Platinum (Pt) nanoparticles on carbon support (Pt/C) are regarded as the most catalytically active materials for oxygen reduction reaction (ORR) activity in proton exchange membrane fuel cells (PEMFCs). However, the main drawback hindering PEMFC commercialization is the cost and scarcity of platinum necessitating low platinum loading into the fuel cell leading to low activity. There has been significant research looking into the synthesis of structured Pt-M alloys (M = Ni, Co, Fe, or Cu) to improve catalysis activity and durability with reduced platinum use. These nanostructured or shaped Pt-M alloys include three dimensional nanocrystals dominated by low index facets, hollow structures rich with Pt, or one dimensional nanostructures like Pt-M alloy nanowires.
Hollow structures such as Pt-M alloy nanoframes and nanowires are more appealing because most of the Pt on the frames contributes to the catalytic activity as opposed to solid nanocrystals with buried Pt. The use of Pt-M alloy skin or skeleton nanoframes/nanowires is necessary for the reduction of platinum loading to reduce cost but still maintaining high activities and durability, essential for PEMFCs. Here, Pt-Ni alloy nanoframes and naowires are synthesised through a co-reduction method starting with solid shaped nanostructures and etching the sacrificial nickel to realise nanoframes. The synthesised nanocrystals are characterised via electron microscopy for morphology, crystallinity, and elemental composition; x-ray diffraction for phase identification and crystallinity, and lastly x-ray photoemission spectroscopy to probe oxidation states of the Pt and Ni. The Pt-Ni nanoframes/nanowires are then supported on a high surface area carbon to complete the catalyst and to perform catalytic activity through electrochemical methods using thin-film rotating disc electrolyte (RDE) measurements.
Audience Takeaway Notes:
- This study will educate the audience about the important role fuel cells play on the renewable energy mix
- The audience will also learn about the synthesis chemistry of structured metal alloys
- Help other researchers understand how shaped metal alloys can improve ORR
- Finally, how reducing cost of renewable energy sources can speed up their deployment/usage