Characteristics of Gas Sensors Based on Co-Doped ZnO Nanorod Arrays

Abstract

In this investigation, gas sensors based on zinc oxide (ZnO) nanorods (NRs) with Co concentration were successfully fabricated and explored. A 100 nm-thick ZnO film was deposited as a seed layer onto Corning glass substrate via radio frequency (RF) magnetron sputtering technique. Then, Co-doped ZnO (CZO) NR arrays were grown by using a simple chemical bath deposition (CBD) method at 95 °C for 3 h and annealing at 450 °C, in which the Co-doping contents are 0, 5, and 10 mM. The surface-tovolume ratio of CZO NRs was higher than that of the pure ZnO structure. X-ray diffraction (XRD) results showed that the synthesised NRs were a single crystalline of the hexagonal wurtzite structure with uniform growth orientation of the c-axis. In addition, increasing ethanol (C 2 H 5 OH) response depends on O vacancy (V O ) adsorption, which is measured via photoluminescence (PL) emission. Compared with pure ZnO NRs, the results showed that the CZO-5 (with 5 mM Co solution) NRs exhibited a superior sensitivity in C 2 H 5 OH gas applications and a fast response/recovery time. Meanwhile, the CZO-5 gas sensor presented a high response rate of 90.71% at 300 °C operating temperature when the concentration of ambient C 2 H 5 OH gas was 100 ppm.

Characteristics of Field Emitters on the Basis of Pd-Adsorbed ZnO Nanostructures by Photochemical Method

“…(3) The ZnO material with a hexagonal wurtzite structure reveals nontoxicity, is cheap, and has a simple design. − Owing to its remarkable property, ZnO has become the popular research material in the modern day. The ZnO morphologies with different geometrical nanostructures have been studied using different methods, for instance, hydrothermal method (HM), pulsed laser deposition, furnace, and electrochemical deposition. − Among these preparation processes, HM has several merits, such as simple and controllable process, high yield, uniform morphology feature, and homogeneous size; the nanostructure is easily synthesized at low temperature. Based on these advantages, the chemical bath solution is the most suitable process for the preparation of ZnO nanostructures.…”

Selective Detection of Carbon Monoxide on P-Block Doped Monolayers of MoTe2

“… 7 , 8 Consequently, CO sensors are required in various situations, and thus the detection methods are constantly perfected. 9 − 14 At the same time, new prospects are investigated, 15 − 19 among which novel nanomaterials have gained noticeable interest. 20 − 25 …”

“…The health effects of CO depend on its concentration and the length of exposure. However, early symptoms of prolonged exposure can occur at concentrations as low as 35 ppm, while 3200 ppm can cause death within 30 min. , Consequently, CO sensors are required in various situations, and thus the detection methods are constantly perfected. − At the same time, new prospects are investigated, − among which novel nanomaterials have gained noticeable interest. − …”

Recent Advances in ZnO-Based Carbon Monoxide Sensors: Role of Doping

“…Furthermore, parameters such as the selectivity, sensitivity, response time, and stability of the gas sensors are improved by adding different dopant elements. To date, various sensors have been designed and fabricated using doped ZnO to improve the operating conditions at low temperatures, and retain high sensitivity at low concentrations, good selectivity, and fast response/recovery times, in addition to good repeatability and stability [ 6 , 29 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ].…”