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Ilyas F, Fazal H, Ahmed M, Iqbal A, Ishaq M, Jabeen M, Butt M, Farid S. Advances in ionic liquids as fluorescent sensors. CHEMOSPHERE 2024; 352:141434. [PMID: 38401867 DOI: 10.1016/j.chemosphere.2024.141434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/08/2024] [Accepted: 02/08/2024] [Indexed: 02/26/2024]
Abstract
Ionic liquids (ILs) are a class of liquid salts with characteristics such as a low melting point, an ionic nature, non-volatility, and tunable properties. Because of their adaptability, they have a significant influence in the field of fluorescence. This paper reviews the primary literature on the use of ILs in fluorescence sensing technologies. The kind of target material is utilized to classify the fluorescence sensors made with the use of ILs. They include using ILs as probes for metals, nitro explosives, small organic compounds, anions, and gases. The efficacy of an IL-based fluorescence sensor depends on the precise design to guarantee specificity, sensitivity, and a consistent reaction to the desired analyte. The precise method can differ depending on the chemical properties of the IL, the choice of fluorophore, and the interactions with the analyte. Overall, the viability of the aforementioned materials for chemical analysis is evaluated, and prospective possibilities for further development are identified.
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Affiliation(s)
- Farva Ilyas
- Department of Materials Science and Engineering, College of Transportation Engineering, Dalian Maritime University, Dalian, 116026, China; Shanghai Jiao Tong University, Shanghai, 200240, China.
| | - Hira Fazal
- Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Muhktiar Ahmed
- Chemistry of Interfaces, Luleå University of Technology, SE-97 187, Luleå, Sweden
| | - Asma Iqbal
- Shanghai Jiao Tong University, Shanghai, 200240, China
| | | | - Maher Jabeen
- Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Madiha Butt
- Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Sumbal Farid
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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2
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Baharfar M, Lin J, Kilani M, Zhao L, Zhang Q, Mao G. Gas nanosensors for health and safety applications in mining. NANOSCALE ADVANCES 2023; 5:5997-6016. [PMID: 37941945 PMCID: PMC10629029 DOI: 10.1039/d3na00507k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
The ever-increasing demand for accurate, miniaturized, and cost-effective gas sensing systems has eclipsed basic research across many disciplines. Along with the rapid progress in nanotechnology, the latest development in gas sensing technology is dominated by the incorporation of nanomaterials with different properties and structures. Such nanomaterials provide a variety of sensing interfaces operating on different principles ranging from chemiresistive and electrochemical to optical modules. Compared to thick film and bulk structures currently used for gas sensing, nanomaterials are advantageous in terms of surface-to-volume ratio, response time, and power consumption. However, designing nanostructured gas sensors for the marketplace requires understanding of key mechanisms in detecting certain gaseous analytes. Herein, we provide an overview of different sensing modules and nanomaterials under development for sensing critical gases in the mining industry, specifically for health and safety monitoring of mining workers. The interactions between target gas molecules and the sensing interface and strategies to tailor the gas sensing interfacial properties are highlighted throughout the review. Finally, challenges of existing nanomaterial-based sensing systems, directions for future studies, and conclusions are discussed.
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Affiliation(s)
- Mahroo Baharfar
- School of Chemical Engineering, University of New South Wales (UNSW Sydney) Sydney New South Wales 2052 Australia
| | - Jiancheng Lin
- School of Chemical Engineering, University of New South Wales (UNSW Sydney) Sydney New South Wales 2052 Australia
| | - Mohamed Kilani
- School of Chemical Engineering, University of New South Wales (UNSW Sydney) Sydney New South Wales 2052 Australia
| | - Liang Zhao
- Azure Mining Technology Pty Ltd Sydney New South Wales 2067 Australia
| | - Qing Zhang
- CCTEG Changzhou Research Institute Changzhou 213015 China
| | - Guangzhao Mao
- School of Chemical Engineering, University of New South Wales (UNSW Sydney) Sydney New South Wales 2052 Australia
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3
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Huang X, Li Y, Witherspoon E, He R, Petruncio G, Paige M, Li M, Liu T, Amine K, Wang Z, Li Q, Dong P. Species-Selective Detection of Volatile Organic Compounds by Ionic Liquid-Based Electrolyte Using Electrochemical Methods. ACS Sens 2023; 8:3389-3399. [PMID: 37589910 DOI: 10.1021/acssensors.3c00578] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
The detection of volatile organic compounds (VOCs) is an important topic for environmental safety and public health. However, the current commercial VOC detectors suffer from cross-sensitivity and low reproducibility. In this work, we present species-selective detection for VOCs using an electrochemical cell based on ionic liquid (IL) electrolytes with features of high selectivity and reliability. The voltammograms measured with the IL-based electrolyte absorbing different VOCs exhibited species-selective features that were extracted and classified by linear discriminant analysis (LDA). The detection system could identify as many as four types of VOCs, including methanol, ethanol, acetone, formaldehyde, and additional water. A mixture of methanol and formaldehyde was detected as well. The sample required for the VOCs classification system was 50 μL, or 1.164 mmol, on average. The response time for each VOC measurement is as fast as 24 s. The volume of VOCs such as formaldehyde in solution could also be quantified by LDA and electrochemical impedance spectroscopy techniques, respectively. The system showed a tunable detection range for 1.6 and 16% (w/v) CH2O solution by adjusting the composition of the electrolyte. The limit of detection was as low as 1 μL. For the 1.6% CH2O solution, the linearity calibration range was determined to be from 5.30 to 53.00 μmol with a limit of detection at 0.53 μmol. The mechanisms for VOCs determination and quantification are also thoroughly discussed. It is expected that this work could provide a new insight into the concept of electrochemical detection of VOCs with machine learning analysis and be applied to both VOCs gas monitoring and fluid detection.
