Fast formaldehyde gas sensing response properties of ultrathin SnO2 nanosheets

Indoor formaldehyde detection is of great important at present. Using efficient solvothermal method, nanosheet-constructed and nanorod-constructed hierarchical tin dioxide (SnO2) microspheres were successfully synthesized in this work and used for the gas sensing material for indoor formaldehyde application. The as-prepared two kinds of SnO2 gas sensing materials were applied to fabricate the gas sensors and formaldehyde gas sensing experiments were carried out. The HCHO gas sensing tests indicate that the gas response of the nanosheet-constructed SnO2 microspheres is about 1.7 times higher than that of the nanorod-constructed SnO2 microspheres. In addition, both of the two SnO2 based gas sensors show almost fast response and recovery time to HCHO gas. For the nanosheet-constructed microspheres, the response value is estimated to be 32.0 at 350 °C to 60 ppm formaldehyde gas, while the response and recovery times are 7 and 5 s, respectively. The simple and efficient preparation method and improved gas sensing properties show that the as-synthesized hierarchical SnO2 microsphere that is constructed by a large amount of nanosheets exhibits significant potential application for the indoor formaldehyde sensing.

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NO2 Gas Sensor Based on SnSe/SnSe2p-n Hetrojunction

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19278 ◽

2021 ◽

Vol 21 (9) ◽

pp. 4779-4785

Author(s):

Sanju Rani ◽

Manoj Kumar ◽

Yogesh Singh ◽

Monika Tomar ◽

Anjali Sharma ◽

...

Keyword(s):

Room Temperature ◽

Gas Sensing ◽

Limit Of Detection ◽

Fast Response ◽

Desorption Kinetics ◽

Low Concentration ◽

Sensing Applications ◽

Recovery Times ◽

Nanostructured Sensor ◽

Evaporation Technique

Air pollution is a big concern as it causes harm to human health as well as environment. NO2 can cause several respiratory diseases even in low concentration and therefore an efficient sensor for detecting NO2 at room temperature has become one of the priorities of the scientific community. Although two dimensional (2D) materials (MoS2 etc.) have shown potential for NO2 sensing at lower temperatures, but these have poor desorption kinetics. However, these limitations posed by slow desorption can be overcome, if a material in the form of a p-n junction can be suitably employed. In this work, ~150 nm thick SnSe2 thin film has been deposited by thermally evaporating in-house made SnSe2 powder. The film has been studied for its morphological, structural and gas sensing applications. The morphology of the film showed that the film consists of interconnected nanostructures. Detailed Raman studies further revealed that SnSe2 film had 31% SnSe. The SnSe-SnSe2 nanostructured sensor showed a response of ~112% towards 5 ppm NO2 at room temperature (30 °C). The response and recovery times were ~15 seconds and 10 seconds, respectively. Limit of detection for NO2 was in sub-parts per million (sub-ppm) range. The device demonstrated a better response towards NO2 compared to NH3, CH4, and H2. The mechanism of room temperature fast response, recovery and selective detection of NO2 independent of humidity conditions has been discussed based on physisorption, charge transfer, and formation of SnSe-SnSe2 (p-n) nano-junctions. Depositing a nanostructured film consisting of nano-junctions using an industrially viable thermal evaporation technique for sensing a very low concentration of NO2 is the novelty of this work.

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Facile Chemical Bath Synthesis of SnS Nanosheets and Their Ethanol Sensing Properties

Sensors ◽

10.3390/s19112581 ◽

2019 ◽

Vol 19 (11) ◽

pp. 2581 ◽

Cited By ~ 3

Author(s):

Wei Shan ◽

Zhengqian Fu ◽

Mingsheng Ma ◽

Zhifu Liu ◽

Zhenggang Xue ◽

...

Keyword(s):

High Performance ◽

Gas Sensing ◽

Raw Materials ◽

Orthorhombic Phase ◽

Ethanol Vapor ◽

Fast Response ◽

Sensing Applications ◽

Recovery Times ◽

Response And Recovery ◽

Ethanol Sensing

Tin(II) monosulfide (SnS) nanosheets were synthesized using SnCl4•5H2O and S powders as raw materials in the presence of H2O via a facile chemical bath method. Orthorhombic phase SnS nanosheets with a thickness of ~100 nm and lateral dimensions of 2~10 μm were obtained by controlling the synthesis parameters. The formation of a SnO2 intermediate is key to the valence reduction of Sn ions (from IV to II) and the formation of SnS. The gas sensors fabricated from SnS nanosheets exhibited an excellent response of 14.86 to 100 ppm ethanol vapor when operating at 160 °C, as well as fast response and recovery times of 23 s and 26 s, respectively. The sensors showed excellent selectivity for the detection of ethanol over acetone, methanol, and ammonia gases, which indicates the SnS nanosheets are promising for high-performance ethanol gas sensing applications.

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A Room-Temperature CNT/Fe3O4 Based Passive Wireless Gas Sensor

Sensors ◽

10.3390/s18103542 ◽

2018 ◽

Vol 18 (10) ◽

pp. 3542 ◽

Cited By ~ 5

Author(s):

Tao Guo ◽

Tianhao Zhou ◽

Qiulin Tan ◽

Qianqian Guo ◽

Fengxiang Lu ◽

...

