Nanostructured Indium Oxide Thin Films as a Room Temperature Toluene Sensor

Toluene gas is the most toxic and affects the respiratory system of humans, and thereby, its detection at lower levels is an important task. Herein, we report a room temperature-operatable indium oxide-based chemiresistive gas sensor, which detects 50 ppm toluene vapors. Nanocrystalline indium oxide (In2O3) films were sprayed on a pre-cleaned glass substrate using a cost-effective spray pyrolysis method at different substrate temperatures in the range of 350-500 °C. The X-ray diffraction studies confirmed that the sprayed thin films, which were deposited at different substrate temperatures, exhibit a cubic structure. The preferred orientation was aligned along the (222) orientation. Average crystallite size calculation based on the Scherrer formula indicates that the crystallite size increases with the enhancement of substrate temperature. FESEM analysis showed that the indium oxide thin films possess uniform grain distribution, which persists over the entire substrate. As the substrate temperature is increased, a partial agglomeration in the film morphology was observed. The deposited film's nanostructured nature was confirmed by transmission electron microscopy, and the polycrystalline nature was confirmed from the selected area electron diffraction pattern. Root mean square roughness of the samples was determined from the atomic force microscopy studies. From the Raman spectra, characteristic vibrational modes appeared at 558.61, 802.85, and 1097.18 cm-1 in all the samples, which confirms the cubic structure of indium oxide thin films. Photoluminescence emission spectra have been recorded with an excitation wavelength of 280 nm. The optical band gap was measured using the Tauc plot. The band gap was found to decrease with an increase in the substrate temperature. The gas-sensing performance of indium oxide films sprayed at various substrate temperatures has demonstrated a better response toward 50 ppm toluene gas at room temperature with good stability, and the response and recovery times were determined using a transient response curve.

Designed synthesis of Co-doped sponge-like In2O3 for highly sensitive detection of acetone gas

Materials based on Co-doped sponge-like In₂O₃ with high sensing properties were fabricated for easier detection of acetone gas.

Reducing gas-sensing performance of Ce-doped SnO2 thin films through a cosputtering method

SnO₂ thin films doped with various concentrations of Ce were grown by cosputtering Sn and Ce metallic targets in an Ar/O₂ mixed atmosphere.

Regulable switching from p- to n-type behavior of ordered nanoporous Pt-SnO2 thin films with enhanced room temperature toluene sensing performance

In this work, a nanoporous SnO₂ sensing film is fabricated in situ on a sensing device using a block polymer template and is applied as a chemiresistive gas sensor. The ordered film is capable of detecting 10 ppm toluene at room temperature and shows good stability.

Preparation of reduced graphene oxide/Co3O4 composites and sensing performance to toluene at low temperature

The rGO/Co₃O₄ composite not only exhibits the high response to 5 ppm toluene but also displays excellent selectivity to some of VOCs.

One-pot synthesis of La-doped SnO2 layered nanoarrays with an enhanced gas-sensing performance toward acetone

Acetone-sensing properties were greatly enhanced by La-doped SnO₂ nanoarray with a novel nanostructure of double nanorod layers synthesized by hydrothermal method.

Enhanced gas-sensing performance of SnO2/Nb2O5 hybrid nanowires

An example of enhanced gas sensitivity by the formation of SnO₂/Nb₂O₅ hybrid structure.