Highly sensitive H2S gas sensors based on CuO-coated ZnSnO3 nanorods synthesized by thermal evaporation

ZnSnO3 one-dimensional (1D) nanostrutures were synthesized by thermal evaporation. The morphology, crystal structure and sensing properties of the CuO-coated ZnSnO3 nanostructures to H2S gas at 100 °C were examined. Transmission electron microscopy and X-ray diffraction revealed both the ZnSnO3 nanorods and CuO nanoparticles to be single crystals. The diameters of the CuO nanoparticles on the nanorods ranged from a few to a few tens of nanometers. The gas sensors fabricated from multiple networked CuO-coated ZnSnO3 nanorods exhibited enhanced electrical responses to H2S gas compared to the uncoated ZnSnO3 nanorod sensors, showing 61.7-, 49.9-, and 31.3-fold improvement at H2S concentrations of 25, 50, and 100 ppm, respectively. The response time of the nanorod sensor to H2S gas was reduced by the CuO coating but the recovery time was similar. The mechanism for the enhanced H2S gas sensing properties of ZnSnO3 nanorods by the CuO coating is discussed.