- When cars produce water as exhaust: Scientists at the TU Berlin are working with BMW to develop novel catalyst materials for high-performance hydrogen fuel cell cars
Hydrogen fuel cells are considered a hope in the discussion about the vehicle drives of the future. Their biggest advantage: water and heat are the only “waste products” they emit. One of the current biggest drawbacks is the cost, which depends not least on the very expensive material platinum needed for the catalyst in the fuel cell. Decreasing the platinum content in the fuel cell, but also decreases the electrical power generated even faster. Prof. Dr. Peter Strasser from the Technical University of Berlin and his colleagues in the field of electrocatalysis and materials, in cooperation with scientists from BMW, have now succeeded in chemically designing the catalyst support material in an automotive-grade hydrogen fuel cell. that despite a small board use high electrical power is generated. Their results have now been published in the renowned Journal Nature Materials.
Fuel cell vehicles are ultimately also e-cars. The difference: The required power is not stored in a battery, but generated on board while driving as needed. At two separate electrodes of the fuel cell, hydrogen, which is carried in a special tank in the car, reacts with the oxygen in the ambient air. This creates electricity and water. The generated power is consumed or buffered in a small backup battery. For the electrochemical reaction at the cathode of the fuel cell, a platinum catalyst is needed. “Even if the fuel cell cars currently on the market use only 30 grams of platinum per fuel cell,
The problem: The platinum nanoparticles must be applied in an extremely uniform distribution with a so-called ionomer, a hydrogen-ion (proton) conductive plastic, on the carbon support substance. The less platinum nanoparticles are to be used, the more important is the uniform distribution of the ionomer so that all the reactants involved have access to the platinum particles that act as the catalyst. A non-uniform ionomer distribution results in a high resistance to the transport of oxygen molecules, which in turn leads to a high loss in the generated electrical voltage and power. “In the work published now, we describe the preparation of a novel, chemically modified carbon support material with tailored surface properties. This has enabled us to achieve an unprecedented uniform distribution of the ionomer on this carrier material. That’s how we achieve high power densities with low board usage, “says the scientist. This tailored catalytic converter achieved unprecedented performance and stability in fuel cell production – with at least 50 percent less platinum.
“The special thing about our approach: We worked directly with a car-friendly fuel cell so that our results have the opportunity to flow directly into the next generations of the fuel cell car,” says Peter Strasser about the success.