A Review on Zinc Oxide Nanostructures: Doping and Gas Sensing

Abstract

This paper presents a review on synthesis, structure, and growth mechanisms of one-dimensional nanostructures of ZnO. Solution-based method is a potential deposition technique for large-scale production as its advantages; the low cost, the simplicity of experimental set-up, and the low operating temperature. Mist-atomiser technique is one of the solution-based methods in synthesizing optimized ZnO nanostructures. Doping will lead for better properties of ZnO, which result to wide application area. Nanostructured ZnO is important in promising areas of application which devices utilizing nanostructures such as gas sensors and solar cells, since it is fairly easy to fabricate such forms of ZnO nanostructures, which have good charge carrier transport properties and high crystalline quality.

Influence of External Gaseous Environments on the Electrical Properties of ZnO Nanostructures Obtained by a Hydrothermal Method

“…The response of ZnO nanostructure at 200 °C is relatively fast because of the high concentration of H 2 and the small size of hydrogen molecules. The hydrogen ions react with oxygen ions on the ZnO surfaces and may cause desorption of oxygen from active centers and the ZnO lattice [25,29]. This results in a decrease in the potential barriers between nanograins and thus the resistance of the sensor structure is reduced.…”

“…Also the humidity effect on the gas sensing structures has to be taken into account due to its different values under real operating conditions [28]. Many publications emphasized the potential of ZnO nanostructures in gas sensors [8,25,27,29,30]. …”

“…The investigations concerning gas sensors based on ZnO are already well advanced [20,29,36]. Generally, those structures are tested at elevated temperature (from 200 °C even up to 700 °C) [18,36].…”

Sr- and Ni-doping in ZnO nanorods synthesized by a simple wet chemical method as excellent materials for CO and CO2 gas sensing

“…The gas response is defined as the ratio R air /R gas , where R air is the electrical resistance of the sensor in dry air and R gas the resistance at different target gas concentrations. This paper published in RSC Advances 6 (86), 82733-82742 (2016) 5 (0.74 Å) 21 . The (002) peak was used for the calculation of average grain sizes and results for all samples are shown in Table 1.…”

Highly Sensitive Sputtered ZnO:Ga Thin Films Integrated by a Simple Stencil Mask Process on Microsensor Platforms for Sub-ppm Acetaldehyde Detection

“…Zinc oxide has received considerable attention from the scientific community for gas detection. Although ZnO is interesting because of its low cost, non-toxicity, and fast and strong response values, it can be greatly improved by doping [ 39 ]. Ga dopants have many advantages, such as the rather similar radius as compared to that of Zn, the easy substitution of Zn 2+ by Ga 3+ without lattice distortion, and the decrease in the resistivity of the sensor [ 40 ].…”