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

Abstract

By reducing the aqueous mixture of electrostatically modified or functionalized multi-walled carbon nanotubes (f-MWCNT) and palladium (Pd) using sodium borohydride (NaBH4), a nanocomposite was synthesized. The morphology 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 to 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 metal oxide semiconductor (MOS) based sensors in context of reduced size, reduced power consumption and ease of fabrication. The temporal electrical responses of the nanocomposite to methane were measured at RT. It exhibited a response magnitude of ∼19.5–41.71 % with a small variation of ± 2 % towards 0.5–500 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 experimentally observed that an excellent response time (≈ 20 s) and the recovery time (≈ 25 s) for these devices were recorded for methane. The effect of environmental temperature and humidity were also studied on the methane sensor for the analysis of their long-term stability and self-life. The results showed that very small change is observed over a wide of temperature from 25 to 70 °C and that for %Rh from 20 to 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.