Department of Chemistry, SUNY-Potsdam                                          Slide 1 2 3 4 5 6 7 8 9 10

Presented at:                                                                    <<< >>>

8-th Solid State Chemistry Conference                  

Bratislava, SLOVAKIA, July 6-11, 2008


    Sponsored by IUPAC


 Symposium on Layered Compounds, Clathrates and Intercalates

"Electrochemically modulated intercalation and reduction processes of nanostructured WO3 films",

M. Hepel, H. Redmond,

Department of Chemistry, State University of New York at Potsdam, Potsdam, NY


Electrochromic properties and optical density modulation in WO3 films have been studied to elucidate the mechanism of reversible ion intercalation and formation of color centers. The intercalation and electrostatic attachment of inorganic cations and alkyl ammonium cations to WO3 nanoparticles have been investigated using Electrochemical Quartz Crystal Nanobalance (EQCN) and spectroscopic techniques. Strong dependence of the cation ingress on the degree of cation hydration in aqueous solutions has been found. The competition of metal cation intercalation with the uptake of hydronium ions by WO3 films has been observed. The limited mass increases for some cations have been attributed to local water dissociation and hydronium ion uptake. These processes result in pH increase and WO3 reduction, the strongest effect being observed in the presence of alkyl ammonium cations. Improvements in the electrooptic switching performance of WO3 films have been achieved by shortening the solid-state diffusion paths and nanostructured film design.

Graphical Abstract: Large surfactant cation Et4N+ can not intercalate into the electrochromic WO3 cage structure, whereas small cations (Li+, H+) intercalate reversibly causing strong optical absorption due to the formation of polarons and photoelectrons in the conduction band.


Student/Faculty Research                                              Department of Chemistry