Principal Investigator Mircea Dinca
The development of safe and reliable electrical energy storage (EES) devices is instrumental for the large scale collection and distribution of clean energy from intermittent power sources such as solar and wind. A promising class of materials that can solve these challenges is metal-organic frameworks. These are crystalline solids with highly tunable structures that exhibit high surface areas and large internal volumes but generally lack electronic conductivity. We aim to develop general methods for the synthesis of electrically and/or ionically conductive crystalline microporous materials, with the ultimate goal of providing a new class of microporous electrodes for general use in EES devices such as Li-ion batteries and supercapacitors, in resistive sensing devices, or in ion selective membranes.
Metal-organic frameworks have traditionally been used for gas storage and separation, and much less attention has been devoted to their electronic properties. We are synthesizing new metal-organic frameworks (MOFs) that exhibit good charge mobility and conductivity. We have recently shown that the incorporation of tetrathiafulvalene moieties into a zinc-based metal-organic framework can produce solids with an intrinsic charge mobility of 0.2 cm2/Vs (above, left). This is the highest mobility ever observed in a MOF and is commensurate with the bulk charge mobilities of the best conducting polymers used in organic photovoltaics. The group is also actively exploring methods to engender electronic conductivity in a related class of materials called covalent-organic frameworks, and more generally, porous electroactive polymers. COFs have inherent π-stacked two-dimensional structures that can lend themselves to hole, electron, and potential one-dimensional ion mobility naturally (above, middle). We are also exploring systems with redox-active metals and softer ligands that form bonds with greater covalency and π-overlap with the metal orbitals. Students involved in this project design and synthesize new ligands, synthesize the targeted MOFs and COFs using solvothermal reactions, and measure physical properties with sophisticated techniques available either in house or through collaborators in the US or abroad (above, right). The development of conductive high-surface area materials could provide unique new architectures for organic photovoltaics, new membranes for rechargeable Li- and Na-ion batteries, new materials for potential-swing separation, and electrocatalysts for CO2 and O2 reduction.