Graphene oxide based MEAs for the direct ethanol fuel cell

The direct ethanol fuel cell (DEFC) shows high potential for portable applications as alternative power source. Performance (activity), durability (stability) and costs of the DEFC catalyst and membrane are the challenges that need to be addressed in order to enhance the development of this emerging technology. This project investigates the application of new membranes and electrode concepts (MEAs) that rely on environmentally friendly polysaccharide based polymers in combination with graphene oxide. The key objectives are: - Development of new anode catalyst systems based on non-noble containing metals (i.e. by using edge and basal planes functionalized graphene based materials as substrates) with high activity and long-term stability using of various selected synthesis methods (i.e. impregnation-, instant-, polyol-, nanocapsule-, core-shell- or bromide anion exchange method) to achieve a controlled homogeneous deposition of catalyst nanoparticles on support material. - Development and optimization of cost effective synthesis procedure for nitrogen functionalized graphene oxide (GO-N) by ammonia and nitrogen plasma. - Development of new anion-exchange membrane composite materials with enhanced efficiency and durability at reduced cost (i.e. by using sustainable polysaccharide-based polymers and functionalized graphene oxides) by using simple papermaking and coating procedures. The progress beyond the state-of-the-art is secured by addressing the key objectives in close co- operation utilizing the partners latest discoveries and design a completely new, environmentally friendly and high performance direct alkaline ethanol fuel cell.

In recent years, the demand for renewable energy has increased enormously due to the limited availability of fossil fuels and high CO2 emissions. Fuel cells are considered one of the key technologies for the clean energy economy of the future. However, there are three critical technical barriers that limit the commercialization of fuel cells: 1) power/activity, 2) durability/stability and 3) cost. Alkaline direct ethanol fuel cells (ADEFCs) are easy to use, low cost and environmentally friendly. However, the performance of ADEFCs is limited on the one hand by the slow reaction kinetics of the electrochemical oxidation of ethanol at the anode and on the other hand by the ethanol leakage from the anode to the cathode. The ethanol leakage causes a mixed potential at the cathode and thus reduces the cell voltage. Consequently, these two effects cause a drastic reduction in the power density of ADEFC systems. Therefore, there is an extensive need for research to develop high-performance and stable catalysts for both the anode and the cathode, but also for high-performance membranes that are at the same time cost-effective. In this project "Graphene oxide based MEAs for the direct ethanol fuel cell" GO DEFC the focus was therefore on the improvement of catalysts and membranes by the addition of specially developed graphene derivatives. The intensive cooperation of the project partners from TU Graz, University of Ljubljana and University of Maribor ensured the progress against the state of the art for the development of the new, environmentally friendly direct ethanol fuel cell with high power density. The use of cost-effective active materials such as non-precious metal co-catalysts and transition metal oxides, but also the reduction of the amount of active material and the high activity, simultaneously reduced costs. In the single cell tests, the self-prepared graphene-modified membranes resulted in a higher power density than commercial membranes. The optimization of the electrodes, the production of the membrane-electrode unit and the influence of the flow field and the measurement parameters on the performance were successfully demonstrated. In addition to scientific know-how, the work on this project revealed the creation of awareness for renewable energy sources. The importance of resource management in everyday life could be internalized. The project team members were able to gain important non-scientific experience and thus also expand their horizons in the important area of soft skills. This includes especially the importance of collaboration and cooperation with others to reach the set goals as a team more easily than as an individual and to complement each other.