A Wide Range Conductometric pH Sensor Made With Titanium Dioxide/Multiwall Carbon Nanotube/Cellulose Hybrid Nanocomposite

Abstract

We report the fabrication and characterization of a pH sensor made with titanium dioxide (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )/multiwall carbon nanotube (MWCNT)/cellulose hybrid nanocomposite. The TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -coated MWCNTs are synthesized by hydrothermal process. The X-ray diffraction and Raman spectra observations show that high anatase crystalline TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanoparticles are well formed on the surface of MWCNTs. After blending the TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /MWCNTs with cellulose solution, the TiO/MWCNT/cellulose hybrid nanocomposite is made and used for the pH sensor. This nanocomposite pH sensor exhibits two linear regions in its conductance between pH 1 and 12. Large surface area of the hybrid nanocomposite increases adsorption sites of ions so as to increase the pH sensitivity as well as sensing range. The long-term stability test and reusable test demonstrate that this hybrid nanocomposite pH sensor is useful for many practical applications. The pH sensing mechanism of this hybrid nanocomposite pH sensor is also discussed in this paper.