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DTU is the leader in the field of establishing rare earth metal platinum alloy nanoparticles as catalyst for the ORR. However, a cheap and scalable synthesis method is lacking so far. The main obstacle is the very negative reduction potential of the rare earths which prohibits the utilization of the common nanoparticle synthesis methods.
thesis discusses and investigates several options of synthesizing PtxY and PtxY nanoparticles by novel synthesis
First, sodium dissolved in
liquid ammonia is used as a reducing agent and rapidly mixed with various early
transition, rare earth metal salts and platinum on carbon. After an annealing
treatment at high temperatures the respective platinum alloy nanoparticles are
obtained. However, the size distribution of the nanoparticles does not meet the
design criteria of ORR catalysts.
Secondly, the same principle is used by replacing liquid ammonia with a suitable organic solvent. Platinum rare earth metal alloy nanoparticles with an improved particle size distribution are obtained.
it is found for the first time that platinum and the respective rare earth
metal salts alloy at elevated temperatures in the presence of potassium vapor.
This method allows a fairly good control over the phase composition and
size distribution of the nanoparticles. The obtained Pt3Y/C and Pt2Gd/C nanocatalysts
were electrochemically testes and found to exhibit a higher ORR activity
than the responding commerical Pt/C catalyst. The importance of the annealing
temperature, precursor stoichoimetry and acid leaching is further investigated to
complete the understanding the role of the potassium vapor.
This method has the potential to be commercialized and eventually reduce the necessary amount of platinum in fuel cell systems and thus progressing their application and contribution towards a sustainable energy future.
|Publisher||Technical University of Denmark|
|Number of pages||170|
|Publication status||Published - 2019|