Humidity Sensing Behavior of Endohedral Li-Doped and Undoped SWCNT/SDBS Composite Films

Author(s)

Mueller, Christian ^{[1, 2]} ; Al-Hamry, Ammar ^[2] ; Kanoun, Olfa ^[2] ; Rahaman, Mahfujur ^[3] ; Zahn, Dietrich R. T. ^[3] ; Matsubara, Elaine Yoshiko ^{[4, 5]} ; Rosolen, Jose Mauricio ^{[4, 5]}

Affiliation

^[1] Univ Fed Santa Catarina, Dept Fis, BR-88040900 Florianopolis, SC - Brazil

^[2] Tech Univ Chemnitz, Measurement & Sensor Technol, D-09107 Chemnitz - Germany

^[3] Tech Univ Chemnitz, Semicond Phys, D-09107 Chemnitz - Germany

^[4] Univ Sao Paulo, Fac Filosofia Ciencias, BR-14040901 Ribeirao Preto - Brazil

^[5] Univ Sao Paulo, Letras Ribeirao Preto Dept, BR-14040901 Ribeirao Preto - Brazil

• Document type: Journal article
• Source: SENSORS; v. 19, n. 1 JAN 1 2019.
• Web of Science Citations: 1

Abstract

We have investigated single-walled carbon nanotube (SWCNT) networks wrapped with the cationic surfactant sodium dodecyl-benzenesulfonate (SBDS) as promising candidates for water detection. This is the first time that the humidity behavior of endohedral Li-doped (Li@) and undoped SWCNTs/SDBS has been shown. We identified a strong and almost monotonic decrease in resistance as humidity increased from 11 to 97%. Sensitivities varied between -3 and 65% in the entire humidity range. Electrical characterization, Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM) analysis revealed that a combination of the electron donor behavior of the water molecules with Poole-Frenkel conduction accounted for the resistive humidity response in the Li@SWCNT/SDBS and undoped SWCNT/SDBS networks. We found that Li@SWCNTs boosted the semiconducting character in mixtures of metallic/semiconducting SWCNT beams. Moreover, electrical characterization of the sensor suggested that endohedral Li doping produced SWCNT beams with high concentration of semiconducting tubes. We also investigated how frequency influenced film humidity sensing behavior and how this behavior of SWCNT/SDBS films depended on temperature from 20 to 80 degrees C. The present results will certainly aid design and optimization of SWCNT films with different dopants for humidity or gas sensing in general. (AU)

• FAPESP's process: 17/04759-2 - Free-binder electrodes for storage/conversion energy
• Grantee: Jose Mauricio Rosolen
• Support Opportunities: Regular Research Grants