Individual hollow and mesoporous aero-graphitic microtube based devices for gas sensing applications

Enthalten in
Applied physics letters 
Volume
110
Issue
26
Article Number
263109
Citation
Applied Physics Letters 26 (110): 263109 (2017-06-26)
Publisher DOI
10.1063/1.4989841
Scopus ID
2-s2.0-85021632795
Publisher
American Institut of Physics
In this work, individual hollow and mesoporous graphitic microtubes were integrated into electronic devices using a FIB/SEM system and were investigated as gas and vapor sensors by applying different bias voltages (in the range of 10 mV-1 V). By increasing the bias voltage, a slight current enhancement is observed, which is mainly attributed to the self-heating effect. A different behavior of ammonia NH3 vapor sensing by increasing the applied bias voltage for hollow and mesoporous microtubes with diameters down to 300 nm is reported. In the case of the hollow microtube, an increase in the response was observed, while a reverse effect has been noticed for the mesoporous microtube. It might be explained on the basis of the higher specific surface area (SSA) of the mesoporous microtube compared to the hollow one. Thus, at room temperature when the surface chemical reaction rate (k) prevails on the gas diffusion rate (DK) the structures with a larger SSA possess a higher response. By increasing the bias voltage, i.e., the overall temperature of the structure, DK becomes a limiting step in the gas response. Therefore, at higher bias voltages the larger pores will facilitate an enhanced gas diffusion, i.e., a higher gas response. The present study demonstrates the importance of the material porosity towards gas sensing applications.
DDC Class
530: Physik
600: Technik
More Funding Information
Funded in parts by the German Research Foundation (DFG-Deutsche Forschungsgemeinschaft) under the schemes FOR 2093, AD 183/17-1 at Kiel University and SFB 986-TP-B1 and SCHU 926/25-1 at TUHH.