UV-enhanced NO2 gas sensors based on In2O3/ZnO composite material modified by polypeptides

2021 ◽  
Author(s):  
Zhihua Ying ◽  
Teng Zhang ◽  
Chao Feng ◽  
Fei Wen ◽  
Lili Li ◽  
...  

Abstract This present study reported a high-performance gas sensor, based on In2O3/ZnO composite material modified by polypeptides, with a high sensibility to NO2, where the In2O3/ZnO composite was prepared by a one-step hydrothermal method. A series of results through material characterization technologies showed the addition of polypeptides can effectively change the morphology and size of In2O3/ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In2O3/ZnO composite modified by polypeptides increased the active sites on the surface. At the same time, the gas sensing properties of four different ratios of polypeptide-modified In2O3/ZnO gas sensors were tested. It was found that the In2O3/ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In2O3/ZnO-10 gas sensor showed a strong linear relationship with the NO2 gas concentration. When the NO2 gas concentration was 20 ppm, the response time was as quick as 19s, and the recovery time was 57s. Finally, based on the obtained experimental characterization results and energy band structure analysis, a possible gas sensing mechanism is proposed.

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 227
Author(s):  
Qichao Li ◽  
Yamin Liu ◽  
Di Chen ◽  
Jianmin Miao ◽  
Xiao Zhi ◽  
...  

High-performance tracking trace amounts of NO2 with gas sensors could be helpful in protecting human health since high levels of NO2 may increase the risk of developing acute exacerbation of chronic obstructive pulmonary disease. Among various gas sensors, Graphene-based sensors have attracted broad attention due to their sensitivity, particularly with the addition of noble metals (e.g., Ag). Nevertheless, the internal mechanism of improving the gas sensing behavior through doping Ag is still unclear. Herein, the impact of Ag doping on the sensing properties of Graphene-based sensors is systematically analyzed via first principles. Based on the density-functional theory (DFT), the adsorption behavior of specific gases (NO2, NH3, H2O, CO2, CH4, and C2H6) on Ag-doped Graphene (Ag–Gr) is calculated and compared. It is found that NO2 shows the strongest interaction and largest Mulliken charge transfer to Ag–Gr among these studied gases, which may directly result in the highest sensitivity toward NO2 for the Ag–Gr-based gas sensor.


Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Sheng-Po Chang ◽  
Ren-Hao Yang ◽  
Chih-Hung Lin

InTiZnO gas sensors with different oxygen ratios were fabricated by RF sputtering at room temperature. The sensing responses for five different gases, including ethanol, isopropanol (IPA), acetone (ACE), CO, and SO2, were reported. The InTiZnO gas sensor with the MSM (metal–semiconductor–metal) structure generated a higher sensing response when the O2/Ar ratio was increased to 10%. It also revealed high selectivity among these gases and good repeatability. Moreover, the UV light-activated InTiZnO gas sensors were also studied, which could reduce the operating temperature from 300 °C to 150 °C and did not seem to damage the sensing film, demonstrating long-term stability. The high response and selectivity revealed that InTiZnO thin films possess high potential to be applied in gas sensing technology.


2021 ◽  
Vol 9 ◽  
Author(s):  
Zongtao Ma ◽  
Ziying Wang ◽  
Lingxiao Gao

In recent years, gas sensing electronic devices have always attracted wide attention in the field of environment, industry, aviation and others. In order to improve the gas sensing properties, many micro- and nano-fabrication technologies have been proposed and investigated to develop high-performance gas sensing devices. It is worth noting that light irradiation is an effective strategy to enhance gas sensitivity, shorten the response and recovery time, reduce operating temperature. In this review, firstly, the latest research advances of gas sensors based on different micro-nanostructure materials under UV light and visible light activation is introduced. Then, the gas sensing mechanism of light-assisted gas sensor is discussed in detail. Finally, this review describes the present application of gas sensors with improved properties under light activation assisted conditions and the perspective of their applications.


2020 ◽  
Author(s):  
jiamu cao ◽  
jing zhou ◽  
jianing shi ◽  
yufeng zhang ◽  
junyu chen ◽  
...  

Abstract Owing to their harmful and polluting the environment, nitrogen oxides and sulfur dioxide are expected to monitor when they are used. However, the widespread use of gas sensing methods presents obstacles in terms of portability or stability. Hence, a better detect way needs to be found urgently. The success of graphene-based gas sensors has stimulated interest in two-dimensional (2D) materials in the gas sensing area. Transition metal dichalcogenides (TMDs), such as MoS2 or WS2, are considered to have the high-performance potential for gas sensors. Unfortunately, when used as a gas sensor, the sensing response of the pristine TMDs is greatly affected by a number of gas molecules that are too weak to be detected. Herein, to evaluate the sensing capability of Al, P, and Fe-doped WS2 to NO, NO2, and SO2, the molecular model of the adsorption systems was constructed, and density functional theory (DFT) was used to calculate the adsorption behavior of these gases. The binding force of all the doped-WS2 to the harmful gas molecules is much stronger than that of the pristine WS2. According to the results of adsorption energy, band structure, and state density, Al-doped WS2 has the potential to be used as NO and SO2 gas sensor, while P-doped WS2 is selective to NO. This work opens up a new reference for choosing appropriate doping types on 2D materials for noxious gas sensing.