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Affiliation(s)
- Xiaozhou Huang
- Department of Mechanical Engineering, George Mason University, Fairfax, Virginia 22030 United States
- Department of Chemistry & Biochemistry, George Mason University, Manassas, Virginia 20110, United States
| | - Yaonian Li
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22030 United States
| | - Erin Witherspoon
- Department of Chemistry, Oakland University, Rochester Hills, Michigan 48309 United States
| | - Rui He
- Department of Mechanical Engineering, George Mason University, Fairfax, Virginia 22030 United States
| | - Greg Petruncio
- Department of Chemistry & Biochemistry, George Mason University, Manassas, Virginia 20110, United States
| | - Mikell Paige
- Department of Chemistry & Biochemistry, George Mason University, Manassas, Virginia 20110, United States
| | - Matthew Li
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Tongchao Liu
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Khalil Amine
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
- Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University (IAU), Dammam 34221, Saudi Arabia
| | - Zhe Wang
- Department of Chemistry, Oakland University, Rochester Hills, Michigan 48309 United States
| | - Qiliang Li
- Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22030 United States
| | - Pei Dong
- Department of Mechanical Engineering, George Mason University, Fairfax, Virginia 22030 United States
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4
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Wang R, Wu P, Zhi Z, Gao W, Hua Z. Amperometric hydrogen sensor based on pyrrolidinium hydrogen sulfate under anaerobic conditions. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2022. [DOI: 10.1016/j.cjac.2022.100065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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5
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Zhou M, Wang H. Optimally Selecting Photo- and Electrocatalysis to Facilitate CH 4 Activation on TiO 2(110) Surface: Localized Photoexcitation versus Global Electric-Field Polarization. JACS AU 2022; 2:188-196. [PMID: 35098235 PMCID: PMC8790734 DOI: 10.1021/jacsau.1c00466] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Indexed: 05/08/2023]
Abstract
Photo- and electrocatalytic technologies hold great promise for activating inert chemical bonds under mild conditions, but rationally selecting a more suitable method in between to maximize the performance remains an open issue, which requires a fundamental understanding of their different catalytic mechanisms. Herein, by first-principles calculations, we systematically compare the activation mechanisms for the C-H bond of the CH4 molecule on TiO2(110) under the photo- and electrocatalytic modes without or with water involved. It quantitatively reveals that the activation barrier of the C-H bond decreases dramatically with a surprising 74% scale by photoexcitation relative to that in thermocatalysis (1.12 eV), while the barrier varies with a maximum promotion of only 5% even under -1 V/Å external electric field (EEF). By detailed geometric/electronic analysis, the superior photocatalytic activity is traced to the highly oxidative lattice Obr •- radical excited by a photohole (h +), which motivates the homolytic C-H bond scission. However, under EEF from -1 V/Å to 1 V/Å, it gives a relatively mild charge polarization on the TiO2(110) surface region and thus a limited promotion for breaking the weakly polar C-H bond. By contrast, in the presence of water, we find that EEF can facilitate CH4 activation indirectly assisted by the surface radical-like OH* species from the oxidative water cleavage at high oxidative potential (>1.85 V vs SHE), which explains the high energy cost to drive electrocatalytic CH4 conversion in experiment. Alternatively, we demonstrate that more efficient CH4 activation could be also achieved at much lower oxidative potential when integrating the light irradiation. In such a circumstance, EEF can not only promote the h + accumulation at the catalyst surface but also help H2O deprotonation to form hydroxide, which can serve as an efficient hole-trapper to generate OH• radical (OH- + h + → OH•), unveiling an interesting synergistic photoelectrocatalytic effect. This work could provide a fundamental insight into the different characteristics of photo- and electrocatalysis in modulating chemical bond cleavage.
