Ni2O3-decorated SnO2 particulate films for methane gas sensors

High-performance methane gas sensors were developed from Ni2O3-decorated SnO2 semiconducting films. The SnO2 film was fabricated by the sputter deposition of Sn metal followed by oxidation. Ni nanoparticles were then deposited onto the SnO2 film by the arc discharge deposition of single-wall carbon nanotubes followed by the burning out of carbon nanotubes. The catalytic Ni nanoparticles distributed in the carbon nanotubes were oxidized to Ni2O3. The surface morphology and structural properties were examined by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The methane gas sensing properties were examined at different operation temperatures with SnO2 thickness and Ni2O3 quantity as variables. The synergetic effects induced by the Ni2O3-decoration including enhanced response and lowered operation temperature were observed. We also report very high sensor responses. The sensing mechanism of the hybrid sensor structure was also discussed.