Keyword(s):

Carbon Nanotube ◽

Gas Sensor ◽

Room Temperature ◽

Gas Sensing ◽

Low Cost ◽

Fast Response ◽

Sensing Material ◽

Recovery Times ◽

Response And Recovery ◽

Good Repeatability

A carbon nanotube/Fe3O4 thin film-based wireless passive gas sensor with better performance is proposed. The sensitive test mechanism of LC (Inductance and capacitance resonant) wireless sensors is analyzed and the reason for choosing Fe3O4 as a gas sensing material is explained. The design and fabrication process of the sensor and the testing method are introduced. Experimental results reveal that the proposed carbon nanotube (CNT)/Fe3O4 based sensor performs well on sensing ammonia (NH3) at room temperature. The sensor exhibits not only an excellent response, good selectivity, and fast response and recovery times at room temperature, but is also characterized by good repeatability and low cost. The results for the wireless gas sensor’s performance for different NH3 gas concentrations are presented. The developed device is promising for the establishment of wireless gas sensors in harsh environments.

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Dual-functional ultraviolet photodetector with graphene electrodes on AlGaN/GaN heterostructure

Scientific Reports ◽

10.1038/s41598-020-79135-y ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Bhishma Pandit ◽

E. Fred Schubert ◽

Jaehee Cho

Keyword(s):

Bias Voltage ◽

Threshold Voltage ◽

Response Times ◽

Fast Response ◽

Dual Functional ◽

Photocurrent Generation ◽

Recovery Times ◽

Slow Rise ◽

Generation Mechanisms ◽

Gan Heterostructure

AbstractA dual-functional ultraviolet (UV) photodetector with a large UV-to-visible rejection ratio is presented, in which interdigitated finger-type two-dimensional graphene electrodes are introduced to an AlGaN/GaN heterostructure. Two photocurrent generation mechanisms of photovoltaic and photoconductive dominances coexist in the device. The dominance of the mechanisms changes with the induced bias voltage. Below a threshold voltage, the device showed fairly low responsivities but fast response times, as well as a constant photocurrent against the induced bias. However, the opposite characteristics appeared with high bias voltage. Specifically, above the threshold voltage, the device showed high responsivities with additional gain, but slow rise and recovery times. For instance, the responsivity of 10.9 A/W was observed with the gain of 760 at the induced bias voltage of 5 V. This unique multifunctionality enabled by the combination of an AlGaN/GaN heterostructure with graphene electrodes facilitates the development of a single device that can achieve multiple purposes of photodetection.

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ACETONE SENSING PROPERTIES OF HIERARCHICAL ZnO URCHINLIKE STRUCTURES BY HYDROTHERMAL PROCESS

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s101623721250010x ◽

2012 ◽

Vol 24 (02) ◽

pp. 99-103 ◽

Cited By ~ 5

Author(s):

Zheng Lou ◽

Yingliang Feng ◽

Xiangwei Liu ◽

Lili Wang ◽

Tong Zhang

Keyword(s):

Gas Sensing ◽

Operating Temperature ◽

Hydrothermal Process ◽

Hierarchical Structures ◽

Fast Response ◽

Hydrothermal Route ◽

Recovery Times ◽

Response And Recovery ◽

The Individual ◽

Excellent Selectivity

The nanorods bundles (urchinlike) ZnO microspheres, consisting of closely packed nanorods with wideness of about 50 nm, have been successfully synthesized by a hydrothermal route at the temperature of 140°C. The individual hierarchical ZnO microsphere ranged from 3.5 to 4.5 μm in diameter. Most importantly, ZnO hierarchical microsphere sensor exhibits excellent selectivity and fast response to acetone. Response and recovery times were 1 s and 3 s when the sensor was exposed to 100 ppm acetone at an operating temperature of 320°C. Thus, hierarchical structures play a significant role in the field of gas sensing.

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Flexible Ni/NiOx-Based Sensor for Human Breath Detection

Materials ◽

10.3390/ma15010047 ◽

2021 ◽

Vol 15 (1) ◽

pp. 47

Author(s):

Le Duc-Anh Ho ◽

Vu Binh Nam ◽

Daeho Lee

Keyword(s):

Photoelectron Spectroscopy ◽

Mechanical Stability ◽

Gas Sensing ◽

Single Layer ◽

Fast Response ◽

Single Step ◽

Chemical Components ◽

Human Breath ◽

Flexible Polymer ◽

Recovery Times

We developed a simple methodology to fabricate an Ni/NiOx-based flexible breath sensor by a single-step laser digital patterning process of solution-processed NiOx thin-film deposited using NiOx nanoparticle ink. Laser-induced reductive sintering phenomenon enables for the generation of three parts of Ni electrodes and two narrow NiOx-sensing channels in between, defined on a single layer on a thin flexible polymer substrate. The Ni/NiOx-based breath sensor efficiently detects human breath at a relatively low operating temperature (50 °C) with fast response/recovery times (1.4 s/1.7 s) and excellent repeatability. The mechanism of the gas-sensing ability enhancement of the sensor was investigated by X-ray photoelectron spectroscopy analysis. Furthermore, by decoupling of the temperature effect from the breathing gas, the response of the sensor due to the temperature alone and due to the chemical components in the breathing gas could be separately evaluated. Finally, bending and cyclic bending tests (10,000 cycles) demonstrated the superior mechanical stability of the flexible breath sensor.

