Highly Uniform Platinum Icosahedra Made by Hot Injection-Assisted
GRAILS Method
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Abstract
Highly uniform Pt icosahedral nanocrystals
with an edge length
of 8.8 nm were synthesized in nonhydrolytic systems using the hot
injection-assisted GRAILS (gas reducing agent in liquid solution)
method. The results show the key factors for the shape control include
fast nucleation, kinetically controlled growth, and protection from
oxidation by air. The effect of oxygen molecules on the Pt morphology
was experimentally confirmed based on the study of shape evolution
of icosahedral crystals upon exposure to oxygen gas. The Pt icosahedral
catalysts obtained had an area-specific activity of 0.83 mA/cm<sup>2</sup> Pt, four times that of 0.20 mA/cm<sup>2</sup> Pt for typical
Pt/C catalysts, in an oxygen reduction reaction (ORR)