In Situ Multicolor Imaging of Photocatalytic Degradation Process of Permanganate on Single Bismuth-Based Metal–Organic Frameworks

• Published in: Inorganic chemistry Vol. 63; no. 7; pp. 3221 - 3228
• Main Authors: Li, Yanhao, Ye, Wenyou, Yu, Haili, He, Yi
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.02.2024
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c03248

Bismuth-based metal–organic frameworks (Bi-MOFs) have emerged as important photocatalysts for pollutant degradation applications. Understanding the photocatalytic degradation mechanism is key to achieving technological advantage. Herein, we apply dark-field optical microscopy (DFM) to realize in situ multicolor imaging of the photocatalytic degradation process of permanganate (MnO4 –) on single CAU-17 Bi-MOFs. Three reaction kinetic processes such as surface adsorption, photocatalytic reduction, and disproportionation are revealed by combining the time-lapsed DFM images with optical absorption spectra, indicating that the photocatalytic reduction of purple MnO4 – first produces beige red MnO4 2– through a one-electron pathway, and then MnO4 2– disproportionates into yellow MnO2 on CAU-17. Meanwhile, we observe that the deposition of MnO2 cocatalysts enhances the surface adsorption reaction and the photocatalytic reduction of MnO4 – to MnO4 2–. Unexpectedly, it is found that isopropanol as a typical hole scavenger can stabilize MnO4 2–, avoiding disproportionation and causing the alteration of the photocatalytic reaction pathway from a one-electron avenue to a three-electron (1 + 2) process for producing MnO2 on CAU-17. This research opens up the possibility of comprehensively tracking and understanding the photocatalytic degradation reaction at the single MOF particle level.