Gas Sensing Properties of Methane Based on Al2O3-Doped Multi-Walled Carbon Nanotubes

This paper reports, the methane gas sensing properties based on Al2O3-doped multi-walled carbon nanotubes (MWCNTs). The MWNTs were prepared by low pressure chemical vapor deposition (LPCVD) process. The gamma-Al2O3/MWNTs composite was prepared by mixing different ratios of MWNTs and Al2O3 powder at particular reaction conditions. The prepared composite was used as effective material to fabricate high efficient methane gas sensor with micro-cantilever structure. The observed gas sensing results revealed that the incorporation of MWNTs significantly improved the sensitivity and response time of the newly fabricated methane sensor compared with pure Al2O3. When the methane gas concentration was 1.0%, the sensitivity of the improved sensor was reached to 14.0 mv, with a good linear relationship. The designed new sensor has a fast response to methane, with a 90% response in 9 s and a recovery time of 8 s. The fabricated sensor exhibited high selectivity towards methane gas in presence of other common interfering gases. Thus, it can be concluded that the sensing performance of a catalytic combustion sensor can be enhanced by doping MWNTs into gamma-Al2O3.