ZnO Nanorods Grown on ZnO Sol–Gel Seed Films: Characteristics and Optical Gas-Sensing Properties

ZnO sol–gel films, with and without embedded Pt nanoparticles, were used as seeding layers for the hydrothermal growth of ZnO nanorods. The morphology of the nanorods was controlled by adjusting the chemistry and processing, yielding samples with high transparencies and exposed surface areas. The prepared samples were assessed for performance as optical gas sensors in terms of absorbance variation and response time and these data were correlated with the structural properties. The nanorods grown on ZnO films containing Pt nanoparticles showed excellent H₂-sensing properties owing to the high exposed surface areas of the ZnO nanorods and to the catalytic effect the underlying Pt nanoparticles.