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Anomalous IR properties of nanostructured films created by square wave potential on an array of Pt microelectrodes: an in situ microscope FTIRS study of CO adsorption.

Authors
  • Chen, You-Jiang
  • Sun, Shi-Gang
  • Chen, Sheng-Pei
  • Li, Jun-Tao
  • Gong, Hui
Type
Published Article
Journal
Langmuir : the ACS journal of surfaces and colloids
Publication Date
Nov 09, 2004
Volume
20
Issue
23
Pages
9920–9925
Identifiers
PMID: 15518475
Source
Medline
License
Unknown

Abstract

Thin films of different nanostructures on an array of nine Pt microelectrodes were prepared by applying a square wave potential treatment for different times (tau). It has been measured from the cyclic voltammetric studies that the relative surface roughness of the films was increased slightly and reached a maximal value of about 2.5. SEM studies demonstrated that with the increase of tau, the growth of island-shaped Pt crystallites on the films led to the formation of plumelike crystallites that can reach about 2-3.5 microm in length when tau exceeded 70 min. In situ microscope FTIR reflection spectroscopic studies illuminated that CO adsorbed on the array yielded different anomalous IR features. With the increase of tau, the direction of the CO L band (linearly bonded CO) was transformed from the negative-going direction (normal IR adsorption) to bipolar (Fano-like spectral line shape) and finally to the positive-going direction (abnormal IR adsorption). The intensity of the CO L band was enhanced significantly and a maximal enhancement factor of about 33 was measured when tau was 40 min; the center of the CO L band and the Stark tuning rate also showed regular changes. This study demonstrated that specific nanostructures of Pt thin films can be prepared through a square wave potential treatment for different times and revealed the intrinsic relationship between anomalous IR properties and surface nanostructures of the thin films.

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