SnO2Nanostructure as Pollutant Gas Sensors: Synthesis, Sensing Performances, and Mechanism

A significant amount of pollutants is produced from factories and motor vehicles in the form of gas. Their negative impact on the environment is well known; therefore detection with effective gas sensors is important as part of pollution prevention efforts. Gas sensors use a metal oxide semiconductor, specifically SnO2nanostructures. This semiconductor is interesting and worthy of further investigation because of its many uses, for example, as lithium battery electrode, energy storage, catalyst, and transistor, and has potential as a gas sensor. In addition, there has to be a discussion of the use of SnO2as a pollutant gas sensor especially for waste products such as CO, CO2, SO2, and NOx. In this paper, the development of the fabrication of SnO2nanostructures synthesis will be described as it relates to the performances as pollutant gas sensors. In addition, the functionalization of SnO2as a gas sensor is extensively discussed with respect to the theory of gas adsorption, the surface features of SnO2, the band gap theory, and electron transfer.

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Field Study of Metal Oxide Semiconductor Gas Sensors in Temperature Cycled Operation for Selective VOC Monitoring in Indoor Air

Atmosphere ◽

10.3390/atmos12050647 ◽

2021 ◽

Vol 12 (5) ◽

pp. 647

Author(s):

Tobias Baur ◽

Johannes Amann ◽

Caroline Schultealbert ◽

Andreas Schütze

Keyword(s):

Air Quality ◽

Metal Oxide ◽

Gas Sensor ◽

Gas Sensors ◽

Indoor Air ◽

Ambient Air ◽

Quantitative Agreement ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

High Temporal Resolution

More and more metal oxide semiconductor (MOS) gas sensors with digital interfaces are entering the market for indoor air quality (IAQ) monitoring. These sensors are intended to measure volatile organic compounds (VOCs) in indoor air, an important air quality factor. However, their standard operating mode often does not make full use of their true capabilities. More sophisticated operation modes, extensive calibration and advanced data evaluation can significantly improve VOC measurements and, furthermore, achieve selective measurements of single gases or at least types of VOCs. This study provides an overview of the potential and limits of MOS gas sensors for IAQ monitoring using temperature cycled operation (TCO), calibration with randomized exposure and data-based models trained with advanced machine learning. After lab calibration, a commercial digital gas sensor with four different gas-sensitive layers was tested in the field over several weeks. In addition to monitoring normal ambient air, release tests were performed with compounds that were included in the lab calibration, but also with additional VOCs. The tests were accompanied by different analytical systems (GC-MS with Tenax sampling, mobile GC-PID and GC-RCP). The results show quantitative agreement between analytical systems and the MOS gas sensor system. The study shows that MOS sensors are highly suitable for determining the overall VOC concentrations with high temporal resolution and, with some restrictions, also for selective measurements of individual components.

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Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics

Sensors ◽

10.3390/s21062103 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2103 ◽

Cited By ~ 1

Author(s):

Tae-Hee Han ◽

So-Young Bak ◽

Sangwoo Kim ◽

Se Hyeong Lee ◽

Ye-Ji Han ◽

...

Keyword(s):

Gas Sensor ◽

Gas Sensors ◽

Sol Gel ◽

Oxide Semiconductor ◽

Zno Nps ◽

X Ray ◽

Semiconductor Gas Sensor ◽

Initial Resistance ◽

P Type ◽

Sensing Characteristics

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

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Calibration of Metal Oxide Semiconductor Gas Sensors by High School Students

International Journal of Online and Biomedical Engineering (iJOE) ◽

10.3991/ijoe.v17i04.19215 ◽

2021 ◽

Vol 17 (04) ◽

pp. 4

Author(s):

Sebastian Höfner ◽

Andreas Schütze ◽

Michael Hirth ◽

Jochen Kuhn ◽

Benjamin Brück

Keyword(s):