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6
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Indekeu A, Bailón-García E, Fernandes A, Baltazar R, Ferraria AM, do Rego AMB, Filipa Ribeiro M. Synthesis of modified TiO2-based catalysts for the photocatalytic production of solar fuels from synthesis gas. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.07.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
A chemiresistive sensor is described for the detection of methane (CH4), a potent greenhouse gas that also poses an explosion hazard in air. The chemiresistor allows for the low-power, low-cost, and distributed sensing of CH4 at room temperature in air with environmental implications for gas leak detection in homes, production facilities, and pipelines. Specifically, the chemiresistors are based on single-walled carbon nanotubes (SWCNTs) noncovalently functionalized with poly(4-vinylpyridine) (P4VP) that enables the incorporation of a platinum-polyoxometalate (Pt-POM) CH4 oxidation precatalyst into the sensor by P4VP coordination. The resulting SWCNT-P4VP-Pt-POM composite showed ppm-level sensitivity to CH4 and good stability to air as well as time, wherein the generation of a high-valent platinum intermediate during CH4 oxidation is proposed as the origin of the observed chemiresistive response. The chemiresistor was found to exhibit selectivity for CH4 over heavier hydrocarbons such as n-hexane, benzene, toluene, and o-xylene, as well as gases, including carbon dioxide and hydrogen. The utility of the sensor in detecting CH4 using a simple handheld multimeter was also demonstrated.
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8
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A Review of Methane Gas Detection Sensors: Recent Developments and Future Perspectives. INVENTIONS 2020. [DOI: 10.3390/inventions5030028] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Methane, the primary component of natural gas, is a significant contributor to global warming and climate change. It is a harmful greenhouse gas with an impact 28 times greater than carbon dioxide over a 100-year period. Preventing methane leakage from transmission pipelines and other oil and gas production activities is a possible solution to reduce methane emissions. In order to detect and resolve methane leaks, reliable and cost-effective sensors need to be researched and developed. This paper provides a comprehensive review of different types of methane detection sensors, including optical sensors, calorimetric sensors, pyroelectric sensors, semiconducting oxide sensors, and electrochemical sensors. The discussed material includes the definitions, mechanisms and recent developments of these sensors. A comparison between different methods, highlighting the advantages and disadvantages of each, is also presented to help address future research needs.
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9
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Tang Y, Liu X, McMahan J, Kumar A, Khan A, Sevilla M, Zeng X. Adsorption and Electrochemistry of Carbon Monoxide at the Ionic Liquid-Pt Interface. J Phys Chem B 2019; 123:4726-4734. [PMID: 31041862 DOI: 10.1021/acs.jpcb.8b11602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this work, CO adsorption and oxidation processes were studied with cyclic voltammetry and anodic adsorptive stripping chronoamperometry in two structural different ionic liquids (ILs) (i.e., 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [Bmpy][NTf2] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2]). Multiple redox processes were observed in the ILs. During the anodic oxidation processes, the NTf2- anion is oxidized to form NTf2• radical and CO is oxidized to CO2 and produces a proton in these ILs when a trace amount of water is present. The products of oxidation processes (NTf2• radical and proton) can be reduced at cathodic processes. Results show that the cation in these ILs can facilitate the formation of an electrolyte-electrode interface structure that influences the amount of CO adsorbed as well as the subsequent CO oxidation current and charge. By selecting the anodic and cathodic potentials, we developed an innovative electroanalytical method for CO sensing based on a simple double-potential adsorptive stripping chronoamperometry. The method allows calibration of the concurrent NTf2- anion and CO redox processes as well as the double-layer charging and discharging processes in the IL with the presence of a trace amount of water providing quantitative analysis of CO concentration with high accuracy and sensitivity. The reported method is the first work to show that quantitative CO detection can be achieved in the presence of complex dynamic interfacial processes in the ILs. The trace water present in the ILs is beneficial for CO oxidation, but a large amount of water is detrimental for the CO oxidation in ambient condition.
