Response properties of nitrogen dioxide gas sensors with tin oxide decorated carbon nanotube channel fabricated by two-step dielectrophoretic assembly

Masafumi Inaba,Nisarut Phansiri,Masaki Kono,Michihiko Nakano,Takenori Oda,Junya Suehiro

doi:10.1063/5.0008188

Abstract

Gas sensors with carbon nanotubes (CNTs) and tin dioxide (SnO2) nanoparticles for nitrogen dioxide (NO2) detection are fabricated using a two-step dielectrophoretic (DEP) assembly method, and the NO2 gas detection properties are investigated. For the fabrication of the sensor, CNTs assemble between electrodes by a DEP force, followed by SnO2 nanoparticle decoration also by a DEP assembly method, and the assembled CNTs act as high electric field electrodes. The formed CNT/SnO2 gas sensors exhibit a sharp increase in resistance followed by a gradual decrease upon NO2 exposure. pn hetero-junctions are formed between the CNTs and the SnO2 nanoparticles, and the resistance shift of the depletion region in the CNTs at the pn hetero-junction induces the sharp increase in the resistance.

Highlights

Nitrogen dioxide (NO2), which is widely formed in industry and transportation, is one of the major gas species of air pollution
For the second-step DEP assembly, the carbon nanotubes (CNTs) were already assembled between the Cr electrodes, and they acted as electrodes
CNTs were bridged between the parallel electrodes, which corresponded to the situation where CNTs were assembled between Cr electrodes with a 5-μm gap by the DEP assembly method

Summary

Introduction

Nitrogen dioxide (NO2), which is widely formed in industry and transportation, is one of the major gas species of air pollution. SnO2 nanoparticles should be assembled by the DEP method when a high electric field is formed on the CNT surface.

Results

Conclusion