The Impact of Structural Defects on Iodine Adsorption in UiO-66

Radioactive I-2 (iodine) produced as a by-product of nuclear fission poses a risk to public health if released into the environment, and it is thus vital to develop materials that can capture I-2 vapour. Materials designed for the capture and storage of I-2 must have a high uptake capacity and be stable for long-term storage due the long half-life of I-129. UiO-66 is a highly stable and readily tuneable metal-organic framework (MOF) into which defect sites can be introduced. Here, a defective form of UiO-66 (UiO-66-FA) was synthesised and the presence of missing cluster moieties confirmed using confocal fluorescence microscopy and gas sorption measurements. The uptake of I-2 vapour in UiO-66-FA was measured using thermal gravimetric analysis coupled mass spectrometry (TGA-MS) to be 2.25 g g(-1), almost twice that (1.17 g g(-1)) of the pristine UiO-66. This study will inspire the design of new efficient I-2 stores based upon MOFs incorporating structural defects.