Carbon Dioxide Conversion to Synthetic Fuels
This research forms the basis of an ERC Starting Grant (DeCO-HVP) which started in October 2018.
The electrochemical reduction of carbon dioxide (CO₂) to synthetic hydrocarbons is a challenging, but potentially step changing, field of research. The ability to harness renewable electricity to regenerate high value hydrocarbon products, in a process akin to reverse combustion, would enable to carbon neutral route to continue to produce materials and fuels essential to modern society. Petrochemicals and fossil fuels are not only key to our transport and energy networks, but also supply key raw materials to produce plastics and other materials. CO₂ is a potential feedstock being generated as a pollutant, as well as residing in the atmosphere at an alarming concentration.
From an electrochemical perspective there are three leading routes to reducing CO₂; direct heterogeneous electrocatalytic reduction, homogeneous catalytic reduction, and mediated reduction (pictured left). All three of these approaches are under investigation in the Toghill Group. See the Decoupled CO2 Reduction page for more details.
Green hydrogen production
This research contributes to an ERC Horizon Europe EIC Pathfinder Grant (DualFlow) which started in October 2022. The Toghill Group joins a consortium of European members in Finland, Denmark, Ireland and the UK to develop an innovative route to green hydrogen using redox flow batteries whilst valorising the oxidation process via a suite of electro synthetic processes.
Hydrogen is increasingly seen as the solution to decarbonising and attaining net zero in our energy netowrks. However, only 1 % of global hydrogen is generated using electrolytic methods that are completely carbon neutral. this so called green hydrogen is a commodity in high demand, and governments across the world are pushing research and development to produce carbon neutral hydrogen as scale. See the Dual Flow Project pages for more details.
Redox Flow Batteries
Redox flow batteries (RFB) are rechargeable batteries typically designed to operate on the large scale to support renewable electricity generation as a flexible storage point. The underlying principle of a redox flow battery is very simple; two separate solutions containing electroactive species, ideally to high concentrations, are pumped through a battery cell, where electricity is used to charge them to a new state of charge. The two solutions do not mix, and are stored in their charged state in separate storage tanks. When that same electricity is then needed, the solutions are pumped through the same cell, but thermodynamically return to their original uncharged state, releasing the charge energy as electricity.
The leading commercial technology in this field uses vanadium in sulfuric acid as the charge carrier in solution. Vanadium has 4 oxidation states in acid, and these are exploited to give a battery with a voltage of 1.2 V. On the negative side the solution (electrolyte) cycles between a +2 and +3 state, and on the positive side, it cycles between a +4 and +5 state. The technology is increasingly integrating to renewable networks internationally, with megawatt hour batteries being routinely installed. They have up to 90 % efficiency, lifetimes exceeding 10 years, and are widely adaptable to give more power or more energy capacity, independently.
In the Toghill Group, we aim to explore ways of making VRBs and related technology more efficient and lower cost. Our main research focus is on finding new, alternative redox chemistry to replace vanadium in the RFB. Vanadium is an expensive metal and costs are rising steeply. Furthermore, it can only attain a low voltage of 1.2 V, which coupled to a moderate concentration of just 2 mol/L max, the battery is very limited. The cost to implement a VRB is just far too high and unsustainable. We're looking to find low cost metal-organic complexes and electroactive organic compounds suitable for use as flow battery mediators. Organic compounds are made of abundant elements, and many metals coordinate to organic ligands to give electrochemical properties that can be tailored.
Analytical Methods
Kathryn will always have a soft spot for electroanalytical techniques, and so the Toghill Group will always feature analytical methods in its repertoire. Recent research has focussed on analytical strategies for determining hydrocarbon products generated in CO₂ reduction. The complex media used in electrochemical process limit their analysis in conventional chromatographic instruments. The wide range of potential products in low concentrations also complicated the analysis of CO₂ reduction reactions.
To-date, work has taken place to develop an electrochemical approach to determine formaldehyde on the micromolar (ppb) levels. Analytical protocols utilising Ion Chromatography, NMR, Gas Chromatography and HPLC have also been established in the group, using the range of state-of-the-art facilities available in the Department of Chemistry.
Our group has developed methods to utilise electrochemical Mass Spectrometry in recent years, designing cells suited to electrolysis and direct evaluation of dissolved volatile products (gasses and alcohols) in a quadropole mass spectrometer (Hiden). Further to this we explore reactor designs and sampling strategies for the range of environments necessary for effectively studying CO2 reduction.
Electroanalytical Sensors
These past years members of the group have been developing biosensors for detecting biomarkers for kidney disease. In April 2023 we filed a patent for a new creatinine sensing platform that was cheap and able to determing creatinine levels in urine rapidly and easily. We have also been on the iCURe journey, seeking out a way to bring the sensor to market.