Room temperature selective propanol sensor based on p-TiO2 NP /n-ZnO NS heterojunction interfaces

Room temperature 2-propanol sensing of p-TiO₂ nanoparticles/n-ZnO nanosheets hetero interfaces is presented in this article. p-TiO₂ nanoparticles and n-ZnO nanosheets was synthesized via sol–gel and low cost hydrothermal and methods followed by heat treatment. Structural, morphological, chemical composition and interface quality were characterized though X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Atomic force microscopy (AFM), Energy dispersive spectroscopy (EDS), and current voltage characteristics, respectively. Room temperature sensing mechanism of p-TiO₂ nanoparticles/n-ZnO nanosheets is primarily due to the synergistic effect of p-n hetero interfaces in association with near surface hole accumulation (of p-TiO₂ nanoparticles) facilitates easy oxidation of 2-propanol. 2-propanol sensing performance showed excellent response magnitude of 68 % with response time and recovery time as ∼ 71 s and ∼ 85 s, respectively at room temperature. Selectivity measurement towards 2-propanol with the other interfering species such as ethanol, methanol, acetone, benzene, toluene and xylene showed maximum selectivity window of 60 % (between 2-propanol-xylene) and the least of 11 % (between 2-propanol-ethanol). Constant baseline resistance (∼2.5 MΩ in air and ∼ 7.4MΩ in 2-propanol) and minimum fluctuation in repeatability characteristics (±1.23 %, ±3.65 %, and ± 4.25 % in response magnitude, response time, and recovery time) suggested good reliability of the devices.