Solar Energy Conversion and Hydrogen Production
Key staff: Dr Bruce Alexander
Semiconductor nanoparticles can be used to harness solar energy either in photovoltaic cells or to facilitate a chemical reaction, such as the production of hydrogen or photo-oxidation of organic pollutants.
Absorption of light by semiconductor materials leads to the formation of reactive charged species. The generation of charged species depends on the properties of the semiconductor, such as the band gap and energetic positions of the conduction and valence bands. Currently, the most widely employed photocatalyst is TiO2, which absorbs only the small fraction of the solar spectrum that corresponds to UV light. Work is ongoing to produce photocatalysts that are responsive to a larger range of light, thereby increasing the efficiency at which the catalyst can harness solar light.
Solar hydrogen production
If carbon emissions targets are to be met, it is imperative that new, clean, renewable fuel sources are found. Hydrogen is one possible fuel because its combustion produces only energy and water: it is therefore non-polluting. However, currently most hydrogen comes from natural gas supplies and is therefore hardly carbon neutral. It is clear, then, that a more sustainable source is needed. Using a photocatalyst and solar energy, it is possible to split water into hydrogen and oxygen, thereby offering a clean, renewable and sustainable source of hydrogen.
Recent and current projects
- Development of thin films of iron oxide and tungsten trioxide for solar hydrogen production.
- Synthesis of novel mixed metal oxide materials as visible-light activated photocatalysts.
- Carbon doping of Fe2O3 through flame photolysis.
- Fabrication of electrochromic films based on nanoparticulate metal oxides.
- Destruction of organic pollutants in wastewater by photocatalysis at semiconducting electrode surfaces.
- Synthesis of molecular electrocatalysts for oxygen reduction.
Publications
Alexander, B. D., Crayston, J. A. and Dines, T. J. (2007). Cyclic voltammetry and spectroelectrochemical study of nickel and cobalt diphenyltetraazaannulene. Journal of Electroanalytical Chemistry, 605, 109–117.
Alexander, B. D., Kulesza, P. J., Rutkowska, I. A., Solarska, R. and Augustynski, J. (2008). Metal oxide photoanodes for solar hydrogen production. Journal of Materials Chemistry (invited paper), accepted for publication.
Jorand Sartoretti, C., Alexander, B. D., Solarski, R., Rutkowska, I. A., Augustynski, J. and Cerny, R. (2005). Photoelectrochemical oxidation of water at transparent ferric oxide film electrodes. Journal of Physical Chemistry B, 109, 13685–16392.
Jorand Sartoretti, C., Ulmann, M., Alexander, B. D., Augustunski, J. and Weidenkaff, A. (2003). Photoelectrochemical oxidation of water at transparent ferric oxide file electrodes. Chemical Physics Letters, 379, 194–200.
Solarska, R., Alexander, B. D. and Augusttnski, J. (2004). Electrochomic and structural characteristics of mesoporous WO3 films prepared by a sol-gel method. Journal of Solid State Elecyrochemistry, 8, 748–756.
Solarska, R., Alexander, B. D. and Augustynski, J. (2006). Electrochromic and photoelectrochemical characteristics of nanostructured WO3 films prepared by a sol-gel method. Comptes Rendus Chimie, 9, 301–306.