An Efficient Hydrogen Sensor Device Based on TiO2 Homojunctions

In this work, TiO2 semiconductor junctions were investigated to improve the performance of hydrogen sensors. To develop TiO2 homojunction with tetragonal (anatase), tetragonal-orthorhombic, and tetragonal-tetragonal (anatase-rutile) structures, we used a simple sol-gel method followed by heat treatment at different temperatures such as 400 °C, 600 °C, and 800 °C. The samples were characterized using X-ray diffraction (XRD) and UV-visible diffuse reflectance spectroscopy (UV-visible DRS) and used to develop efficient conductivity sensors for H2 monitoring. The obtained results showed that the tetragonal orthorhombic TiO2 homojunction obtained at 600 °C annealing temperature exhibited good H2 performance (sensor response Ra/Rg of about 5.3 at 5000 ppm and fast response/recovery of 4 s and 14 s, respectively).