High School Students ◽

Air Quality ◽

Metal Oxide ◽

Gas Sensor ◽

Gas Sensors ◽

Objective Assessment ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

Calibration Process ◽

Wide Range

A wide range of pollutants cannot be perceived with human senses, which is why the use of gas sensors is indispensable for an objective assessment of air quality. Since many pollutants are both odorless and colorless, there is a lack of awareness, in particular among students. The project SUSmobil (funded by DBU – Deutsche Bundesstiftung Umwelt) aims to change this. In three modules on the topic of gas sensors and air quality, the students (a) learn the functionality of a metal oxide semiconductor (MOS) gas sensor, (b) perform a calibration process and (c) carry out environmental measurements with calibrated sensors. Based on these introductory experiments, the students are encouraged to develop their own environmental questions. In this paper, the student experiment for the calibration of a MOS gas sensor for ethanol is discussed. The experiment, designed as an HTML-based learning, addresses both theoretical and practical aspects of a typical sensor calibration process, consisting of data acquisition, feature extraction and model generation. In this example, machine learning is used for generating the evaluation model as existing physical models are not sufficiently exact.

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Modeling of the Function Principle of Semiconductor Gas Sensors for High School Students

International Journal of Online and Biomedical Engineering (iJOE) ◽

10.3991/ijoe.v17i03.19213 ◽

2021 ◽

Vol 17 (03) ◽

pp. 5

Author(s):

Sebastian Höfner ◽

Michael Hirth ◽

Jochen Kuhn ◽

Benjamin Brück ◽

Andreas Schütze

Keyword(s):

High School ◽

High School Students ◽

Air Quality ◽

Gas Sensor ◽

Gas Sensors ◽

Objective Assessment ◽

Oxide Semiconductor ◽

Sensor Calibration ◽

School Students ◽

Wide Range

A wide range of pollutants cannot be perceived with human senses, which is why theuse of gas sensors is indispensable for an objective assessment of air quality. Sincemany pollutants are both odorless and colorless, there is a lack of awareness, inparticular among high school students. The project SUSmobil (funded by DBU –Deutsche Bundesstiftung Umwelt) aims to change this. In three modules on the topic ofgas sensors and air quality, the students (1) are familiarized with the functionality of ametal oxide semiconductor (MOS) gas sensor, (2) perform a sensor calibration and (3)carry out environmental measurements with calibrated sensors. Based on theseintroductory experiments, the students are encouraged to develop their ownenvironmental questions. In this contribution, we focus on the experimental andmodeling approach which explains the function principle of a MOS gas sensor in a waysuitable for high school students. This includes a qualitative and quantitativedescription of a simplified sensor model explaining the main processes on the sensorsurface. In addition, an HTML-based self-learning course is presented in which thestudents investigate the sensor behavior in the presence of different substancesdepending on the sensor temperature.

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Random gas mixtures for efficient gas sensor calibration

Journal of Sensors and Sensor Systems ◽

10.5194/jsss-9-411-2020 ◽

2020 ◽

Vol 9 (2) ◽

pp. 411-424

Author(s):

Tobias Baur ◽

Manuel Bastuck ◽

Caroline Schultealbert ◽

Tilman Sauerwald ◽

Andreas Schütze

Keyword(s):

