Multi-walled carbon nanotubes–cellulose paper for a chemical vapor sensor

This paper reports the multi-walled carbon nanotubes (MWCNTs)–cellulose paper as a chemical vapor sensor. Cellulose solution was prepared by dissolving cotton pulp in LiCl/N,N-dimethylacetamide solution. MWCNTs were covalently grafted to cellulose by reacting imidazolides–MWCNTs with cellulose solution. Using this product, the MWCNTs/cellulose (M/C) paper was fabricated, followed by mechanical stretching to align MWCNTs with cellulose chains. Characteristics of the M/C paper were analyzed in terms of scanning electron microscope images, Young's modulus and electrical resistance. The M/C paper was investigated as a chemical sensor that can detect vaporized analyte molecules, such as, methanol, ethanol, 1-butanol and 1-propanol. Their electrical responses on the sensor were evaluated by not only comparing their relative resistance response (AR) depending on the concentration, but also checking signal reversibility under cyclic exposure of each analyte. Due to sensitive and reversible expansion/contraction of the M/C paper in response to analytes, the M/C paper showed reversible and fast response with the following rank of AR: methanol < ethanol < 1-propanol < 1-butanol. Especially, the linear response to 1-propanol concentration proved that the M/C paper can be a qualified sensor for n-propanol.