Response of Palladium and Carbon Nanotube Composite Films to Hydrogen Gas and Behavior of Conductive Carriers

To develop a high-performance hydrogen gas sensor, we fabricated a composite film made of carbon nanotubes (CNTs) and palladium nanoparticles. Carbon nanotubes were spin-coated onto a glass substrate, and subsequently, palladium nanoparticles were sputtered onto this film. The response to hydrogen g...

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Bibliographic Details
Published inMaterials Vol. 13; no. 20; p. 4568
Main Authors Zou, Muxuan, Aono, Yoshinori, Inoue, Shuhei, Matsumura, Yukihiko
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 14.10.2020
MDPI
Subjects
Adsorption
Approximation
Argon
Carbon
carbon nanotube
Carbon nanotubes
Carrier density
Composite materials
DFT
Electron transfer
First principles
Gas mixtures
Gas sensors
Gases
Glass substrates
Hydrogen
Mathematical analysis
Nanoparticles
Palladium
Power supply
resistive sensors
Seebeck effect
sensor
Sensors
Simulation
Spin coating
Summer
thin film
Vacuum chambers
Water chemistry
Winter
Work functions
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Summary:To develop a high-performance hydrogen gas sensor, we fabricated a composite film made of carbon nanotubes (CNTs) and palladium nanoparticles. Carbon nanotubes were spin-coated onto a glass substrate, and subsequently, palladium nanoparticles were sputtered onto this film. The response to hydrogen gas was measured during two seasons (summer and winter) using a vacuum chamber by introducing a hydrogen/argon gas mixture. There was a clear difference in the sensor response despite the temperature difference between summer and winter. In addition, since a clean chamber was used, fewer water molecules acted as a dopant, and the behavior of the CNT changed from p-type to n-type because of the dissociative adsorption of hydrogen. This phenomenon was confirmed as the Seebeck effect. Finally, the work functions of Pd, PdHx, and CNT were calculated by first-principle calculations. As predicted by previous studies, a decrease in work function due to hydrogen adsorption was confirmed; however, the electron transfer to CNT was not appropriate from the perspective of charge neutrality and was found to be localized at the Pd/CNT interface. It seems that the Seebeck effect causes the concentration of conductive carriers to change.
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ISSN:1996-1944
1996-1944
DOI:10.3390/ma13204568