Methane sensor based on nanocomposite of palladium/multi-walled carbon nanotubes grafted with 1,6-hexanediamine

Palladium nanoparticles (PdNPs) were electrolessly deposited on 1,6-hexanediamine grafted multi-walled carbon nanotubes (MWCNTs) to form nanocomposite which was then characterized by scanning electron microscopy, proton nuclear magnetic resonance spectroscopy, and infrared spectroscopy. First, the electrocatalytic activity of MWCNT/PdNPs for methane (CH 4 ) on a gold electrode in 0.50 M H 2 SO 4 was studied by cyclic voltammetry and the results demonstrated that MWCNT/PdNPs could be employed to oxidize CH 4. A simple CH 4 sensor was then fabricated by depositing the MWCNT/PdNPs nanocomposite onto an indium tin oxide substrate. The effects of carrier gas, amount of nanocomposite and temperature on the response of the sensor were investigated in detail. The sensor exhibits good sensitivity and selectivity to CH 4 in dry air at ambient conditions. It showed linear response to CH 4 at 0–16% v/v with a detection limit of 0.167% v/v (signal/noise = 3). The response and recovery times were less than 35 and 12 s, respectively. Common gases such as N 2, CO and CO 2 showed no interference but H 2 and NH 3 displayed slight interference to the sensor.