Speaker: Bernard Dam
Date: 4th June 2013
Venue (remains to be confirmed): TPM Building Lecture Room C
Fluctuating sustainable energy sources necessitate the development of large scale storage options. Electrical storage is expensive, volatile, heavy and requires a large volume. The conversion of sunlight into fuel is an attractive approach to this problem. We focus on the solar-induced water splitting. The hydrogen can either be used directly as a storage medium or can be reacted with CO2 to create a liquid fuel reverse water gas shift and Fischer Tropsch type synthesis.
The development of solar water splitting devices has been the focus of many researchers recently.Devices with separate electrodes for the production of oxygen and hydrogen are favored, to avoid recombination losses and separation penalties. Recent achievements on catalysts have resulted in various composite photoelectrodes for which oxygen or hydrogen evolution are no longer the main performance-limiting factors. In those cases, efficient light absorption and charge separation are the issues to be addressed.
By combining BiVO4 photoanode with a PV solar cell developed in the group of professor Zeman, a photo-anode was obtained with a larger than 5% solar-to-hydrogen efficiency. Since only the oxide is exposed to water, this device is expected to have the required lifetime of over 15 year and we therewith hold the world record. Analyzing the efficiency of this hybrid device it is the purpose of the research to show that higher efficiencies are within reach.
The most important distinction between a solar PV and a photoelectrichemical cell is that the efficiency of the former device is determined by the product of potential and current (FF). The efficiency of the photoelectrochemical cell is determined by the fact that a minimum potential is needed which is determined by the nature of water splitting reaction.
Notes about the speaker
Since 2009 Bernard Dam is the head of the MECS group at the Delft University of Technology which focuses on Materials for Energy Conversion and Storage. In addition to the thin film metal hydride research on storage, sensing and membranes, his group specializes in photoelectrochemical water splitting and the development of high-efficient oxide photoanodes. His research interests on the relation between growth, (defect)structure and physical properties of thin film oxides and hydrides.