Shao-Lin Zhang

NO Sensing Characteristics of ZnO Nanorod Prepared by Ultrasound Radiation Method

ZnO nanorod gas sensors were prepared by an ultrasound radiation method and their gas sensing properties were investigated for NO gas. For this procedure, 0.01, 0.005 and 0.001M of zinc nitrate hydrate [] and hexamethyleneteramine [] aqueous solutions were prepared and then the solution was irradiated with high intensity ultrasound for 1 h. The lengths of ZnO nanorods ranged from 200 nm to 500 nm with diameters ranging from 40 nm to 80 nm. The size of the ZnO nanorods could be controlled by the concentration of solution. The sensing characteristics of these nanostructures were investigated for three kinds of sensor. The properties of the sensors were influenced by the morphology of the nanorods.

Preparation of g-C3N4/Graphene Composite for Detecting NO2 at Room Temperature

Graphitic carbon nitride (g-C3N4) nanosheets were exfoliated from bulk g-C3N4 and utilized to improve the sensing performance of a pure graphene sensor for the first time. The role of hydrochloric acid treatment on the exfoliation result was carefully examined. The exfoliated products were characterized by X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-Vis spectroscopy. The exfoliated g-C3N4 nanosheets exhibited a uniform thickness of about 3–5 nm and a lateral size of about 1–2 µm. A g-C3N4/graphene nanocomposite was prepared via a self-assembly process and was demonstrated to be a promising sensing material for detecting nitrogen dioxide gas at room temperature. The nanocomposite sensor exhibited better recovery as well as two-times the response compared to pure graphene sensor. The detailed sensing mechanism was then proposed.

Controlled Synthesis of ZnO Nanostructures for Sub-ppm-Level VOC Detection

Various ZnO nanostructures, including nanoparticles, nanorods, nanotubes, and nanorings, were synthesized via a controlled synthesis by a facile sonochemical method combined with a chemical etching process. The morphology and structure of the fabricated nanomaterials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The sensing properties of different ZnO nanostructures toward volatile organic compounds gases at sub-ppm levels were investigated. The differences in the sensing responses of various nanostructures were compared, and reasonable mechanisms are proposed here.

Selective Growth of ZnO Nanorods and Its Gas Sensor Application

The facile sonochemical method has been used to selectively grow a ZnO nanorods sensing layer directly on an alumina substrate. The growth region of the ZnO nanorods array is precisely controlled by a pre-coated Pt/Zn seed layer on alumina substrate. No growth of ZnO nanostructure is found on the substrate without seed layer. The grown ZnO nanorods are well aligned and densely packed, with wurtzite crystal structure and flat hexagonal tip. The sensing properties of the obtained ZnO nanorods sensing layer to three kinds of toxic gases ( NH3, CO, and CH4) have been investigated. The sensing observation revealed that the selectively grown ZnO nanorods demonstrated good response, repeatability, and excellent linearity toward toxic gases. This result indicates that selective growth of ZnO nanorods directly on sensor substrate is an accessible and advantageous method for sensor fabrication.

First-principle study of the structural, electronic, and optical properties of SiC nanowires

We preform first-principle calculations for the geometric, electronic structures and optical properties of SiC nanowires (NWs). The dielectric functions dominated by electronic interband transitions are investigated in terms of the calculated optical response functions. The calculated results reveal that the SiC NW is an indirect band-gap semiconductor material except at a minimum SiC NW (n = 12) diameter, showing that the NW (n = 12) is metallic. Charge density indicates that the Si–C bond of SiC NW has mixed ionic and covalent characteristics: the covalent character is stronger than the ionic character, and shows strong s–p hybrid orbit characteristics. Moreover, the band gap increases as the SiC NW diameter increases. This shows a significant quantum size and surface effect. The optical properties indicate that the obvious dielectric absorption peaks shift towards the high energy, and that there is a blue shift phenomenon in the ultraviolet region. These results show that SiC NW is a promising optoelectronic material for the potential applications in ultraviolet photoelectron devices.

Controlled Synthesis of ZnO Nanostructures for ppb‐level VOC Detection

In the present study, we deal with the controlled synthesis of ZnO nanoparticles (ZNPs), nanorods (ZNRDs), nanotubes (ZNTs), and nanorings (ZNRs) by combining sonochemical process and etching treatment. Gas sensors based on these fancy nanostructures are fabricated and the gas sensing properties towards VOC gases are investigated. The investigation demonstrates that the ZnO nanostructures based sensors have great potential for ppb‐level VOC detection.