Effect of annealing temperature for structural, electrical, and ammonia sensing properties of pristine ZnO and ZnO/SiO2 nanoparticles

Pitchanunt Chaiyo, Kewalin Dokden, Orathai Thumthan, Supon Sumran — Tue, 30 Apr 2024 00:00:00 +0700

The main objective of this research was to study the electrical and gas-sensing properties of Zinc oxide (ZnO) nanoparticles. The samples were divided into two conditions in the preparation process. In the first condition, ZnO powder was annealed at temperatures of 650, 700, and 750 ^๐C for 2 h, while the second condition involved mixing ZnO powder with SiO₂ powder and annealing at temperatures of 650, 700 and 750 ^๐C for 2 h. The characteristics of the prepared samples were studied by scanning electron microscopy (SEM) and the X-ray diffraction technique (XRD). The SEM images showed the agglomeration of the particles with micron-sized diameters. In addition, the XRD patterns of all samples exhibited the hexagonal structure of ZnO. Assessment of the electrical properties of the samples was carried out by forward bias from 0 – 15 V and reverse bias from 0 V to -15 V. The I – V characteristic curves showed diode-like rectifying behavior.The gas-sensing property of the samples was investigated by using ammonia gas, and ZnO nanoparticles annealed at 750 ºC for 2 h were found to have the highest sensitivity.

Oxygen plasma treatment WO3 nanorods for Improvement H2S gas sensing

Chaiyan Oros; Phusit Sangpradub, Preeyanut Daunglaor, Thita Yodsawad — Tue, 30 Apr 2024 00:00:00 +0700

Herein, the oxygen (O₂) plasma has been used to post-treat tungsten oxide (WO₃) nanorods to improve the sensing performance of the H₂S gas sensor. The reactive DC magnetron sputtering process with the glancing-angle deposition (GLAD) technique was used to prepare the WO₃ nanorods. After deposition, the WO₃ nanorod thin films were treated with O₂ plasma at different treatment power from 100 – 200 W. The physical structure of as-deposition and treated WO₃ nanorod thin films was investigated crystal structure and morphology by grazing incident X-ray diffraction (GIXRD), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscope (HRTEM). The result indicated that the WO₃ nanorod structure transformed to the monoclinic polycrystalline phase. FE-SEM and HRTEM observed slight changes in the shape of the WO₃ nanorods. The H₂S sensing properties were measured at 10 ppm at 150 – 350°C operating temperatures. At an operating temperature of 200 °C, the response to H₂S of O₂ plasma treated WO₃ nanorods is increased by a factor of 5 – 15, and the maximum response to H₂S is 15. The results showed that the O₂ plasma treatment process improved the sensing response of the WO3 nanorods.

Journal of Materials Science and Applied Energy

Effect of annealing temperature for structural, electrical, and ammonia sensing properties of pristine ZnO and ZnO/SiO2 nanoparticles

Oxygen plasma treatment WO3 nanorods for Improvement H2S gas sensing