Room temperature NO2 sensing performance of Ag nanoparticles modified VO2 nanorods

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.

“…Some strategies were developed to enhance the performance of the Ag-decorated SMOs-based gas sensors, such as designing special nanostructures, increasing surface defects, constructing heterostructures, and introducing light illumination. Different morphologies of Ag-decorated SMOs materials such as nanoparticles [ 293 ], nanorods [ 294 ], nanofibers [ 295 ], nanowires [ 42 ], nanosheets [ 296 ], microspheres [ 297 ], and nanoflowers [ 298 ], were studied for the enhancement of gas sensing properties with high sensitivity, lower operation temperatures, lower detection limit, and remarkable selectivity. Owing to uniform distribution and abundant surface oxygen vacancies, the Ag-decorated nanomaterials display strong catalytic activity compared with pure nanomaterials and high photocatalytic efficiency applied in light-assisted gas 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.

“…[31,32] VO X and its composites also show excellent performance in physically adsorbing and chemically interacting with several gases, including nitrogen dioxide, ammonia, hydrogen, and methane, among others. [33][34][35][36] However, the application of VO X and its composites is limited by complex synthesis methods, including spray pyrolysis, [37] hydrothermal, [38] sol-gel method, [39] electrospinning, [40] chemical vapor deposition, [41] and precipitation. [42] The recent report that directly synthesizes VO X with laser [43] provides inspiration and opportunities to directly laser write the VO X /LIG foam composites.…”

Section: Introductionmentioning

confidence: 99%

Vanadium Oxide‐Doped Laser‐Induced Graphene Multi‐Parameter Sensor to Decouple Soil Nitrogen Loss and Temperature

et al. 2023

Monitoring nitrogen utilization e ciency and soil temperature in agricultural systems for timely intervention is essential to monitor crop health, promote sustainable and precision agriculture, and reduce environmental pollution. Therefore, it is of vital signi cance to develop a multi-parameter sensor for effectively and accurately decoupled detection of nitrogen loss and soil temperature, which is yet to be reported. Herein, this work presents a high-performance multi-parameter sensor based on vanadium oxide (VO X )-doped laser-induced graphene (LIG) foam to completely decouple nitrogen oxides (NO X ) and temperature. By exploiting the laser-assisted synthesis, the highly porous 3D VO X -doped LIG foam composite is readily obtained by laser scribing of vanadium sul de (V 5 S 8 )-doped block copolymer and phenolic resin self-assembled lms. Compared with the intrinsic LIG, the heterojunction formed at the LIG/VO X interface provides the sensor with a signi cantly enhanced response to NO X and an ultralow limit of detection (LOD) of 3 ppb at room temperature. Meanwhile, the sensor can accurately detect temperature over a wide linear range of 10-110℃ with a small detection limit of 0.2℃. The encapsulation of the sensor with a soft membrane further allows for temperature sensing without being affected by NO X , presenting an effective strategy to decouple nitrogen loss and soil temperature for accurate soil environmental monitoring. The sensor without encapsulation but operated at elevated temperature removes the in uences of ambient relative humidity and temperature variations for accurate NO X measurements. The capability to simultaneously detect ultra-low NO X concentrations and small temperature changes paves the way for the development of future multimodal electronic devices with decoupled sensing mechanisms for health monitoring and precision agriculture.