| AVS 64th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS+NS+SS-WeM |
| Session: | Plasma Processing for Nanomaterials & Nanoparticles |
| Presenter: | Joffrey Baneton, Université Libre de Bruxelles, Belgium |
| Authors: | J. Baneton, Université Libre de Bruxelles, Belgium Y. Busby, Université de Namur, Belgium W. Debouge, Université Libre de Bruxelles, Belgium G. Caldarella, Université de Liège, Belgium J.-J. Pireaux, Université de Namur, Belgium V. Debaille, Université Libre de Bruxelles, Belgium N. Job, Université de Liège, Belgium M.J. Gordon, University of California at Santa Barbara R.M. Sankaran, Case Western Reserve University F. Reniers, Université Libre de Bruxelles, Belgium |
| Correspondent: | Click to Email |
Nanoparticles composed of one or more metals particularly platinum (Pt) are used as electrocatalysts in hydrogen fuel cells for the cathodic reduction of dioxygen [1]. Several challenges remain in their synthesis including controlling their morphological features (e.g. size, shape, etc.), maximizing the amount of Pt exposed while minimizing the overall amount of the expensive metal, and eliminating the presence of organic capping groups or other contaminants that cover the active surface.
Here, different atmospheric plasma devices including a microplasma and a radio-frequency (RF) plasma torch are shown to be capable of producing Pt and Pt-based alloy nanoparticles without any organic capping molecules and minimal chemical additives. The as-synthesized nanoparticles are characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) to assess their chemical purity and morphology. We find that when using the microplasma to reduce a Pt precursor in solution, small and non-agglomerated Pt nanoparticles can be directly produced in liquid phase (organic or water based). By controlling the initial amount of the Pt precursor dissolved in solution and the charge injected in the system, the nanoparticle concentration can be tuned [2]. Moreover, this methodology can be applied to bimetallic alloys to reduce the amount of Pt in the electrocatalyst.
In comparison, when using a RF plasma torch, Pt nanoparticles can be produced in the solid phase by plasma reduction of a Pt precursor dispersed on the surface of a carbon support (carbon black, carbon xerogel, carbon nanotubes or graphene) [3]. A mechanism for the plasma reduction of Pt is proposed. It is shown that the size distribution of the particles, their dispersion at the surface, and their quantity in the bulk determined by inductively coupled plasma mass spectrometry (ICP-MS), can be fully controlled by the plasma and preparation parameters.
The Pt nanoparticles synthesized by either method are finally used to fabricate the cathode of a proton exchange membrane fuel cell (PEMFC) using a gas diffusion layer as a substrate. The cell performance, represented by the ratio of the electrochemically active surface area (ECSA) and the catalytic activity, which are comparable to commercial cells, will be discussed in detail.
[1] H.A. Gasteiger et al. In: W. Vielstich, A. Lamm and H.A. Gasteiger (eds.), Handbook of Fuel Cells – Fundamentals, Technology and Applications, Wiley, Chichester (UK), 2003, Vol.3, p. 593.
[2] C. De Vos et al. J. Phys. D: Appl. Phys. (2017), 50, 105206.
[3] D. Merche et al. Plasma Process. Polym. (2016), 13, 91–104.