1.6 times higher than those of MNF (37.25 μmol g cat −1 h −1 ) and MNA (87.5 μmol g cat −1 h −1 ), respectively. The superior performance can be attributed to its high crystallinity, strong coordination between the In−oxo clusters and ligands, and microrod morphology, which enhance electron transfer, improve mass transport, and extend visible light absorption. Moreover, MNI shows greater stability in ethanol aqueous solution than other sacrificial reagents, such as methanol, potassium sulfite, and triethanolamine. While slight surface corrosion of the microrods occurs in methanol and potassium sulfite solutions, complete collapse is observed in triethanolamine.
Chen Chen,Jianhao Qiu,Guanglu Xia,Lu Zhang,Yixin Li,Biyao Fang,Meng Liu,Jianfeng Yao
Utilizing metal–organic frameworks as templates to synthesize photocatalysts has garnered increasing attention thanks to their substantial advantages. In this study, Cu-doped ZnIn 2 S 4 with hollow tubular structures was ingeniously synthesized using MIL-68-NH 2 as a template for photocatalytic H 2 O 2 production in ambient air and pure water under visible light. The hollow tubular structures promote light penetration and reflection, furnish substantial accessible reactive sites and accelerate the diffusion of reactants and products. Cu doping notably varies the band configuration of ZnIn 2 S 4 , resulting in a narrower bandgap and a lower conduction band potential. Their cooperative effects enable a respectable H 2 O 2 production from oxygen reduction reactions. The hollow tubular ZnIn 2 S 4 and corresponding Cu-doped counterpart achieved high H 2 O 2 yields of 1153 and 1616 μmol·L −1 , respectively, 3.6 and 5.1 times-increase compared with that of ordinary ZnIn 2 S 4 prepared without MIL-68-NH 2 . This work would provide a new perspective on ZnIn 2 S 4 -based photocatalysts and provoke the study on the green synthesis of H 2 O 2 .
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