Air Quality ◽

Gas Sensor ◽

Gas Sensors ◽

Gas Mixtures ◽

Machine Learning Algorithms ◽

Oxide Semiconductor ◽

Sensor Calibration ◽

Successful Implementation ◽

Sensor Systems ◽

Calibration Scheme

Abstract. Applications like air quality, fire detection and detection of explosives require selective and quantitative measurements in an ever-changing background of interfering gases. One main issue hindering the successful implementation of gas sensors in real-world applications is the lack of appropriate calibration procedures for advanced gas sensor systems. This article presents a calibration scheme for gas sensors based on statistically distributed gas profiles with unique randomized gas mixtures. This enables a more realistic gas sensor calibration including masking effects and other gas interactions which are not considered in classical sequential calibration. The calibration scheme is tested with two different metal oxide semiconductor sensors in temperature-cycled operation using indoor air quality as an example use case. The results are compared to a classical calibration strategy with sequentially increasing gas concentrations. While a model trained with data from the sequential calibration performs poorly on the more realistic mixtures, our randomized calibration achieves significantly better results for the prediction of both sequential and randomized measurements for, for example, acetone, benzene and hydrogen. Its statistical nature makes it robust against overfitting and well suited for machine learning algorithms. Our novel method is a promising approach for the successful transfer of gas sensor systems from the laboratory into the field. Due to the generic approach using concentration distributions the resulting performance tests are versatile for various applications.

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Improving Gas-Sensing Performance Based on MOS Nanomaterials: A Review

Materials ◽

10.3390/ma14154263 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4263

Author(s):

Shirui Xue ◽

Sicheng Cao ◽

Zhaoling Huang ◽

Daoguo Yang ◽

Guoqi Zhang

Keyword(s):

Gas Sensors ◽

Agricultural Production ◽

Gas Adsorption ◽

Gas Sensing ◽

High Sensitivity ◽

Oxide Semiconductor ◽

Sensing Properties ◽

Advantages And Disadvantages ◽

Short Recovery Time ◽

Gas Sensing Properties

In order to solve issues of air pollution, to monitor human health, and to promote agricultural production, gas sensors have been used widely. Metal oxide semiconductor (MOS) gas sensors have become an important area of research in the field of gas sensing due to their high sensitivity, quick response time, and short recovery time for NO2, CO2, acetone, etc. In our article, we mainly focus on the gas-sensing properties of MOS gas sensors and summarize the methods that are based on the interface effect of MOS materials and micro–nanostructures to improve their performance. These methods include noble metal modification, doping, and core-shell (C-S) nanostructure. Moreover, we also describe the mechanism of these methods to analyze the advantages and disadvantages of energy barrier modulation and electron transfer for gas adsorption. Finally, we put forward a variety of research ideas based on the above methods to improve the gas-sensing properties. Some perspectives for the development of MOS gas sensors are also discussed.

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ANALYSIS OF MEASURES TO REDUCE ECOLOGICAL AND ECONOMIC DAMAGE FROM AUTOMOBILE TRANSPORT

STATE AND DEVELOPMENT PROSPECTS OF AGRIBUSINESS. In the frame of the XXIII Agribusiness Forum of the South of Russia and the Exhibition «Interagromash» Volume 1 ◽

10.23947/interagro.2020.1.643-646 ◽

2020 ◽

Author(s):

V.N. Kurdyukov ◽

◽

T.V. Lebedeva ◽

Keyword(s):

Resource Allocation ◽

Negative Impact ◽

The State ◽

Point Of View ◽

Motor Vehicles ◽

Economic Damage ◽

Agriculture Education

The article considers common classifications of measures to reduce environmentaleconomic damage from motor vehicles. Classification from the point of view of control impact is proposed, which allows to take into account relations between the state and citizens in the field of reduction of negative impact of motor vehicles on the environment. The analysis of the classification made it possible to identify areas of activity for improving the efficiency of management impacts, taking into account the incentives of citizens to comply with the requirements of the legislation and to create conditions for their exceeding. Increasing the efficiency of resource allocation in the Territory will allow the released funds to be allocated to the development of industry, agriculture, education and science.

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Metal-oxide based ammonia gas sensors: A review

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681210999200718005402 ◽

2020 ◽

Vol 10 ◽

Author(s):

Priya Gupta ◽

Savita Maurya ◽

Narendra Kumar Pandey ◽

Vernica Verma

Keyword(s):

Metal Oxide ◽

Metal Oxides ◽

Gas Sensor ◽

Gas Sensors ◽

Review Paper ◽

Gas Sensing ◽

Gas Sensitivity ◽

Ammonia Gas ◽

Ammonia Sensing ◽

Ammonia Gas Sensors

: 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.

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