Electrostatically functionalized CVD grown multiwalled carbon nanotube/palladium nanocomposite (MWCNT/Pd) for methane detection at room temperature

By reducing the aqueous mixture of electrostatically modified multi-walled carbon nanotubes (f-MWCNT) and palladium (Pd) using NaBH4, a nanocomposite was synthesized. The syllable structure of the f-MWCNT and f-MWCNT/ Pd nanocomposite was investigated by analytical tools FESEM and TEM respectively. f-MWCNTs matrix reinforced with Pd nanoparticles are utilized for sensing methane with its dilution varying from 0.5-100 ppm in air at room temperature (RT=27°C). The f-MWNT/Pd nanocomposite-based sensor for methane gas show several merits over conventional catalytic beads and MOS based sensors in context of reduced size, reduced power consumption and ease of fabrication. At room temperature, the nanocomposite's temporal electrical responses to methane were measured. It exhibited a response magnitude of ∼20-45.71% with a small variation of ±2% towards 0.5-100 ppm methane. Furthermore, the responses were extremely reversible and repeatable, implying that it may be used to detect methane at ambient temperature. It has also been demonstrated experimentally that an excellent response time (≈ 20 s) and the recovery time (≈ 25 s) for these devices were recorded for methane. The influence of external temperature and humidity on the methane sensor was also investigated in order to assess its long-term stability and self-life. The results showed that very small change is observed over a wide of temperature from 25-70oC and that for %Rh from 20-90%. Therefore, the reported methane sensor absolutely demonstrated long-term stability at ambient conditions and hence, these devices can prove to be ideal for methane leakage detection for practical real time applications. A sensing mechanism by which methane is detected by f-MWCNT/Pd nanocomposite is also elaborately discussed.