Paper TF+EN-MoM10
Synthesis of Pd and Pt Nanoparticles by Atomic Layer Deposition for Catalysis Applications

Monday, October 28, 2013, 11:20 am, Room 104 A

Noble metal nanoparticles (NPs) are known to be very efficient catalysts and are of crucial importance to pharmaceutical, (petro)chemical and environmental industries. Although ALD was primarily developed to deposit conformal thin films, metals have the tendency to form nanoclusters on the substrate during the initial cycles of the process. Using this Volmer-Weber growth mode, Pd and Pt NPs supported on Al₂O₃ were synthesized with the aim to design efficient model catalysts systems. The Pd process was based on Pd(hfac)₂ (hfac= hexafluoroacetylacetonate) as the precursor, and H₂ plasma as co-reactant, whereas the Pt process was carried out with the use of MeCpPtMe₃ and O₂ plasma. The deposition temperature was 100ºC. The Pd and Pt NPs resulting from the ALD nucleation stage have been characterized by High Angle Annular Dark Field Transmission Electron Microscopy (HAADF-TEM). High density values of ̴ 10¹² NPs/cm² and narrow size distribution (in particular for Pd) of 2-3 nm NPs have been obtained on alumina substrates, and depositions carried out with one year time interval have shown excellent reproducibility. The tailoring of such NPs by changing the ALD process parameters in order to obtain different particle sizes and composition is also demonstrated. Furthermore, preliminary experiments have shown that these noble metal NPs are efficient as photocatalysts and towards the CO-oxidation. These results open up prospects in the engineering of metallic nanoparticles for fuel cells and micro-reactors applications, for which ALD can be feasible.