Sobia Ashraf tells Journal of Materials Chemistry about her hot paper.

Could you explain the significance of your article to the non-specialist? 
We have demonstrated that using AACVD broadens the range of molecules suitable for use as CVD precursors. XRD, Raman and XPS analysis of the films indicates that there is a correlation between the stoichiometry of the films and the orientation of the crystallites within the film. The films function as gas sensors showing responses comparable to that of commercially available screen-printed sensors upon exposure to trace amounts of ethanol and NO2 in air, but with enhanced speeds of response.

What has motivated you to conduct this work?
AACVD has traditionally been used when conventional atmospheric pressure CVD precursors prove involatile or thermally unstable. However we selected polyoxometalates specifically for use as AACVD precursors.  We were also interested in developing a new technique for gas sensor fabrication. The gas-sensing characteristics of a material are governed by a number of factors including stoichiometry, density/porosity, grain size and thickness. CVD gives direct control over these properties and is directly compatible with silicon microfabrication technology.  

Where do you see this work developing in the future?
We would like to produce doped tungsten oxide films using polyoxometalate precursors and study the effect this has on the microstructure and gas-sensing properties of the resulting films. We have also used polyoxometalates as a route to the deposition of molybdenum oxide films. Depositing vanadium oxide films using polyoxovanadates is another avenue we may explore, further demonstrating the versatility of polyoxometalates as CVD precursors.

Are there any particular challenges facing future research in this area?
There are no major challenges facing future research in this area - other than to try and ensure commercialization of the results.

Sobia Ashraf received an MSc from University College London in 2004. She is currently working for her PhD under the supervision of Professor Ivan Parkin. Her research interests include polyoxometallate synthesis, aerosol assisted CVD using novel precursors, and gas sensing.