An investigation into the influence of zinc precursor on the microstructural, photoluminescence, and gas-sensing properties of ZnO nanoparticles (original) (raw)

Ozone sensing properties of ZnO nanostructures grown by the aqueous chemical growth technique

Sensors and Actuators B: Chemical, 2007

ZnO nanostructures were deposited on glass substrates by the aqueous chemical growth technique at mild temperatures (95 • C). In general, flowerlike nanostructures are formed, their morphology and dimensions depending on deposition time. Under ultraviolet irradiation and subsequent exposure to ozone atmosphere, the ZnO samples show electrical current changes of three up to six orders of magnitude at room temperature, depending on surface morphology, substrate coverage and average thickness. Samples deposited for 5 h exhibit the highest ozone sensor response, i.e. 10 6 , due to their high surface-to-volume ratio. It is concluded that the ZnO nanostructured samples grown by aqueous chemical growth at low temperatures are promising candidates for semiconductor room temperature ozone sensors.

An easy method of preparing ozone gas sensors based on ZnO nanorods

RSC Adv., 2015

One-dimensional (1D) ZnO nanorod-like structures were successfully grown via a hydrothermal method to be used as an ozone gas sensor. X-ray diffraction measurements (XRD) and field-emission scanning electron microscopy (FE-SEM) analysis revealed a preferential growth of the nanorod-like structures along the [002] direction. Electrical resistance measurements indicated a good sensitivity to different ozone concentrations (0.06-1.19 ppm) as well as long-term stability over a 6 month period at 250 C. In addition, it was observed that the nanorods had a good sensitivity to ozone at room temperature when the sensor was exposed to UV illumination. This study provides an easy and efficient way to obtain 1-D ZnO nanorods exhibiting remarkable properties for applications as ozone gas sensing materials. † Electronic supplementary information (ESI) available: The detailed synthesis procedure of hierarchical ZnO nanorod-like structures, Zn K-edge XANES spectrum of ZnO nanorods, EDX spectrum, and electrical response of ZnO nanorods under UV irradiation. See

ZnO nanocrystals by chemical route for optical gas sensing

2008 IEEE Sensors, 2008

ZnO nanocrystals were prepared from the decomposition of zinc(II) 2-ethylhexanoate. Soluble nanocrystals with a size ranging from about 5 to 8 nm were obtained. The powders obtained were tested as optical gas sensor based on photoluminescence (PL) variation with NO2, ethanol and relative humidity at room temperature (RT).

Zinc oxide nanostructured layers for gas sensing applications

Laser Physics, 2011

Various kinds of zinc oxide (ZnO) nanostructures, such as columns, pencils, hexagonal pyramids, hexagonal hierarchical structures, as well as smooth and rough films, were grown by pulsed laser deposition using KrF and ArF excimer lasers, without use of any catalyst. ZnO films were deposited at substrate temper atures from 500 to 700°C and oxygen background pressures of 1, 5, 50, and 100 Pa. Quite different morphol ogies of the deposited films were observed using scanning electron microscopy when different laser wave lengths (248 or 193 nm) were used to ablate the bulk ZnO target. Photoluminescence studies were performed at different temperatures (down to 7 K). The gas sensing properties of the different nanostructures were tested against low concentrations of NO 2 . The variation in the photoluminescence emission of the films when exposed to NO 2 was used as transduction mechanism to reveal the presence of the gas. The nanostructured films with higher surface to volume ratio and higher total surface available for gas adsorption presented higher responses, detecting NO 2 concentrations down to 3 ppm at room temperature.

Fast-response ozone sensor with ZnO nanorods grown by chemical vapor deposition

Sensors and Actuators B: Chemical, 2010

Nanostructures of ZnO grown by chemical vapor deposition were used as sensing materials. These materials, ZnO nanorods, were characterized by scanning electron microscopy (SEM), photoluminescence (PL) and X-ray diffraction (XRD). The ozone sensing properties of various ZnO nanomaterials were studied. Under 2.5 ppm ozone, ZnO nanorods showed a rapid response time of 45 s and recovery time of 5 s, and the sensor response (S, the ratio of the resistance in an ozone gas without UV to resistance in air with UV, S = R ozone /R air) is 850. The low defect density and high mobility accounts for the fast response and recovery times. The sensor response was measured in the range from 1 to 2.5 ppm ozone in this study.

Synthesis and characterisation of ZnO nanoparticles

International Journal of Nanoparticles, 2009

A physical vapour condensation method is used to synthesise the nanoparticles of ZnO. The size of these nanoparticles varies from 40 nm to 100 nm. Mostly, these nanoparticles are spherical in shape but contain some impurities. The XRD data shows a sharp peak at 36.87°, which is very close to that of zinc oxide nanoparticles grown by oxidation in the presence of ambient gases i.e., oxygen mixed with argon. From UV visible spectra of these nanoparticles, a peak at 381 nm and 373 nm is observed. The broad peak at 373 nm is responsible for the conversion of zinc into zinc oxide.

Gas sensing properties of zinc oxide nanostructures prepared by thermal evaporation

Applied Physics A-materials Science & Processing, 2007

Progress has been achieved in the synthesis, structural characterization and physical properties investigation of nanostructures. We have focused our attention on zinc oxide nanostructures. We report on the growth of ZnO nanostructures using vapour phase technique. We have synthesized, depending on the growth conditions, different nanostructures such as wires and combs of zinc oxide. ZnO nanowires electrical properties have been characterised in presence of different gases, the results highlight remarkable response to acetone and ethanol with detection limits lower than 1 ppm.

Photoluminescence investigation on the gas sensing property of ZnO nanorods prepared by plasma-enhanced CVD method

Sensors and Actuators B: Chemical, 2010

Gas sensing property of ZnO nanorods prepared by plasma-enhanced chemical vapor deposition (CVD) method is studied using formaldehyde as the probe gas, and the intrinsic defects are investigated by photoluminescence (PL). The results show that high ratio of visible to ultraviolet luminescence cannot account for high gas response. The PL spectra are Gaussian decomposed to subpeaks according to their origination, which are separated into donor-(DL) and acceptor-related (AL) ones. A conclusion is derived that where the content of DL is high and that of AL is low, the gas response is high. This conclusion is further confirmed by tuning the PL spectra and gas sensing property through annealing in different atmospheres.

ZnO nanoparticles or ZnO films: A comparison of the gas sensing capabilities

Sensors and Actuators B: Chemical, 2009

Zinc oxide is an interesting material for bio and chemical sensors. It is a semiconducting metal oxide with potential as an integrated multisensing sensor platform, which simultaneously detects parameters like change in field effect, mass and surface resistivity. In this investigation we have used resistive sensor measurements regarding the oxygen gas sensitivity in order to characterize sensing layers based on electrochemically produced ZnO nanoparticles and PE-MOCVD grown ZnO films. Proper annealing procedures were developed in order to get stable sensing properties and the oxygen sensitivity towards operation temperature was investigated. The ZnO nanoparticles showed a considerably increased response to oxygen as compared to the films. Preliminary investigations were also performed regarding the selectivity to other gases present in car exhausts or flue gases.