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Tin oxide thin films were deposited on alumina substrates at 350°C by spray pyrolysis technique. The films were studied after annealing them in air at different temperatures 550°C, 750°C and 950°C for 30 min. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption spectroscopy technique. The grain size was observed to be increased, ranging from 40 to 56.1 nm, with the increase in annealing temperature. Absorbance spectra were taken to examine the optical properties. The band gap energy was observed to be decreased with the increase in annealing temperature. These films were tested to various gases at different operating temperature ranging from 50°C to 450°C. The Tin Oxide film showed maximum sensitivity to H2S gas. The H2S sensing property of the SnO2 films was investigated with different annealing temperatures of the films and at different concentrations of H2S gas. It was found that the annealing temperature of the film significantly affects the sensitivity of the SnO2 to the H2S gas. The maximum sensitivity was found in case of the film annealed at temperature 950°C at the operating temperature 100°C. The sensitivity was found to be increased by 24% in case of the film annealed at 950°C as compared to the sensitivity of the film annealed at 550°C. The observed response of the film was for gas concentration of 10 ppm for H2S with reasonable sensitivity. The quick response and fast recovery are the main features of this film. The effect of annealing temperature on the structural, microstructural, optical and gas sensing properties of the nanocrystalline tin oxide thin films were studied and discussed. [ABSTRACT FROM AUTHOR]

In this work, SnO thin films were deposited onto alumina substrates at 350°C by spray pyrolysis technique. The films were studied after annealing in air at temperatures 550°C, 750°C and 950°C for 30 min. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption spectroscopy technique. The grain size was observed to increase with the increase in annealing temperature. Absorbance spectra were taken to examine the optical properties and bandgap energy was observed to decrease with the increase in annealing temperature. These films were tested in various gases at different operating temperatures ranging from 50-450°C. The film showed maximum sensitivity to HS gas. The HS sensing properties of the SnO films were investigated with different annealing temperatures and HS gas concentrations. It was found that the annealing temperature significantly affects the sensitivity of the SnO to the HS. The sensitivity was found to be maximum for the film annealed at temperature 950°C at an operating temperature of 100°C. The quick response and fast recovery are the main features of this film. The effect of annealing temperature on the optical, structural, morphological and gas sensing properties of the films were studied and discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of CeO2 nanoparticles (CeO2 NPs) successfully synthesized by sol–gel and hydrothermal methods. It is cost effective and valuable approach. • CeO2 NPs exhibiting superior gas sensitivity and enhanced dye degradation. • CeO2 NPs exhibiting high NH3 gas sensing responses with other tested gases and photocatalytic activity under MB degraded under sunlight. • CeO2 NPs are often exhibit enhanced surface area leading to improve gas sensing and photocatalytic activity performance. • The gas sensing and photocatalytic activity of CeO2 NPs offers a wide range of applications with potential benefits for environmental sustainability, public health. Cerium dioxide (CeO 2) nanoparticles were synthesized through sol–gel and hydrothermal methods, yielding materials with distinct properties. Characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet–visible spectroscopy (UV–Vis), X-ray Diffraction (XRD), Raman spectroscopy, Cyclic Voltammetry (CV), Photoluminescence spectra (PL), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy with Selected Area Electron Diffraction (TEM-SAED) were employed to analyse the synthesized nanoparticles. The FTIR analysis revealed an absorption band at 475 cm−1, while UV–Visible spectroscopy determined band gap energies of 3 eV and 3.16 eV for the sol–gel and hydrothermal methods, respectively. XRD analysis indicated crystalline sizes of 14.57 nm and 17.41 nm for the sol–gel and hydrothermal methods, respectively. Raman spectroscopy demonstrated active peaks at 464 cm−1 for the sol–gel method and 463 cm−1 for the hydrothermal method. Cyclic Voltammetry showcased different oxidation and reduction peaks, while Photoluminescence spectra provided insights into the excitation spectrum of CeO 2 nanoparticles. FESEM and TEM-SAED images revealed nano-sized spherical spongy CeO 2 nanoparticles. Furthermore, the synthesized CeO 2 nanoparticles exhibited promising photocatalytic degradation activity against methyl blue (MB) dye under sunlight irradiation, with degradation efficiencies of 92 % and 82 % for the sol–gel and hydrothermal methods, respectively. Additionally, gas sensing properties for various gases (ethanol, methanol, CO 2 , LPG, H 2 S, and NH 3) were evaluated using domestic gas sensor systems, showing potential applicability across a broad temperature range from 50 °C to 350 °C. [ABSTRACT FROM AUTHOR]