(154a) Advanced Heterogeneous Catalysts From Organic Solution Synthesis

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.