Enhancing the spatial separation of photogenerated charges on Fe-based MOFs via structural regulation for highly-efficient photocatalytic Cr(VI) reduction

• Published in: Journal of hazardous materials Vol. 441; p. 129875
• Main Authors: Zhang, Hao, Luo, Yu-Hui, Chen, Feng-Yu, Geng, Wu-Yue, Lu, Xin-Xin, Zhang, Dong-En
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.01.2023
• Subjects: absorption; adsorption; Cr(VI) reduction; Iron; irradiation; ligands; light; Metal-organic framework; Photocatalysis; Structural regulation; Metal-organic framework; Iron; Structural regulation; Cr(VI) reduction; Photocatalysis
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2022.129875

Although iron-based metal-organic frameworks (Fe-MOFs) have displayed the photocatalytic activity, there is still abundant room for improving their photocatalytic performance through tuning the structures. In this work, four novel iron-based metal-organic frameworks (Fe-MOFs) were successfully synthesized via ligand modulation for better photocatalytic Cr(VI) reduction, in which MTBDC-TPT-Fe had the highest catalytic activity (MTBDC = 2,5-bis(methylthio)terephthalic acid, TPT = 2,4,6-tri(4-pyridyl)− 1,3,5-triazine). The boosted photocatalytic reduction may be mainly ascribed to the enhanced electron push-pull effect between iron-oxygen clusters and organic ligands. The introduction of -SCH3 groups can enhance the light absorption and donate electrons to iron center under visible-light irradiation, meanwhile the separation and transfer of photogenerated charge carriers can be enhanced resulting from the electron-pulling effect when introducing TPT. Moreover, enhanced specific surface areas and positive skeleton charge due to the introduction of TPT may improve active sites exposure and Cr(VI) adsorption, thereby enhancing photocatalytic Cr(VI) reduction activity without the presence of any assisted scavengers. In addition, the photocatalytic mechanism (i.e. active species) were also studied and presented. This work confirmed an effective structure-performance regulation strategy on Fe-MOFs for photocatalytic Cr(VI) reduction. [Display omitted] •Four novel Fe-MOFs are constructed by ligand modulation for superb photocatalytic Cr(VI) reduction.•The introduction of -SCH3 group can significantly improve the light absorption ability of Fe-MOF.•TPT ligand can improve the separation and migration of charge carriers through electron-pulling effect.•Larger pores and more positive skeleton formed by TPT introduction are favorable for the adsorption of Cr(VI) substrate.•The e-, ·OH radicals, and O2·- radicals are main active species in the Cr(VI) reduction process.