New catalysts
Cucore Ptshell Electrocatalysts for Fuel Cell application (Alexander Hartmann)
In order to reduce the high costs for platinum in fuel cell applications without sacrificing the activity, core shell particles with beneficial electrochemical properties are often used instead of supported platinum nanoparticles. A direct electrodeposition of stable platinum shells on non-noble metals were developed in our group, especially on copper as core. However this method is limited due to the scalability in the high surface area electrode. To overcome this problem, in our present research we develop an upscaling method for the Cu core Pt shell electrocatalysts through chemical deposition of copper on carbon support followed by redox exchange reaction with platinum.
To obtain the Cu@Pt/C electrocatalysts the copper particles are deposited on Vulcan X72 through reduction methods followed by a redox exchange reaction of the upper copper layers with platinum in varying pH. Besides, the influence of an additional heat treatment of the deposited copper particles is investigated for redox exchange reaction with platinum. The presence of Cu core Pt shell particles can be approved with XPS measurements. The prepared Cu@Pt/C electrocatalysts are characterized by electrochemical methods such as CV, RDE and CO-stripping experiments. Physical and morphological properties are determined with XRD, TEM and SEM measurements. Our future efforts will focus on the improvement of ORR activity by developing Cu@Pt/C
electrocatalysts with functionalized supports.
Core-Shell-Particles as catalyst in fuel cell apllicatons (Heba El Deeb)
Fuel cells are expected to be one of the major clean energy sources in the near future. However, the slow kinetics of electrocatalytic oxygen reduction reaction (ORR) and the high loading of Platinum (Pt) for the cathode material are the urgent issues to be addressed since they determine the efficiency and the cost of this energy source. Developing a Pt-based Core shell nanostructured catalysts exhibits promising ORR performance than the commercial catalysts. Core shell nanoparticles could be synthesized via different techniques, our work based on the formation of core shell nanostructure through selective electrochemical and chemical dissolution of the less noble metal from the surface of the bimetallic alloy and a noble metal enriched shell surface is formed.
Alternative materials as catalysts for the ORR (Thomas Erler)
Research in electrocatalysts for fuel cell applications is a major topic in our group. Hence alternative catalysts are based on non-noble metals (Ni, Co, Fe) or metal-free (N-doped) electrocatalysts on different carbon supports. Therefore it is very important to know which structures build the active side where the oxygen reduction reaction (ORR) take place and how good it is against to platinum based standards. The cost and availability of platinum is a big disadvantage of the used system.
Another big topic is the selected carbon species like CNT, carbon black or others and their influence on activity, selectivity and stability for our catalysis. The high temperature process for forming the active compounds should also be optimized like atmosphere, temperature and duration. Finally all of these prepared electrocatalysts has to be tested in our electrochemical measurements (CV, RDE) and for bigger setups in our fuel cell testing station by preparing electrode-membrane-assemblies (MEAs).