Dr Mark Symes
- Senior Lecturer (School of Chemistry)
The Symes group is interested in all aspects of energy conversion in chemical systems. In the first instance, this means using electrical, photochemical and sonochemical inputs to drive chemical reactions that might not happen otherwise. A cornerstone of our approach is using renewable (or potentially renewable) energy sources to drive unfavourable or slow chemical reactions to deliver fuels and other high-commodity substances.
Renewable routes to nitrogen fixation
A primary target of our investigations is the fixation of nitrogen to ammonia. Ammonia is used mainly for fertilisers but is also important in the manufacture of pharmaceuticals, explosives and plastics. Beyond these existing uses, it is also conceivable that dinitrogen-reduction products such as ammonia and hydrazine might one day be used as fuels, where the end products of combustion are simply nitrogen and water. Hence a green energy storage cycle would be possible if the hydrogen that was originally used to reduce the nitrogen was obtained from water using renewable energy inputs (e.g. solar-driven electrochemical or photoelectrochemical water splitting).
In effect, the nitrogen would be used as a carrier for the hydrogen produced from water splitting in much the same way as CO2 would do in an anthropogenic carbon cycle. A key advantage of using N2 for this purpose over CO2 is that there is significantly more N2 available in the atmosphere for this fixation. Moreover, thermodynamically speaking, the energy required to reduce N2 to NH3 compares favourably with that required to reduce CO2 to its most easily obtained fuel, formic acid. However, the activation energy for nitrogen reduction is prohibitively large and methods for generating NH3 are generally sluggish. Our research program looks at new ways to overcome this energy barrier to nitrogen fixation, using scalable electrochemical, photochemical and sonochemical methods.
More recently, we have also begun to explore nitrogen fixation by the oxidation of nitrogen to nitrite. This allows much more mild conditions to be employed than with nitrogen reduction to ammonia (open to air and water and at room temperature and pressure). Once nitrite is produced, its central position in the nitrogen cycle allows its ready conversion to nitrogen species in other oxidation states. We use synthetic metal-ligand coordination complexes to achieve these nitrogen oxide interconversions, a topic we recently reviewed.
- “Efficient Electrocatalytic Water Oxidation at Neutral and High pH by Adventitious Nickel at Nanomolar Concentrations.” I. Roger and M. D. Symes J. Am. Chem. Soc. 2015, 137, DOI: 10.1021/jacs.5b08139.
- “Converting Between the Oxides of Nitrogen Using Metal-Ligand Coordination Complexes.” A. J. Timmons and M. D. Symes Chem. Soc. Rev. 2015, 44, 6708-6722.
- “Decoupled catalytic hydrogen evolution from a molecular metal oxide redox mediator in water splitting.” B. Rausch, M. D. Symes, G. Chisholm and L. Cronin Science 2014, 345, 1326-1330.
- “Decoupling Hydrogen and Oxygen Evolution During Water Splitting Using a Proton-Coupled-Electron Buffer.” M. D. Symes and L. Cronin Nature Chem. 2013, 5, 403-409.
- “Bidirectional and Unidirectional PCET in a Molecular Model of a Cobalt-Based Oxygen-Evolving Catalyst.” M. D. Symes, Y. Surendranath, D. A. Lutterman and D. G. Nocera J. Am. Chem. Soc. 2011, 133, 5174-5177.
- Lord Kelvin Adam Smith Research Fellowship (University of Glasgow), 10 K per annum.
- MDS is currently a Co-I on an EPSRC-funded grant related to the use of Electron-Coupled-Proton Buffers (ECPBs) in water splitting applications (Reference PEB 61602, FEC £455,000).
- MDS was a named Co-I on the University of Glasgow College of Science and Engineering’s successful Small Equipment bid in late 2012 (EPSRC reference 62131). This allowed MDS to purchase £30,000 of necessary equipment for his group.
“S4 – Electrochemistry for a sustainable future”
Selected recent talks
7. Low pH Electrolytic Water Splitting Using Earth-Abundant Metastable Catalysts That Self-Assemble in Situ, Electrochem2014, Loughborough, UK, September 2014.
6. Low pH Electrolytic Water Splitting Using Earth-Abundant Metastable Catalysts That Self-Assemble in Situ, 65th annual meeting of the International Electrochemical Society, Lausanne, Switzerland, August 2014.
5. Low pH electrocatalytic water splitting with first row transition metals, 2014 RSC Scottish Dalton Meeting, St. Andrews University, UK, March 2014.
4. Electron-Coupled Proton Buffers for electrolytic water splitting, ECOST meeting CM1202, University of Ulm, Ulm, Germany, December 2013.
3. Catalysis and mediation in electrolytic water splitting, Lorentz Center, University of Leiden, Netherlands, October 2013.
2. Decoupling Hydrogen and Oxygen Evolution During Water Splitting Using a Proton-Electron Buffer, RSC Macrocyclic and Supramolecular Conference 2012 (MASC2012), QMUL, London, UK, December 2012.
1. Decoupling Hydrogen and Oxygen Evolution During Water Splitting Using a Proton-Electron Buffer, Frontiers in Metal Oxide Cluster Science 2012, Lanzarote, Spain, November 2012.
4. Does powering the planet have to cost us the Earth? The Glasgow Skeptics Society, Glasgow, August 2014 (public lecture and question-and-answer session).
3. Reliable Renewable Fuels - storing renewable energy, Dunkeld and Pitlochry Cafe Scientifique, Dunkeld, October 2013 (public lecture and question-and-answer session).
2. Reliable Renewable Fuels, Glasgow Cafe Scientifique, Glasgow, November 2012 (public lecture and question-and-answer session).
1. The Physics of Solar Fuels, Institute of Physics 38th Stirling Physics Meeting, University of Stirling, Stirling, May 2012.