Sustainable Energy Storage and Conversion

Sustainable Energy Storage and Conversion

The foundation of this research is a material platform that we term conducting redox polymers (CRPs). CRPs are conducting polymers that have been decorated with redox active functional groups and they provide an attractive alternative for both catalysis and electrical energy storage. The conducting polymer backbone renders the material conductive and, hence, ensures electronic access to the entire materials. The redox active pendant groups, on the other hand, provide the material with additional functionality. For batteries the target is a well-defined redox potential, a stable redox conversion, and a high capacity to store charge. To that end quinones are ideally suited and significant focus is directed towards the development of quinone-based CRPs. In addition to a high charge storage capacity quinones show a high resilience towards the nature of the cycling ion and can be used in a multitude of cycling chemistries. Quinone-based CRPs may therefore be used for proton batteries, lithium ion batteries, sodium batteries, potassium batteries and calcium batteries, but each cycling chemistry require a unique CRP-design and we are continuously expanding our understanding on structural-functional relationships.

For CRPs derived for catalysis the functional groups should provide a binding site for the relevant substrate and, as we are targeting oxidative and reductive water splitting the binding site should bind water and protons, respectively. Iron-based molecular catalysts are amongst the most promising for water oxidation and a rich flora of catalysts has been derived and tested in homogeneous catalysis setting. We intend to immobilize the most promising iron-based molecular catalysts using the CRP platform in order to develop materials that can replace catalysts based on expensive and scarce nobel metals. For catalytic water reduction, i.e. the reduction of protons to hydrogen gas, CRPs with porphyrin pendant groups are targeted as metal porphyrins are well known catalysts for proton reduction. As the porphyrin ligand can accommodate almost any metal ion the porphyrin CRPs provide a unique opportunity to derive a molecular version of the Sabatier’s principle as each metal will have a unique substrate binding energy. Such rationalization, relating catalytic activity with a computationally available property, could provide a valuable tool for efficient design of molecular catalysts.