Absorption spectral response of nanotextured WO3 thin films with Pt catalyst towards H2

The gasochromic response of WO3 nanotextured thin films coated with a 2.5 nm catalytic Pt layer upon exposure to hydrogen (H-2) gas was investigated. The Pt/WO3 thin films exhibited gasochromic characteristics, when measured in the visible-NIR (400-900 nm) range. The total absorbance in this range increased approximately 15% when exposed to 0.06% H-2 gas in synthetic air. Similarly, a 60% increase was measured to an exposure of 1% H-2 gas in synthetic air. However, this response was reduced by approximately 40% when exposed to the same concentration of H2 gas in air with humidity of 6%. These measurements were conducted over a range of temperatures with extensive analysis preformed at both room temperature and 100 C to ascertain the suitability of the films for low power applications. Despite having a comparatively slow recovery time at room temperature, it was observed that these films were highly sensitive, providing stable and repeatable responses towards low concentrations of H2 at 100 C. Films typically had rapid response and recovery, in the range of few seconds. WO3 thin films were characterized via Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). XRD confirmed the presence of WO3 crystallites with a preferential miller index orientation of (2 0 0), and SEM investigations revealed that the WO3 compact thin films were comprised of nanotextured grains. (c) 2008 Elsevier B.V. All rights reserved.