Electrochemical preparation of molybdenum trioxide thin films: Effect of sintering on electrochromic and electroinsertion properties

Todd M. McEvoy, Keith J. Stevenson, Joseph T. Hupp, Xiaojun Dang

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Molybdenum trioxide (MoO3) thin films prepared by cathodic electrodeposition on indium-tin-oxide coated glass substrates from aqueous peroxo-polymolybdate solutions have been studied as a function of sintering temperature (25-450°C). Cyclic voltammetry, chronopotentiometry, chronoamperometry, and spectroelectrochemical measurements performed with MoO3 thin films in 1 M LiClO4/propylene carbonate demonstrate that the electrochemical behavior (Li+ insertion/extraction and coloration) is strongly dependent upon thermally induced changes in micro-/nanocrystallinity, which directly influence measured Li+ diffusion properties as well as electroinsertion and electrochromic reversibilities. Structural analysis using X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscopy indicate that films heat treated at 100°C or less exist as amorphous oxide-hydrates of molybdenum; whereas film heated to 250°C exist as disordered, mixed-phase materials comprising monoclinic β-MoO3 and orthorhombic α-MoO3. Crystallization to the more thermodynamically stable orthorhombic α-MoO3 occurs at 350°C and above. The mixed-phase material exhibits inhomogeneous electrochemical activity, evidenced by the existence of complicated voltammetric and chronoamperometric responses. The effects of sintering temperature on ion insertion and electrocoloration properties are discussed.

Original languageEnglish
Pages (from-to)4316-4326
Number of pages11
Issue number10
Publication statusPublished - May 13 2003


ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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