Janusz Marek Smulko, Maciej Trawka, Claes Goran Granqvist, Radu Ionescu, Fatima Annanouch, Eduard Llobet and Laszlo Bela Kish
– This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors.
Abstract
Purpose
This paper aims to present the methods of improving selectivity and sensitivity of resistance gas sensors.
Design/methodology/approach
This paper compares various methods of improving gas sensing by temperature modulation, UV irradiation or fluctuation-enhanced sensing. The authors analyze low-frequency resistance fluctuations in commercial Taguchi gas sensors and the recently developed tungsten trioxide (WO3) gas-sensing layers, exhibiting a photo-catalytic effect.
Findings
The efficiency of using low-frequency fluctuations to improve gas detection selectivity and sensitivity was confirmed by numerous experimental studies in commercial and prototype gas sensors.
Research limitations/implications
A more advanced measurement setup is required to record noise data but it will reduce the number of gas sensors necessary for identifying the investigated gas mixtures.
Practical implications
Fluctuation-enhanced sensing can reduce the energy consumption of gas detection systems and assures better detection results.
Originality/value
A thorough comparison of various gas sensing methods in resistance gas sensors is presented and supported by exemplary practical applications.
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A. Zielinski, J. Smulko, A. Krakowiak and K. Darowicki
The results of the electrochemical noise observations in 0H18N9 steel are presented. Current noise was obtained by potentiostatic measurements in aqueous solution of 0.1M H2SO4…
Abstract
The results of the electrochemical noise observations in 0H18N9 steel are presented. Current noise was obtained by potentiostatic measurements in aqueous solution of 0.1M H2SO4 and 0.06M Cl−. The recorded noise had an evident trend and peaks that are typically observed during pitting corrosion. The trend was removed by means of the third order polynomial approximation. The statistical hypothesis, i.e. the difference between the approximation and the observed noise, was tested. The results confirmed that current noise caused by pitting corrosion has nonstationary or weakly stationary character. The recorded noise was analysed using the Joint Time‐Frequency Analysis method, which is appropriate for nonstationary signals. The derived results confirmed the presence of pitting corrosion. It was usual for a few pits to form on the surface of the electrodes in distinct phases, and these were observed as peaks in current fluctuations.
Hui Li, Zhihui Gao, Weihao Lin, Wei He, Jinyan Li and Yong Yang
Graphene is a two-dimensional material. Its use has many advantages in gas sensing, but its long desorption process is problematic. The aim of this paper is to design a…
Abstract
Purpose
Graphene is a two-dimensional material. Its use has many advantages in gas sensing, but its long desorption process is problematic. The aim of this paper is to design a graphene-based gas sensor, study the response to NO2 gas concentrations and find ways to accelerate the desorption process.
Design/methodology/approach
In one group, the sensor was placed in air to measure its initial resistance. Then, it was exposed to the NO2 gas at a certain concentration. Finally, the sensor was exposed to light immediately after NO2 gas exposure was ended. In another group, the sensor was heated using a heating plate at a stable temperature, before taking the measurements. Then the adsorption and desorption experiments were carried on.
Findings
Illumination and heating at a suitable temperature can expedite desorption of NO2 molecules on graphene.
Originality/value
In the paper, two main methods are introduced to accelerate the desorption process when the NO2 gas is absorbed on graphene. Through a series of experiments and analysis, the authors found that the recovery time could be reduced observably and the recovery performance of the graphene-based NO2 sensor could be improved effectively.
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Saeed Reza Allahkaram and Namdar Mohammadi
This paper aims to evaluate corrosion behavior of bare and PbO2-coated stainless steel 316L, as prospective candidates for bipolar plates, in simulated proton exchange membrane…
Abstract
Purpose
This paper aims to evaluate corrosion behavior of bare and PbO2-coated stainless steel 316L, as prospective candidates for bipolar plates, in simulated proton exchange membrane fuel cell’s (PEMFC’s) environment under operating potentials.
Design/methodology/approach
A set of potentiodynamic, as well as potentiostatic, electrochemical experiments was carried out under both anodic and cathodic potentials. Gathered data were analyzed via fast Fourier transform algorithm for further investigation. X-ray diffraction analysis was also used for determining coating characteristics upon completion of electrochemical experiments.
Findings
Results revealed that bare SS316L is a better candidate for bipolar plate material under anodic potential, as it is cathodically protected. However, PbO2-coated SS316L is favorable under cathodic potential, as bare specimen will suffer localized corrosion in the form of pitting.
Research limitations/implications
It would be of interest if all the experiments are carried out in a PEMFC stack.
Practical implications
This research strives to promote the use of electrochemical noise measurement for practical corrosion monitoring of coated bipolar plates in fuel cells.
Social implications
Improving the corrosion resistance of bipolar plates will expedite commercialization of PEMFCs, which in turn will translate into a substantial reduction in carbon footprint.
Originality/value
This research strives to promote the use of electrochemical noise measurement for practical corrosion monitoring of coated bipolar plates in fuel cells.
