Fabrication of a Highly Sensitive Single Aligned TiO₂ and Gold Nanoparticle Embedded TiO₂ Nano-Fiber Gas Sensor

In this research, a single-aligned nanofiber of pure TiO₂ and gold nanoparticle (GNP)-TiO₂ were fabricated using a novel electro-spinning procedure equipped with secondary electrostatic fields on highly sharp triangular and rectangular electrodes provided for gas sensing applications. The sol used for spinning nanofiber consisted of titanium tetraisopropoxide (C₁₂H₂₈O₄Ti), acetic acid (CH₃COOH), ethanol (C₂H₅OH), polyvinylpyrrolidone (PVP), and gold nanoparticle solution. FE-SEM, TEM, and XRD were used to characterize the single nanofiber. In triangular electrodes, the electrostatic voltage for aligning single nanofiber between electrodes depends on the angle tip of the electrode, which was around 1.4-2.1, 2-2.9, and 3.2-4.1 kV for 30°, 45°, and 60°, respectively. However, by changing the shape of the electrodes to rectangular samples and by increasing distance between electrodes from 100 to 200 μm, electro-spinning applied voltage decreased. Response of pure TiO₂ single nanofiber sensor was measured for 30-200 ppb carbon monoxide gas. The triangular sample revealed better response and lower threshold than the rectangular sample. Adding appropriate amounts of GNP decreased the operating temperature and increased the responses. CO concentration threshold for the pure TiO₂ and GNP-TiO₂ triangular samples was about 5 ppb and 700 ppt, respectively.