Sprayed Carbon Nanotube Thin Films as Hydrogen Sensors
- PDF / 80,066 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 108 Downloads / 211 Views
0900-O06-15.1
Sprayed Carbon Nanotube Thin Films as Hydrogen Sensors Isabel Sayago1, Eva Terrado2, Manuel Aleixandre1, María del Carmen Horrillo1, Jesús Lozano1, María Jesús Fernández1, Esperanza Lafuente2, Wolfgang K. Maser2, Javier Gutiérrez1, María Teresa Martínez2, Ana M. Benito2 and Edgar Muñoz2,* 1 Laboratorio de Sensores, IFA-CSIC, Serrano 144, 28006 Madrid, Spain 2 Instituto de Carboquímica, CSIC, Miguel Luesma Castán 4, 50018 Zaragoza, Spain
ABSTRACT We report a novel, simple, and inexpensive method for preparing efficient carbon nanotubebased hydrogen sensors. Sensor devices were fabricated by simply spraying single-walled carbon nanotube (SWNT) dispersions on alumina substrates. Pd-functionalization of the employed SWNTs enabled increasing the device sensitivity to hydrogen. The effect of aging, thermal processing, and the employed carrier gases on the sensor performance is here described. The fabricated thin film sensors exhibited good sensitivity to hydrogen at room temperature in reversible and reproducible detection processes.
INTRODUCTION Carbon nanotubes have attracted much scientific interest due to their outstanding structural, mechanical, and physical properties, as well as for their promise for applications as components for nanoelectronics, multifunctional composite materials, electrochemical devices, or field emission devices [1]. Additionally, carbon nanotubes are promising materials to be utilized as components for gas- and chemical sensors because of their high surface area, hollow geometry, and electronic properties. Carbon nanotube-based gas sensors have already been demonstrated: thus, different configurations have successfully been tested, including individual nanotube sensors [2], resistive sensors [3] and chemicapacitors [4] fabricated from carbon nanotubes grown on silicon substrates by chemical vapor deposition, and carbon nanotube assemblies [5] and composite films [6-8] directly deposited on interdigitated electrodes. The fabrication of sensitive hydrogen sensors is a key issue for the development of a new technology based on the use of hydrogen as a clean energy source for fuel cells, since molecular hydrogen is a flammable gas for concentrations higher than 4 %. While molecular hydrogen does not strongly interact with pristine carbon nanotube materials, Pd-functionalized carbon nanotubes can be employed as components of efficient, sensitive hydrogen sensors [9-12]. The enhanced sensitivity to hydrogen is based on the ability of Pd to dissociate hydrogen molecules into atomic hydrogen at room temperature. The atomic hydrogen then dissolves into Pd surfaces decreasing the work function of Pd, leading to electron transfer to the carbon nanotubes, and decreasing the hole-carriers in the nanotubes (that behave like p-type materials due to electron withdrawing by oxygen molecules adsorbed on the nanotube surface [9,13,14]), therefore increasing the sensor resistance [9]. We here show how thin carbon nanotube films fabricated by simply spraying SWNT dispersions on alumina substrates
Data Loading...
