Preparation of Au@ZnO Nanofilms by Combining Magnetron Sputtering and Post-Annealing for Selective Detection of Isopropanol

Abstract

We demonstrate the highly sensitive and fast response/recovery gas sensors for detecting isopropanol (IPA), in which the Au-nanoparticles-modified ZnO (Au@ZnO) nanofilms act as the active layers. The data confirm that both the response and the response/recovery speed for the detection of IPA are significantly improved by adding Au nanoparticles on the surface of ZnO nanofilms. The gas sensor with an Optimum Au@ZnO nanofilm exhibits the highest responses of 160 and 7 to the 100 and 1 ppm IPA at 300 °C, which indicates high sensitivity and a very low detecting limit. The sensor also exhibits a very short response/recovery time of 4/15 s on the optimized Au@ZnO nanofilm, which is much shorter than that of the sensor with a pure ZnO nanofilm. The mechanisms of the performance improvement in the sensors are discussed in detail. Both the electronic sensitization and the chemical sensitization of the ZnO nanofilms are improved by the modified Au nanoparticles, which not only regulate the thickness of the depletion layer but also increase the amount of adsorbed oxygen species on the surfaces. This work proposes a strategy to develop a highly sensitive gas sensor for real-time monitoring of IPA.

Highly response gas sensor based the Au-ZnO films processed by combining magnetron sputtering and Ar plasma treatment

“…Wang et al demonstrated the sensor based on p-NiO/n-ZnO also showed good selectivity, high response (R a /R g = 221.3 to 400 ppm IPA) and fast response rate (less than 10 s) [9]. In our previous work, IPA sensors based on Au functionalized ZnO nanofilms were also obtained, which showed a low detection limit of 1 ppm at 300 °C, needing further to be improved [10]. As mentioned above, ZnO based sensitive materials prepared by chemical synthesis methods exhibit good sensing properties for IPA, but there are still some urgent issues that need to be addressed, such as poor repeatability, complex preparation process, and susceptibility of the sensing layer to detachment from the electrodes.…”

The enhanced sensing properties of MOS-based resistive gas sensors by Au functionalization: a review

“…Functionalizing ZnO with Au can also profoundly influence the detection limit of the ZnO sensor for target gases, with some samples demonstrating detection capabilities in the ppb range. Wang et al 87 reported the use of Au/ZnO nanofilm for isopropanol sensing, with the sensor exhibiting a high response of 160 to 100 ppm isopropanol and 7 to 1 ppm isopropanol at 300 °C, displaying surprising response and lower detection limits. Saito et al 88 reported a pyramid-shaped ZnO particle loaded with Au NPs for detecting isoprene.…”

Au-modified α-Fe2O3 nanoparticles for ultrasensitive isopropanol detection

“…The optimum working temperature was reduced with the increasing concentration of Au modification, and the response/recovery times were also shortened. 30 The advancement of the gas-sensing performances could be ascribed to the sensitization of Au, whereby Au NPs promote the conversion of oxygen molecules, leading to more oxygen ions reacting with the target gas and achieving an enhancement in the gas-sensitive response. Besides, the synergistic electronic interactions between Au ( φ = 5.1 eV) and α-Fe 2 O 3 ( φ = 5.88 eV) can also thicken the electron-depletion layer on the surface, 31 thus improving the sensing performance.…”