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.
All-Organic Batteries – Using quinone-based conducting redox polymers as cathode and anode materials we develop All-Organic proton batteries.
Organic Lithium Ion Batteries – We develop redox active organic materials to replace the cobalt-based cathode used in conventional lithium ion batteries with more environmentally benign alternatives. In addition we develop materials for other cycling chemistries such as sodium, potassium and calcium.
Proton Coupled Redox Reactions – All conversions between electrical and chemical energy rely on redox reactions coupled to chemical reactions. One of the most important class of coupled redox reactions is proton coupled redox reactions. In order to predict the outcome of such reaction it is essential to understand how electron and proton motions interconnects.
Iron-based catalysts for water oxidation – Several iron-based molecular catalysts for oxidative water splitting has been derived for homogeneous catalysis. For the next step molecular catalysts for heterogeneous catalysis need to be developed. To that end, we use conducting redox polymers as a platform to immobilize iron-based catalysts.
The Molecular Sabatier’s principle – Sabatier’s principle states the substrate binding energy to the catalyst should be neither too strong nor too weak and has been instrumental for the development of metal catalysts för heterogeneous catalysis. In this project we use porphyrin-based materials aimed for reductive water splitting to derive the molecular version of Sabatier’s principle using combined electrochemical and computational methods.
For more information please contact responsible researcher: Martin Sjödin