Gas-sensing properties of multi-walled carbon-nanotube sheet coated with NiO

A binary, nanostructured carbon-nanotube (CNT) sheet coated with nickel oxide (NiO) acting as gas sensor was fabricated for the utilization as hydrogen (H2) sensor. Thermal annealing was conducted to improve the sensing ability of the sensor at room temperature. In order to investigate the effect of the surface area of the sensing material, NiO particles of various sizes were deposited onto CNT sheets by electrodeposition, which is a simple method for binary composites. We found a much higher sensitivity at room temperature after thermal annealing. Moreover, the size of the NiO particles significantly affects the sensitivity of the sensor.