253371 Advanced Heterogeneous Catalysts From Organic Solution Synthesis

Monday, October 29, 2012: 3:15 PM
317 (Convention Center )
Chao Wang, Materials Science Division, Argonne National Laboratory, Argonne, IL

Advanced Pt-bimetallic Electrocatalysts from Organic Solution Synthesis

Alloy nanoparticles (NPs) have attracted increasing interest due to their superior performance in various catalytic applications.  Particularly Pt alloys with transition metals (PtM with M = Fe, Co, Ni, etc.) have been found to be highly active for the oxygen reduction reaction in fuel cells.  A lot of efforts have been dedicated to the synthesis of Pt-based alloy catalysts, which are usually in the form of PtM NPs dispersed in high surface area carbon matrix.  The approaches mostly include co-precipitation of metal salts in aqueous solution, impregnation of transition metals into Pt/carbon catalyst, and electrodeposition.  In spite of the preparation of various types of alloy catalysts, it yet remains a challenge to synthesize monodisperse and homogeneous Pt-bimetallic catalysts.  Recently we have been able to synthesize high-quality bimetallic alloy nanocatalysts via an organic solvothermal approach.  Control over particle size (Fig. 1), alloy composition and alloy homogeneity has been achieved, which has enabled systematic studies of the effects of these parameters on electrocatalytic activity for the oxygen reduction reaction.  Our studies thus provide clues for the optimal particle sizes and alloy compositions in electrocatalysis.

Figure 1. (a) Schematic illustration of the synthesis of monodisperse and homogeneous Pt3Co NPs with size controlled by the temperature of adding Co precursor. (b-d) TEM images of the obtained 3, 4.5, and 6 nm Pt3Co NPs. (e) shows a representative TEM image of the as-prepared Pt3Co/carbon catalysts by supporting the colloidal Pt3Co NPs on high-surface-area carbon black.


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