Self-Assembly and Characterization of Pt Nanoparticles by Electrochemistry and In-Situ FTIR Reflection Spectroscopy
CHEN Wei，SUN Shi-gang*
State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, Institute of Physical Chemistry, Xiamen University, Xiamen 361005，China
Abstract：Pt nanoparticles (Ptn) were prepared by chemical reduction method. The average dimension of Ptn is about 2.5 nm in diameter determined from TEM studies. The Pt nanoparticles were then self-assembled on massive Au substrate. The process of self-assembly was investigated with Fe(CN)4-／3-6 for redox probe reaction. The result showed that the dithiol assembled on Au surface is inactive for electron transfer. However after assembly of Pt nanoparticles on the dithiol, the Au/SS-Ptn electrode becomes conductive again for electron transfer. The adsorption of CO on the Pt nanoparticles self-assembled on Au substrate in 0.1 mol·L-1 H2SO4 was studied by using in situ FTIR reflection spectroscopy. IR absorption of linear and bridge bonded CO species was observed around 2 030 and 1 845 cm-1 respectively. IR absorption of twin bounded CO adsorbed on the Pt nanoparticles was also observed about 2 100 cm-1. The results illustrated that the IR absorption of CO adsorbed on the Pt nanoparticles has been significantly enhanced. The present study is devoted to revealinｇ the intrinsic properties of self-assembly system of nanoparticles, and is of importance in applications of electrocatalysis as well.
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