title: Hydrogen sensing properties of protective-layer-coated single-walled carbon nanotubes with palladium nanoparticle decoration.
abstract: Protective-layer-coated single-walled carbon nanotubes (SWNTs) with palladium nanoparticle decoration (Pd-SiO(2)-SWNTs) were fabricated and their sensing properties for hydrogen (H(2)) were investigated. SWNTs were coated with a 3-4 nm thick SiO(2) layer by pulsed laser deposition and subsequently decorated with Pd nanoparticles by electron beam evaporation. Even though the SWNTs were completely surrounded by a protective layer, Pd-SiO(2)-SWNTs responded to H(2) down to a concentration of 1 part per million. Compared with the Pd nanoparticle-decorated SWNTs without a protective layer (Pd-SWNTs), Pd-SiO(2)-SWNTs exhibited highly stable sensor responses with variations of less than 20%; Pd-SWNTs showed a variation of 80%. The density of the Pd-SWNTs significantly decreased after the sensing test, while that of the Pd-SiO(2)-SWNTs with the netlike structure remained unchanged. The hydrogen sensing mechanism of the Pd-SiO(2)-SWNTs was attributed to the chemical gating effect on the SWNTs due to dipole layer formation by hydrogen atoms trapped at the Pd-SiO(2) interface. Moreover, the relationship between H(2) concentration and sensor response can be described by the Langmuir isotherm for dissociative adsorption.
authors.affiliation: College of Nanotechnology, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand.
authors.forename: W
authors.initials: W
authors.lastname: Wongwiriyapan
authors.forename: Y
authors.initials: Y
authors.lastname: Okabayashi
authors.forename: S
authors.initials: S
authors.lastname: Minami
authors.forename: K
authors.initials: K
authors.lastname: Itabashi
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: R
authors.initials: R
authors.lastname: Shimazaki
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Oura
authors.forename: S
authors.initials: S
authors.lastname: Honda
authors.forename: H
authors.initials: H
authors.lastname: Tabata
authors.forename: M
authors.initials: M
authors.lastname: Katayama