Visual identification of O-induced crystal structure transformation of single Zr-MOF by dark-field microscopy.

Understanding the structural transformation of photocatalysts under illumination provides detailed insights to solve the poisoning of photocatalysts. In this study, the O-induced transformation of crystalline structure in nanosized Zr-porphyrin metal organic frames (ZrTCPP MOFs) is confirmed by a dark-field microscopy (DFM) system. Under continuous illumination, the energy of excited ZrTCPP transfers to oxygen in the surroundings and generates O, which causes the nanosized crystal ZrTCPP to change into the amorphous state The crystalline structure of ZrTCPP corresponds to the multiple resonance peaks of the scattering spectra, and the amorphous structure corresponds to the single scattering peak. Therefore, the crystalline change is characterized by characteristic peaks changes in the scattering spectra under DFM, showing that a real-time and DFM imaging method is a good platform for monitoring the crystal structure transformation at the single particle level.