We demonstrated the preparation of high-performance toluene (C7H8) gas sensor, by using the Ptmultiwalled
carbon nanotubes (MWCNTs) composite materials. We optimized the size of the Pt
nanoparticles by controlling the predeposited Pt thickness, for obtaining the highest sensing performances.
We have obtained the sensor responses of 3.91 and 5.06, at concentrations of 1 and 5 ppm of C7H8
gas, respectively, at 150 ◦C. We discussed the associated sensing mechanisms and proposed the reasons
why the Pt-functionalization drastically enhanced the sensing behaviors of the Pt-MWCNTs composite
sensors selectively to C7H8 gas.