Room temperature gas sensors based on carboxyl and thiol functionalized carbon nanotubes buckypapers

•Gas sensors were fabricated using carboxyl and thiol functionalized CNTs buckypapers.•The chemical reactivity of nanotubes was improved significantly at room temperature.•The sensor response of thiolated buckypaper showed better sensitivity under CO and CH4 gases.•The maximum sensitivity observed for 20 ppm CO was 4.78% on thiolated CNTs buckypapers.

In this paper, we report the carbon monoxide (CO) and methane (CH4) gas detection using carboxyl (COOH) and thiol (SH) functionalized carbon nanotubes buckypapers as active material. We observed that the chemical reactivity of nanotubes had shown to improve considerably by functionalizing the sidewalls with specific functional groups at room temperature. Buckypapers were formed by using “4,4′ diaminobenzophenone” in functionalized carbon nanotubes via chemical route. A comparative study is presented for different types of buckypapers by varying the concentration of cross-linker ratio to nanotubes. The maximum sensitivity observed for 20 ppm CO was 4.78% and for 400 ppm CH4 was 2.08% on thiolated CNTs buckypapers. It was also observed that the carboxylic functionalized buckypapers showed decrease in resistance and thiolated buckypapers showed increase in resistance upon exposure to CO gas while carboxylic and thiolated buckypapers showed increase in resistance upon exposure to CH4 gas. Further investigations showed that by increasing the cross-linker concentration to CNTs, thiolated buckypapers exhibited more sensitive to reactive gases.

Graphical abstractChemical reactivity of nanotubes had shown to improve considerably by functionalizing the sidewalls with specific functional groups at room temperature.Figure optionsDownload full-size imageDownload as PowerPoint slide