Spectroscopic investigations of gamma-ray irradiation effects on metal organic framework

The chemical and physical features of metal organic frameworks (MOFs) at a molecular level are of great merit to understand structure-property relationships and, consequently, to aid in the design of improved high value products. This paper reports on the processing of one MOF-type material, namely MIL-101(Cr), by gamma-ray irradiation at low doses up to 30 kGy. The optimum dose is determined to be 15 kGy, at which an increase in the adsorption of iodine of more than 40% is achieved in comparison with thermally activated un-irradiated MIL-101(Cr). Scanning electron microscopy, X-ray diffraction and the Brunauer-Emmett-Teller (BET) isotherms indicate a significant particle agglomeration and a preservation of both the unit cell topology as well as the mesoporous structure of MOF. Two-dimensional correlation Fourier transformation infrared and X-ray diffraction reveals that orientation is the driving force for structural alterations including water type, bonding and contents. These effects account for the increasing adsorption capacity of MOF after irradiation and suggest further exploitation of irradiation as a promising method for MOFs activation. [GRAPHICS] .