Browsing by Advisor Chu, Manh Hung
Showing results [1 - 5] / 5
The design of hetero-nanojunctions can greatly amplify the gas-sensing performance of conventional metal oxide gas sensors. In this study, the composite nanofibers (NFs) of ZnO–SnO2 internal heterojunctions (HJs) and the mixed NFs of ZnO/SnO2 external HJs were realized by using the electrospinning technique. Then, the gas-sensing characteristics of the as-synthesized NFs toward H2S and NO2 gases were systematically investigated and compared. The effects of the internal and external nanojunctions of the hetero-NF-based gas sensors were also explored. Results showed that the ZnO–SnO2 composite NFs demonstrate a higher response than those of the ZnO/SnO2 mixed NFs, as well as bare ZnO an... |
SnO2 nanowires (NWs) are used in gas sensors, but their response to highly toxic gas H2S is low. Thus, their performance toward the effective detection of low-level H2S in air should be improved for environmental-pollution control and monitoring. Herein, Ag2O nanoparticle decorated SnO2 NWs were prepared by a simple on-chip growth and subsequent dip-coating method. The amount of decorated Ag2O nanoparticles on the surface of SnO2 NWs was modified by changing the concentration of AgNO3 solution and/or dipping times. Gas-sensing measurements were conducted at various working temperatures (200–400 °C) toward different H2S concentrations ranging within 0.1–1 ppm. The selectivity of Ag2O-d... |
The selective detection and classification of NH3 and H2S gases with H2S gas interference based on conventional SnO2 thin film sensors is still the main problem. In this work, three layers of SnO2/Pt/WO3 nanofilms with different WO3 thicknesses (50, 80, 140, and 260 nm) were fabricated using the sputtering technique. The WO3 top layer were used as a gas filter to further improve the selectivity of sensors. The effect of WO3 thickness on the (NH3, H2, and H2S) gas-sensing properties of the sensors was investigated. At the optimal WO3 thickness of 140 nm, the gas responses of SnO2/Pt/WO3 sensors toward NH3 and H2 gases were slightly lower than those of Pt/SnO2 sensor film, and the gas r... |
The enhancement of the H2S gas-sensing performance of SnO2 nanowires is vital for practical application. In this study, H2S gas sensors based on WO3-coated SnO2 nanowires were fabricated through a two-step process, namely, the chemical vapor deposition of SnO2 nanowires and then coating with WO3 by sputtering method. The morphology and crystal structures of the SnO2 nanowires coated with WO3 were investigated by field-emission scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The H2S gas-sensing properties of the fabricated sensors were tested at temperatures of 150–250 °C. The SnO2 nanowires coated with 5 nm WO3 showed the best ... |
A unique combination of high response and fast response-recovery is still a challenge in the development of room-temperature gas sensors. Herein, we demonstrated the on-chip growth of nanojunction-networked SnO2 NW sensors to work under UV-radiation at room temperature. The morphological, compositional, and structural properties of synthesized SnO2 nanowires were examined using field emission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy, respectively. The results presented the SnO2 NWs with smooth surfaces were entangled between the Pt electrode. Besides, the internal properties showed the SnO2 NWs were cr... |