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BaTiO3 Based Nanostructures for Humidity Sensing Applications

Proceedings ◽

10.3390/proceedings2019015009 ◽

2019 ◽

Vol 15 (1) ◽

pp. 9 ◽

Cited By ~ 2

Author(s):

Soderznik ◽

Fabrega ◽

Hernandez-Ramirez ◽

Prades ◽

Čeh

Keyword(s):

Gas Sensing ◽

Response Times ◽

Fast Response ◽

Electronic Conduction ◽

Oxide Materials ◽

Sensing Applications ◽

Sensor Properties ◽

Device Applications ◽

Great Relevance ◽

Gas Sensing Device

Our contribution focuses on humidity gas-sensing device formation of metal oxide materials such as BaTiO3 nanorods and TiO2-BaTiO3 nanotubes. Processing of humidity sensors based on BaTiO3 nanostructured materials, that can operate under severe environmental conditions is of great relevance due to their small size and small weight. As a result, these sensors possess high stability, fast response times and reproducibility. Furthermore, gas sensor properties are not only interesting in terms of device applications, but also pave the way to study in deep ionic and electronic conduction mechanisms in individual nano-based devices.

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Zinc Oxide/Reduced Graphene Oxide Nanocomposites for Rapid Detection of Toluene Gas at Room Temperature

Sensor Letters ◽

10.1166/sl.2020.4288 ◽

2020 ◽

Vol 18 (10) ◽

pp. 745-749

Author(s):

Chih-Chia Wang ◽

Chiu-Hung Liu ◽

Hsuan-Hua Hsieh ◽

Chih-Wei Tang ◽

Chen-Bin Wang

Keyword(s):

Zinc Oxide ◽

Graphene Oxide ◽

Reduced Graphene Oxide ◽

Room Temperature ◽

Gas Sensing ◽

Fast Response ◽

Reduced Graphene ◽

New Strategy ◽

Recovery Times ◽

Response And Recovery

In this study, a nanostructured zinc oxide/reduced graphene oxide (ZnO/rGO) composite was deposited on a quartz crystal microbalance (QCM) as a toluene gas sensor at room temperature. A series of ZnO, rGO and ZnO/rGO sensing materials was fabricated and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and Raman spectroscopy. There was significant efficiency of the ZnO/rGO composite on the sensing performance for toluene. For specific gas fluxes, the nanostructured ZnO/rGO offered sufficient paths and region for vapor diffusion and adsorption. The sensing test results illustrated that the nanostructured ZnO/rGO composite showed significant enhancement in the frequency shifts (△f) for toluene comparing to pure ZnO and rGO. Also, the ZnO/rGO-coated QCM sensor displayed a fast response (both the response and recovery times < 30 s) and reproducibility for sensing toluene gas at room temperature. We believe that the novel insights on ambient temperature gas sensing on nanostructured ZnO/rGO composite could provide a new strategy for preparing a highly efficient sensing materials.

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Screen-Printed Fe2O3/ZnO thick films for gas sensing applications

Journal of Microelectronics and Electronic Packaging ◽

10.4071/1551-4897-2.1.25 ◽

2005 ◽

Vol 2 (1) ◽

pp. 25-39 ◽

Cited By ~ 5

Author(s):

K. Arshak ◽

I. Gaidan ◽

L. Cavanagh

Keyword(s):

Gas Sensing ◽

Response Times ◽

Thick Films ◽

Ethanol Vapor ◽

Vapor Concentration ◽

Resistance Change ◽

Glass Substrates ◽

Sensing Applications ◽

Recovery Times ◽

Composition Ratios

This paper investigates iron-oxide and zinc-oxide thick-films for gas sensing applications. The films were printed onto glass substrates with silver electrodes. The effects of propanol, methanol and ethanol vapor on the devices at room temperature (in the concentration range 500–2000ppm) were investigated. The percentage relative resistance change, ΔR = ((Rgas − Rair)/Rair) ×100, was seen to increase linearly with increasing gas vapor concentration. The sensitivity of the films to the gas vapor was determined from the slope of the graphs. It was observed that various film compositions showed a higher sensitivity to propanol than to methanol and ethanol. Moreover, the sensitivity to propanol increased from 0.077 to 0.166 to 0.173%/ppm for the three samples with molecular weight composition ratios of: 90%/10%, 80/20% and 70%/30% of Fe2O3 to ZnO respectively. The response times of sensors 1, 2 and 3 (to 1000ppm step changes in propanol concentration) were 48.6 seconds, 86.4 seconds and 76.5 seconds, while the recovery times were 117 seconds, 186 seconds and 153 seconds respectively.

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