Enhancement of Ethanol Sensing Properties by Alloying ${\rm TiO}_{2}$ With ZnO Tetrapods

Abstract

The Ti Zn 1 O tetrapods were synthesized using simple thermal oxidation method from Zn and TiO 2 mixture. The tetrapods exhibited single crystalline hexagonal wurtzite structure with the prefer growth direction of [0002] along the legs. The sensors based on Ti Zn 1 O tetrapods were fabricated and investigated the ethanol sensing properties. The FE-SEM, HRTEM, SAED, XRD, and RS results suggested that Ti Zn 1 O alloy was formed with a slightly decrease of c-axis lattice parameter. The decrease of sensor resistance under ethanol atmosphere was observed and suggested that the Ti Zn 1 O tetrapods possessed n-type property of semiconductor similar to ZnO. TheTi Zn 1 O tetrapod sensors exhibited higher sensitivity than that of pure ZnO tetrapod sensors for entire ethanol concentration with optimum operating temperature of 300 C. Thus, the enhancement of sensitivity due to alloying TiO 2 with the ZnO tetrapods was observed and maybe explained by an increase of adsorbed oxygen ions due to substitution of Ti atom into Zn atom.Also, the slope value of the plot between log( 1) and log suggested that adsorbed oxygen ion species at the surface of the Ti Zn 1 O tetrapods was O 2 which was same as pure ZnO tetrapods. Finally, these results have an important implication for a development of ethanol sensors based on metal oxide semiconductors for alcohol breath analyzer.

Characterizations of octahedral zinc oxide synthesized by sonochemical method

“…It has a wide energy bandgap and large excitation binding energy with high chemical stability and radiation resistance. For these reasons, it has been studied for applications in short-wavelength lasers and light emitting diodes [8][9][10][11][12], sensors [13][14][15][16][17], solar cells [18][19][20][21][22][23], transistors [24,25], varistors [26][27][28][29], piezoelectric devices [30,31], and microwave absorbers [32,33]. Furthermore, nanoscale ZnO has been implemented in functional composites such as an additive to modify piezoelectric materials [34] and polymers [35].…”

“…Such structures have a large surface to volume ratio and are advantageous in gas sensors and photocatalytic applications [15][16][17][46][47][48][49]. From a structural point of view, octahedral ZnO is of interest because of its relation to eight tetrahedral crystals, i.e.…”

Response of a Zn2TiO4 Gas Sensor to Propanol at Room Temperature

“…Thick film gas sensors, based on a Zn 2 TiO 4 semiconductor with different ZnO and Ti 2 O contents were developed and tested for sensing propanol vapors. The electrochemical results from these sensors showed: They had good sensitivity to propanol vapor at room temperature;The response of the sensors monotonically increased as the gas concentration increased;XRD measurements of the screen-printed sensing materials illustrated that the final compositions (Zn 2 TiO 4 to TiO 2 ) depended on the ratio of TiO 2 to ZnO used in preparing the mixtures before being heated;SEM images of the films showed granular microstructure ranging from 2–5 microns;Using copper as an electrode material makes sensors cost effective compared to sensors with Pt and Au electrodes;The developed sensors consume very low power compared with those sensors reported in the literature in [5,12], as heating of the sensing material is not required;The simple structure of the sensor with copper electrodes makes it easy to interface with electrical systems;The developed sensors can be used in various applications at room temperature, including as gas safety monitors;Further detailed studies are required to better understand the interaction mechanism between the sensing material and the tested gas.…”

“…The developed sensors consume very low power compared with those sensors reported in the literature in [5,12], as heating of the sensing material is not required;…”

“…TiO 2 and ZnO, or mixture of both, have been used by many researchers to detect different gases. For example, TiO 2 /ZnO has been used to detect ethanol [12,13], ZnO to detect NO 2 [14], and TiO 2 to detect chloroform [15]. …”