Ten-Million-Fold Increase in the Electrical Conductivity of a MOF by Doping of Iodine Into MOF Integrated Mixed Matrix Membrane.

ABSTRACT

The development of electrically conductive membranes is essential for advancing future technologies like electronic devices, supercapacitors, and batteries. Newly synthesized doubly interpenetrated 3D-Cd-MOF (Metal-Organic-Framework) containing angular tetra-carboxylate is found to display very poor electrical conductivity (10-11 S cm-1). However, it exhibits an exceptional ability to adsorb I2 (I2@Cd-MOF) which shows increased electrical conductivity of the order of 10-8 S cm-1. Following these results, the Cd-MOF is integrated into the PVDF-PVP (Polyvinylidene fluoride-Polyvinylpyrrolidone) polymeric mixed matrix membrane (MMM) and explores their I2 adsorption capabilities and electrical conductivities before and after I2 adsorption. Four polymeric MMMs with the loading of Cd-MOF 0, 20, 40, and 50% are tested for their I2 adsorption ability and their respective electrical conductivities. The 50% Cd-MOF-loaded MMM is found to exhibit higher adsorption of I2 (685 mg g-1) and significant enhancement in conductivity from 10-11 to 10-4 S cm-1. The raise in the electrical conductivity by 10 million times is attributed to the synergistic interactions between I2, Cd-MOF, PVDF, and PVP polymers as well as the increase in the concentration of charge carriers (holes) within the frameworks. This work serves as blueprint for controlling charge transfer in MMM to tune their electrical conductivity which opens a large window for advanced device applications.