Super response and selectivity to H2S at room temperature based on CuO nanomaterials prepared by seed-induced hydrothermal growth

Sea anemone-like CuO nanoarrays (SACNAs) are grown on alumina substrates with Ag–Pd interdigital electrodes by seed-induced hydrothermal method with different growth times. The SACNAs composed of CuO nanotentacles show excellent gas-sensing performance at room temperature of 25 °C mainly due to the diameter of nanotentacles close to the Debye length of CuO. Besides, CuO nanoarrays can maximize the adsorption of the gas molecules on the surface area, and further their diffusion between CuO nanotentacles based on the structure of the cross-linked clusters, which could be beneficial for gas-sensing performance. Moreover, the adequate point-to-point contacts between CuO nanotentacles build abundant effective electrical conducting paths for the sensing reactions. A high response up to 24.08 was achieved at as low as 5 ppb H2S with an ultra-low detection limit of 1.52 ppb. In contrast, there are negligible responses to other gases such as ethanol, methanol, acetone and so on, even at very high concentrations (200 ppm). The sensor based on SACNAs indicates a remarkable response to extremely low concentrations of H2S, as well as ultra-high selectivity, excellent repeatability, and long-term stability at 25 °C. The response of the sensor is affected by variations in operating temperature and humidity.