| AVS 58th Annual International Symposium and Exhibition | |
| Thin Film Division | Monday Sessions |
| Session TF-MoA |
| Session: | Emerging ALD Applications |
| Presenter: | Matthieu Weber, Eindhoven University of Technology, Netherlands |
| Authors: | M.J. Weber, Eindhoven University of Technology, Netherlands A.J.M. Mackus, Eindhoven University of Technology, Netherlands M.A. Verheijen, Philips Innovation Services, Netherlands C. van der Marel, Philips Innovation Services, Netherlands W.M.M. Kessels, Eindhoven University of Technology, Netherlands |
| Correspondent: | Click to Email |
Recently, atomic layer deposition (ALD) has become the subject of great interest as a new way to synthesize supported metallic nanocatalysts (1, 2). In comparison to their single-metal counterparts, bimetallic nanoparticles (NPs) can present a higher selectivity and an enhanced catalytic activity. In this contribution, we present an innovative ALD process enabling the synthesis of supported bimetallic core-shell NPs. 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. In this work, Platinum-Palladium core-shell NPs were successfully deposited on Al2O3 using ALD of Pt and Pd. The selective growth property of noble metal ALD (3) has been exploited to cover Pt nanoclusters with a Pd shell. An ALD process using MeCpPtMe3 and O2 has been used to deposit Pt nanoclusters, and ALD with Pd(hfac)2 and H2 enabled to selectively cover them with a Pd shell. High Angle Annular Dark Field (HAADF) TEM images confirm the fact that bimetallic core-shell NPs of 3-4 nm were synthesized (on Al2O3 covered TEM windows). Information on the chemical state of the Pd and Pt was obtained from XPS analysis. Average values of the Pd shell thickness as obtained by a model analysis of the XPS data were found to be in agreement with the TEM data. This new process is expected to be also applicable to other Platinum group metals. The tailoring of such NPs by changing the ALD process parameters in order to obtain different particles sizes and compositions is also addressed. It is expected that the fuel cells industry, but also advanced sensors technologies, can benefit considerably from an enhancement of catalytic activity and selectivity of nanocatalysts prepared by ALD.
1: Stair, J. Chem. Phys. 2008, 128, 182507
2: Christensen et al., Small 2009, 5, No. 6, 750-757
3: Mackus et al., J. Appl. Phys. 2010, 107 (11), 116102-1/3