Thursday 21 Mar 2013Title: Synthesis of 1D tungsten oxide and oxynitride nanostructures

Fang Xu - University of Exeter

HAR/170 (3D Visualisation Suite) 14:00-15:00

Nanostructured tungsten oxides, WOx (2<=x<=3), are very promising for applications as catalysts, gas sensors, electric field emitters, and in electro-chromic and electrochemical devices. As an analogy to WOx, nanostructured WNx are very useful as a photocatalyst for water decomposition, effective barriers in semiconductor devices, cathode catalyst for fuel cells and catalyst for NO dissociation etc. Accordingly, a diverse technique has been attempted towards the synthesis of these materials, in particular, their 1-dimensional form such as nanorods/nanowires which may possess excellent properties attributed to their large aspect ratio.

In our work, studies have be focused on the production of 1D WOx nanostructures using simple, effective methods, with better quality, and on the investigation into the growth mechanism to gain a deeper understanding and to achieve materials with desired morphology, and pattern. In this talk, the creation of patterned growth of both 1-D WOx and WOxNy nanorods using a simple oxidation and ammonisation process at high temperature on an Au-masked W substrate will be introduced first, with possible growth mechanism proposed as well [1]. This method has opened new route for nanodevice construction. In addition, systematic studies on preparation of WOx nanowires will be discussed, including the morphology dependence on precursor concentration, reaction time as well as different solvent. Ultra-fine WOx nanowires with a new record surface area have been generated, which would be fundamentally essential for applications such as gas sensor [2] and electro-chromic device.

References:
1. Xu, F., Zhu Y.Q. et al., Patterned growth of tungsten oxide and tungsten oxynitride nanorods from Au-coated W foil. Nanoscale, 2012. 4(22): p. 7031-7037.
2. Y. M. Zhao and Y.Q. Zhu, Room temperature ammonia sensing properties of W18O49 nanowires. Sens. Actuators, B, 2009. 137(1): p. 27-31.

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