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Lei Ren, Guolin Cheng, Wei Chen, Pei Li and Zhenhe Wang
This paper aims to explore recent advances in drift compensation algorithms for Electronic Nose (E-nose) technology and addresses sensor drift challenges through offline, online…
Abstract
Purpose
This paper aims to explore recent advances in drift compensation algorithms for Electronic Nose (E-nose) technology and addresses sensor drift challenges through offline, online and neural network-based strategies. It offers a comprehensive review and covers causes of drift, compensation methods and future directions. This synthesis provides insights for enhancing the reliability and effectiveness of E-nose systems in drift issues.
Design/methodology/approach
The article adopts a comprehensive approach and systematically explores the causes of sensor drift in E-nose systems and proposes various compensation strategies. It covers both offline and online compensation methods, as well as neural network-based approaches, and provides a holistic view of the available techniques.
Findings
The article provides a comprehensive overview of drift compensation algorithms for E-nose technology and consolidates recent research insights. It addresses challenges like sensor calibration and algorithm complexity, while discussing future directions. Readers gain an understanding of the current state-of-the-art and emerging trends in electronic olfaction.
Originality/value
This article presents a comprehensive review of the latest advancements in drift compensation algorithms for electronic nose technology and covers the causes of drift, offline drift compensation algorithms, online drift compensation algorithms and neural network drift compensation algorithms. The article also summarizes and discusses the current challenges and future directions of drift compensation algorithms in electronic nose systems.
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Ziyan Wang, Xueli Yang, Caixuan Sun, Hongyan Liu, Junkai Shao, Mengjie Wang, Junyi Dong, Guanlong Cao and Guofeng Pan
This paper aims to successfully synthesize three-dimensional spindle-like Au functionalized Co3O4-ZnO nanocomposites; characterize the structure, morphology and surface chemical…
Abstract
Purpose
This paper aims to successfully synthesize three-dimensional spindle-like Au functionalized Co3O4-ZnO nanocomposites; characterize the structure, morphology and surface chemical properties of the products; study the effect of Au NPs doping concentration, operating temperature different gas to, sensing properties; and introduce an attractive gas sensor for acetone detection.
Design/methodology/approach
Au NPs functionalized Co3O4-ZnO nanocomposite was prepared by coprecipitation and impregnation methods; the structure and surface chemical property of the products were characterized by XRD, SEM, TEM, UV-Vis, BET and XPS. The sensing ability of Au@Co3O4-ZnO for acetone and mechanism was analyzed systematically.
Findings
The results of gas sensing tests show that the unique component structure, Schottky junction and catalytic effect of Au functionalization make it have low operating temperature, excellent selectivity, high response (10 ppm, 56) and rapid response recovery time.
Research limitations/implications
All the characterization and test data of the prepared materials are provided in this paper and reveals the gas sensing mechanism of the gas sensor.
Practical implications
The detection limit is 2.92–100 ppb acetone. It is promising to be applied in low-power, micro detection and miniature acetone gas sensors.
Social implications
The gas sensor prepared has a lower working temperature and low detection limit, so it has promising application prospects in low-concentration acetone detection and early warning.
Originality/value
The unique component structure, Schottky junction and catalytic effect of Au functionalization Co3O4-ZnO make it have low operating temperature, excellent selectivity and rapid response recovery time.
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This study aims to investigate the individual electrochemical transients arising from local anodic events on stainless steel, to uncover the potential mechanisms producing…
Abstract
Purpose
This study aims to investigate the individual electrochemical transients arising from local anodic events on stainless steel, to uncover the potential mechanisms producing different types of transients and to derive appropriate parameters indicative of the corrosion severity of such transient events.
Design/methodology/approach
An equivalent circuit model was used for the transient analysis, which was performed using a local current allocation rule based on the relative instant cathodic resistance of the coupled electrodes, as well as the kinetic parameters derived from the electrochemical polarization measurement.
Findings
The shape and size of the electrochemical current transients arising from SS 316 L were influenced by the film stability, local anodic dissolution kinetics and the symmetry of the cathodic kinetics between the coupled electrodes, where the ultralong transient might correspond to the propagation of film damage with a slow anodic dissolution rate. The dynamic cathodic resistance during the final stage of transient current growth can serve as a characteristic parameter that reflects the loss of passive film protection.
Originality/value
Estimation of the local anodic current trace opens a new way for individual electrochemical transient analysis associated with the charges involved, local current densities and changes in film resistance throughout localized corrosion processes.
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Naing Naing Aung, Wong Keng Wai and Yong‐Jun Tan
The objective of this work was to develop practical experimental techniques for monitoring corrosion in “difficult‐to‐test” conditions such as corrosion under insulation (CUI).
Abstract
Purpose
The objective of this work was to develop practical experimental techniques for monitoring corrosion in “difficult‐to‐test” conditions such as corrosion under insulation (CUI).
Design/methodology/approach
An electrochemically integrated multi‐electrode array namely the wire beam electrode (WBE) method has been used in combination with noise signature analysis for the first time to monitor the penetration of corrosive species under simulated corrosion‐under‐insulation conditions. Corrosion of aluminium exposed under insulation materials such as rock wool, glass wool, cotton wool and tissue paper has been successfully monitored.
Findings
A typical potential noise signature of a major potential jump from AA1100 WBE was observed which corresponded to the corrosive species reaching the WBE surface in WBE current distribution map. A good correlation between the galvanic current maps and the corroded surface was also observed.
Originality/value
The preliminary results suggest that the proposed novel electrochemical method is capable of monitoring CUI.