Author(s):  
Mateusz Kotarski ◽  
Janusz Smulko

Taguchi gas sensors are commonly used to measure gas concentration. The standard detection method utilizes only changes of sensor DC resistance to determine various gases concentration. Unfortunately, such technique leads to false results due to cross-sensitivity of gas sensors at presence of other gases. Such adverse effects can be reduced by applying fluctuation enhanced sensing and temperature modulation of the sensor what allows to gather more information about ambient atmosphere than the sensor DC resistance only. The measurement setup of voltage fluctuations across the gas sensor as well as the selected measurements results of DC resistance under temperature modulation are presented. New indicators of gas detection have been proposed which utilize voltage fluctuations and DC resistance measurements at two selected different temperatures of the gas sensor.


Author(s):  
Priya Gupta ◽  
Savita Maurya ◽  
Narendra Kumar Pandey ◽  
Vernica Verma

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.


Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 783 ◽  
Author(s):  
Andrea Gaiardo ◽  
David Novel ◽  
Elia Scattolo ◽  
Michele Crivellari ◽  
Antonino Picciotto ◽  
...  

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.


Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 202
Author(s):  
Yexin Dai ◽  
Jie Ding ◽  
Jingyu Li ◽  
Yang Li ◽  
Yanping Zong ◽  
...  

In this work, reduced graphene oxide (rGO) nanocomposites doped with nitrogen (N), sulfur (S) and transitional metal (Ni, Co, Fe) were synthesized by using a simple one-step in-situ hydrothermal approach. Electrochemical characterization showed that rGO-NS-Ni was the most prominent catalyst for glucose oxidation. The current density of the direct glucose alkaline fuel cell (DGAFC) with rGO-NS-Ni as the anode catalyst reached 148.0 mA/cm2, which was 40.82% higher than the blank group. The DGAFC exhibited a maximum power density of 48 W/m2, which was more than 2.08 folds than that of blank group. The catalyst was further characterized by SEM, XPS and Raman. It was speculated that the boosted performance was due to the synergistic effect of N, S-doped rGO and the metallic redox couples, (Ni2+/Ni3+, Co2+/Co3+ and Fe2+/Fe3+), which created more active sites and accelerated electron transfer. This research can provide insights for the development of environmental benign catalysts and promote the application of the DGAFCs.


Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 3947
Author(s):  
Wei Wang ◽  
Qinyi Zhang ◽  
Ruonan Lv ◽  
Dong Wu ◽  
Shunping Zhang

High performance formaldehyde gas sensors are widely needed for indoor air quality monitoring. A modified layer of zeolite on the surface of metal oxide semiconductors results in selectivity improvement to formaldehyde as gas sensors. However, there is insufficient knowledge on how the thickness of the zeolite layer affects the gas sensing properties. In this paper, ZSM-5 zeolite films were coated on the surface of the SnO2 gas sensors by the screen printing method. The thickness of ZSM-5 zeolite films was controlled by adjusting the numbers of screen printing layers. The influence of ZSM-5 film thickness on the performance of ZSM-5/SnO2 gas sensors was studied. The results showed that the ZSM-5/SnO2 gas sensors with a thickness of 19.5 μm greatly improved the selectivity to formaldehyde, and reduced the response to ethanol, acetone and benzene at 350 °C. The mechanism of the selectivity improvement to formaldehyde of the sensors was discussed.


Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 372
Author(s):  
Liyang Lin ◽  
Susu Chen ◽  
Tao Deng ◽  
Wen Zeng

The metal oxides/graphene nanocomposites have great application prospects in the fields of electrochemical energy storage and gas sensing detection. However, rational synthesis of such materials with good conductivity and electrochemical activity is the topical challenge for high-performance devices. Here, SnO2/graphene nanocomposite is taken as a typical example and develops a universal synthesis method that overcome these challenges and prepares the oxygen-deficient SnO2 hollow nanospheres/graphene (r-SnO2/GN) nanocomposite with excellent performance for supercapacitors and gas sensors. The electrode r-SnO2/GN exhibits specific capacitance of 947.4 F g−1 at a current density of 2 mA cm−2 and of 640.0 F g−1 even at 20 mA cm−2, showing remarkable rate capability. For gas-sensing application, the sensor r-SnO2/GN showed good sensitivity (~13.8 under 500 ppm) and short response/recovering time toward methane gas. These performance features make r-SnO2/GN nanocomposite a promising candidate for high-performance energy storage devices and gas sensors.


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