Surface acoustic wave based H2S gas sensors incorporating sensitive layers of single wall carbon nanotubes decorated with Cu nanoparticles

This paper presents a surface acoustic wave (SAW) based H2S gas sensor with excellent selectivity and recovery/response time developed using single wall carbon nanotube decorated with copper nanoparticles (Cu NP-SWCNT). A thin film of Cu NP-SWCNT was deposited onto a lithium niobate (LiNbO3) piezoelectric substrate via a drop-casting technique. Sensing of H2S gas was carried out by measuring acoustoelectric perturbation of SAWs traveling along the LiNbO3 piezoelectric substrate and Cu NP-SWCNT sensing layer. H2S gas of concentrations as small as 5 ppm could be readily measured. The effect of temperature on the SAW sensor response was also investigated for a range of temperatures from 70 to 200 °C. The optimum operating temperature was 175 °C, in which, a relatively rapid response (7 s) and recovery time (9 s) was recorded. The selectivity of the proposed Cu NP-SWCNT gas sensor was examined by assessing the sensor response upon exposure to hydrogen, acetone, ethanol, and H2S gas species in air background and a large selectivity toward H2S gas was observed.