Pham Van Tong

Effective decoration of Pd nanoparticles on the surface of SnO2 nanowires for enhancement of CO gas-sensing performance

Decoration of noble metal nanoparticles (NPs) on the surface of semiconducting metal oxide nanowires (NWs) to enhance material characteristics, functionalization, and sensing abilities has attracted increasing interests from researchers worldwide. In this study, we introduce an effective method for the decoration of Pd NPs on the surface of SnO2 NWs to enhance CO gas-sensing performance. Single-crystal SnO2 NWs were fabricated by chemical vapor deposition, whereas Pd NPs were decorated on the surface of SnO2 NWs by in situ reduction of the Pd complex at room temperature without using any linker or reduction agent excepting the copolymer P123. The materials were characterized by advanced techniques, such as high-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The Pd NPs were effectively decorated on the surface of SnO2 NWs. As an example, the CO sensing characteristics of SnO2 NWs decorated with Pd NPs were investigated at different temperatures. Results revealed that the gas sensor exhibited excellent sensing performance to CO at low concentration (1-25ppm) with ultrafast response-recovery time (in seconds), high responsivity, good stability, and reproducibility.

Nanoporous ZnO nanostructure synthesis by a facile method for superior sensitivity ethanol sensor applications

Nanoporous ZnO nanostructures were prepared by simple thermal decomposition of plate-like hydrozincite for gas sensor applications. The plate-like hydrozincite obtained through room temperature precipitation had a diameter of 100 nm and a thickness of about 10 nm. After thermal decomposition, nanoporous ZnO nanoparticles on average 30 nm (16.12 nm in crystalline size) in diameter were obtained. Gas-sensing measurements demonstrated that the nanoporous ZnO nanostructures are promising for superior sensitivity ethanol monitoring in lung cancer diagnosis.

Micro-wheels composed of self-assembled tungsten oxide nanorods for highly sensitive detection of low level toxic chlorine gas

Micro-wheels about 7 μm average diameter and 2.5 μm thick were formed by the self-assembly of tungsten oxide nanorods about 1.5 μm long and 10 nm in diameter. The micro-wheels were hydrothermally synthesized for the ppt level monitoring of highly toxic chlorine (Cl2) gas. The gas sensor based on the fabricated micro-wheels showed excellent performance within a wide range of Cl2 concentrations (100 ppb to 500 ppb), having a high response of ∼10- to 25-fold. This sensor also had an ultra-low detection limit of ∼18 ppt, which was significantly lower than its permissive environmental concentration. In addition, the transient stability of the sensor even after five cycles of switching on/off from air-to-gas demonstrated effective reusability of the device.