AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Fabricating WO3-based Nanostructured Materials for Solid-State NOx Gas Sensors
JULIEN GAURY, George Biskos, Delft University of Technology
Abstract Number: 473 Working Group: Nanoparticles and Materials Synthesis
Abstract Energy production from fossil fuels results into emissions of gaseous species (e.g., CO, SO2, NOx, etc.) that can threaten human health and affect regional and global climate. Sensors for monitoring gaseous emissions from energy conversion processes are therefore very important for controlling their environmental effects. Despite the great efforts in fabricating such sensors, most of them have the disadvantage of being technologically complex and expensive. Methods for producing simple and cost-effective sensors are therefore highly needed.
In this paper we fabricate WO3-based nanostructured materials, using Electrostatic Spray Deposition (ESD), for chemiresistive solid-state NOx gas sensors. In ESD, nanoparticle building blocks are synthesized by atomizing a liquid precursor solution using electrical forces, and are deposited onto heated chip substrates by electrostatic field. By tuning the temperature during deposition, we produce nanostructured thin films having granular and dendritic morphologies. By further annealing of the samples we produce hexagonal WO3 nanowires out of the as-deposited amorphous aggregates. This nanowire structures exhibit a higher surface-to-volume ratio compared to the non-annealed sample, thereby increasing the sensitivity of the sensor. To further enhance the electrical properties and thus the sensitivity of the materials towards NOx species, we also dope our sample with Niobium and Tantalum. The addition of doping species results in the formation of oxygen vacancies within the stoichiometric WO3 layer, thereby creating active sites for NOx adsorption.