Absorption spectral response of nanotextured WO 3 thin films with Pt catalyst towards H 2

Abstract

The gasochromic response of WO 3 nanotextured thin films coated with a 2.5 nm catalytic Pt layer upon exposure to hydrogen (H 2) gas was investigated. The Pt/WO 3 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 H 2 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 H 2 at 100 °C. Films typically had rapid response and recovery, in the range of few seconds. WO 3 thin films were characterized via Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). XRD confirmed the presence of WO 3 crystallites with a preferential miller index orientation of (2 0 0), and SEM investigations revealed that the WO 3 compact thin films were comprised of nanotextured grains.