An interdisciplinary research team at the Technical University of Munich (TUM) has designed size-optimized platinum nanoparticles for catalysis in fuel cells that exhibit specific and mass activities twice as high as the best commercially catalysis available today (Tanaka commercial Pt/C). A paper on their work is published in the journal Angewandte Chemie.
In fuel cells, hydrogen reacts with oxygen to produce water, generating electricity in the process. Catalysts at the electrodes are required in order to optimize this conversion. Platinum plays a central role in the oxygen-reduction reaction. However, the platinum used in fuel cells is rare and extremely expensive, which has been a limiting factor in applications up to now.
Searching for an ideal solution, the TUM team created a computer model of the complete system. The central question: How small can a cluster of platinum atoms be and still have a highly active catalytic effect?
It turns out that there are certain optimum sizes for platinum stacks.—Roland Fischer, Professor for Inorganic and Organometallic Chemistry
Particles measuring about one nanometer and containing approximately 40 platinum atoms are ideal.
Platinum catalysts of this order of size have a small volume but a large number of highly active spots, resulting in high mass activity.—Aliaksandr Bandarenka, Physics of Energy Conversion and Storage
Interdisciplinary collaboration at the Catalysis Research Center (CRC) was an important factor in the research team’s results. Combining theoretical capabilities in modelling, joint discussions and physical and chemical knowledge gained from experiments ultimately resulted in a model showing how catalysts can be designed with the ideal form, size and size distribution of the components involved.
In addition, the CRC also has the expertise needed to create and experimentally test the calculated platinum nano-catalysts.
The experiment exactly confirmed the theoretical predictions. The performance of the new catalyst is still not adequate for commercial applications, since the current 50% reduction of the amount of platinum would have to increase to 80%, said Dr. Batyr Garlyyev, lead author.
In addition to spherical nanoparticles, the researchers hope for even higher catalytic activity from significantly more complex shapes.
Batyr Garlyyev, Kathrin Kratzl, Marlon Rück, Jan Michalicka, Johannes Fichtner, Jan M. Macak, Tim Kratky, Sebastian Günther, Mirza Cokoja, Aliaksandr S. Bandarenka, Alessio Gagliardi and Roland A. Fischer (2019) “Optimizing the Size of Platinum Nanoparticles for Enhanced Mass Activity in the Electrochemical Oxygen Reduction Reaction” Angewandte Chemiedoi: 10.1002/anie.20190492