Ultraviolet light-emitting diode-assisted highly sensitive room temperature NO<sub>2</sub> gas sensors based on low-temperature solution-processed ZnO/TiO<sub>2</sub> nanorods decorated with plasmonic Au nanoparticles

Xia

et al. 2022

ACS Appl. Nano Mater.

The oriented design and controllable preparation of sensing materials are extremely important and meaningful attributes that not only contribute to the realization of desirable gas-sensing properties but also facilitate the validation of the sensing mechanism. Because of the spatial effect derived from micelle assemblies formed by surfactant molecules under certain circumstances, radial growth of ZnO crystals is successfully suppressed in this work, which leads to the formation of ZnO nanowires with a larger aspect ratio. Furthermore, anionic surfactants of the same series but with longer carbon chains were utilized to create a greater spatial effect, which leads to more serious radial inhibition and, eventually, ever-increasing aspect ratios for the products. Except for a change in morphology, multiple characterization methods, such as XRD, FT-IR, and XPS, confirm the in situ doping/functionalization of surfactant molecules into ZnO crystals during the preparation process, which, on one hand, provide important evidence for the analysis of the product formation mechanism, and, on the other hand, serve as active sites for light-enhanced sensing. In subsequent gas-sensing tests, all surfactant−induced ZnO samples were applied as sensing materials to detect NO 2 at room temperature (RT, 25 °C) in the dark, which show an increased response with increasing aspect ratio. In particular, at RT, the response toward 10 ppm NO 2 of C16−ZnO with the highest aspect ratio reaches 271% in the dark, which is 24.64 times higher than that of pure ZnO without surfactant-assisted synthesis. Under UV irradiation, the response of C16−ZnO toward 10 ppm NO 2 is further enhanced to 602% at RT, and this magnitude (2.22 times) of response improvement compared with that in the dark is maximal among all surfactant−induced ZnO samples. Moreover, the response/recovery time of C16−ZnO toward 10 ppm NO 2 at RT is found to be drastically decreased from 393/953 s in the dark to 58/91 s under UV irradiation.

Section: Resultsmentioning

confidence: 99%

ZnO Nanowires with Increasing Aspect Ratios for Room-Temperature NO₂ Gas Sensing

Xia

et al. 2022

ACS Appl. Nano Mater.

“…UV photoactivation can perform to reduce the operating temperature of SMO-based gas sensors. For example, Kwon et al [ 271 ] prepared Au NPs decorated ZnO/TiO 2 core–shell nanorods for NO 2 gas detection. The fabricated ZnO/TiO 2 nanorods decorated with Au NPs demonstrated 9 times higher gas sensitivity and shorter response/recovery time than ZnO nanorods based sensors.…”

Section: Single Noble Metal-decorated Smos-based Gas Sensorsmentioning

confidence: 99%

Advances in Noble Metal-Decorated Metal Oxide Nanomaterials for Chemiresistive Gas Sensors: Overview

et al. 2023

Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring, exhaled breath diagnosis, and food freshness analysis. Among various chemiresistive sensing materials, noble metal-decorated semiconducting metal oxides (SMOs) have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals. This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures (e.g., nanoparticles, nanowires, nanorods, nanosheets, nanoflowers, and microspheres) for high-performance gas sensors with higher response, faster response/recovery speed, lower operating temperature, and ultra-low detection limits. The key topics include Pt, Pd, Au, other noble metals (e.g., Ag, Ru, and Rh.), and bimetals-decorated SMOs containing ZnO, SnO2, WO3, other SMOs (e.g., In2O3, Fe2O3, and CuO), and heterostructured SMOs. In addition to conventional devices, the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed. Moreover, the relevant mechanisms for the sensing performance improvement caused by noble metal decoration, including the electronic sensitization effect and the chemical sensitization effect, have also been summarized in detail. Finally, major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.

“…Finally, we have compared the gas-sensing performances of different types of gas sensors described above with research papers published by other research groups from Korea [ 184 , 185 , 186 , 187 , 188 , 189 , 190 , 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 , 201 , 202 , 203 , 204 , 205 , 206 , 207 , 208 , 209 , 210 , 211 , 212 , 213 , 214 , 215 , 216 , 217 , 218 , 219 , 220 , 221 , 222 ] in Table 3 .…”

Section: Other Resistive-based Gas Sensors (Glass/silicon/mof-based Gas Sensors)mentioning

confidence: 99%

State-of-the-Art Research on Chemiresistive Gas Sensors in Korea: Emphasis on the Achievements of the Research Labs of Professors Hyoun Woo Kim and Sang Sub Kim

Navale

Mirzaei

Majhi

et al. 2021

Sensors

This review presents the results of cutting-edge research on chemiresistive gas sensors in Korea with a focus on the research activities of the laboratories of Professors Sang Sub Kim and Hyoun Woo Kim. The advances in the synthesis techniques and various strategies to enhance the gas-sensing performances of metal-oxide-, sulfide-, and polymer-based nanomaterials are described. In particular, the gas-sensing characteristics of different types of sensors reported in recent years, including core–shell, self-heated, irradiated, flexible, Si-based, glass, and metal–organic framework sensors, have been reviewed. The most crucial achievements include the optimization of shell thickness in core–shell gas sensors, decrease in applied voltage in self-heated gas sensors to less than 5 V, optimization of irradiation dose to achieve the highest response to gases, and the design of selective and highly flexible gas sensors-based WS2 nanosheets. The underlying sensing mechanisms are discussed in detail. In summary, this review provides an overview of the chemiresistive gas-sensing research activities led by the corresponding authors of this manuscript.