Highly Stable and Sensitive Gas Sensor Based on Single-Walled Carbon Nanotubes Protected by Metal-Oxide Coating Layer

We fabricated a highly stable and sensitive gas sensor based on single-walled carbon nanotubes (SWNTs) protected by metal-oxide coating layer. SWNTs were deliberately decorated with 2-5 nm of oxygen-deficient SiO(x) and AlO(x) by pulsed laser deposition, followed by annealing under Ar/H(2) ambient. Surpassing the as-grown SWNTs, the metal-oxide coated SWNTs showed an excellent sensing stability with a variation of sensor response less than 7-8%. The obtained sensitivity to NO(2) was also improved. Moreover, the relationship between NO(2) concentration and sensor response can be described by the Frumkin-Temkin isotherm. (C) 2009 The Japan Society of Applied Physics