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Affiliation(s)
- Yongan Tang
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Xiaojun Liu
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Jordan McMahan
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Anil Kumar
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Asim Khan
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Michael Sevilla
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
| | - Xiangqun Zeng
- Department of Chemistry , Oakland University , Rochester , Michigan 48309 , United States
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10
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Goodchild SA, Hubble LJ, Mishra RK, Li Z, Goud KY, Barfidokht A, Shah R, Bagot KS, McIntosh AJS, Wang J. Ionic Liquid-Modified Disposable Electrochemical Sensor Strip for Analysis of Fentanyl. Anal Chem 2019; 91:3747-3753. [DOI: 10.1021/acs.analchem.9b00176] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Sarah A. Goodchild
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
- Defence Science
and Technology Laboratory, Porton Down, Salisbury SP4 0JQ, U.K
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K
| | - Lee J. Hubble
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
- CSIRO Manufacturing, Lindfield, New South Wales 2070, Australia
| | - Rupesh K. Mishra
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Zhanhong Li
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - K. Yugender Goud
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Abbas Barfidokht
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Rushabh Shah
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
| | - Kara S. Bagot
- Department of Psychiatry, University of California, San Diego, La Jolla, California 92093, United States
| | | | - Joseph Wang
- Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States
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11
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Dosi M, Lau I, Zhuang Y, Simakov DSA, Fowler MW, Pope MA. Ultrasensitive Electrochemical Methane Sensors Based on Solid Polymer Electrolyte-Infused Laser-Induced Graphene. ACS APPLIED MATERIALS & INTERFACES 2019; 11:6166-6173. [PMID: 30648868 DOI: 10.1021/acsami.8b22310] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Methane is a potent greenhouse gas, with large emissions occurring across gas distribution networks and mining/extraction infrastructure. The development of inexpensive, low-power electrochemical sensors could provide a cost-effective means to carry out distributed sensing to identify leaks for rapid mitigation. In this work, we demonstrate a simple and cost-effective strategy to rapidly prototype ultrasensitive electrochemical gas sensors. A room-temperature methane sensor is evaluated which demonstrates the highest reported sensitivity (0.55 μA/ppm/cm2) with a rapid response time (40 s) enabling sub-ppm detection. Porous, laser-induced graphene (LIG) electrodes are patterned directly into commercial polymer films and imbibed with a palladium nanoparticle dispersion to distribute the electrocatalyst within the high surface area support. A pseudo-solid-state ionic liquid/polyvinylidene fluoride electrolyte was painted onto the flexible cell yielding a porous electrolyte, within the porous LIG electrode, simultaneously facilitating rapid gas transport and enabling the room temperature electro-oxidation pathway for methane. The performance of the amperometric sensor is evaluated as a function of methane concentration, relative humidity, and tested against interfering gases.
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12
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Lin L, Zhao P, Mason AJ, Zeng X. Characterization of the Ionic Liquid/Electrode Interfacial Relaxation Processes Under Potential Polarization for Ionic Liquid Amperometric Gas Sensor Method Development. ACS Sens 2018; 3:1126-1134. [PMID: 29781608 PMCID: PMC7192316 DOI: 10.1021/acssensors.8b00155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electrochemical amperometric sensors require a constant or varying potential at the working electrode that drives redox reactions of the analyte for detection. The interfacial redox reaction(s) can result in the formation of new chemical products that could change the initial condition of the electrode/electrolyte interface. If the products are not inert and/or cannot be removed from the system such that the initial condition of the electrode/electrolyte interface cannot be restored, the sensor signal baseline would consequently drift, which is problematic for the continuous and real-time sensors. By setting the electrode potential with the periodical ON-OFF mode, electrolysis can be forestalled during the off mode which can minimize the sensor signal baseline drift and reduce the power consumption of the sensor. However, it is known that the relaxation of the structure in the electrical double layer at the ionic liquid/electrode interface to the steps of the electrode potential is slow. This work characterized the electrode/electrolyte interfacial relaxation process of an ionic liquid based electrochemical gas (IL-EG) sensor by performing multiple potential step experiments in which the potential is stepped from an open circuit potential (OCP) to the amperometric sensing potential at various frequencies with different time periods. Our results showed that by shortening the sensing period as well as extending the idle period (i.e., enlarge the ratio of idle period versus sensing period) of the potential step experiments, the electrode/electrolyte interface is prone to relax to its original state, and thus reduces the baseline drift. Additionally, the high viscosity of the ionic liquids is beneficial for electrochemical regeneration via the implementation of a conditioning step at zero volts at the electrode/electrolyte. By setting the working electrode at zero volts instead of OCP, our results showed that it could further minimize the baseline drift, enhance the sensing signal stability, and extend the functioning lifetime of a continuous IL-EG oxygen sensor.
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Affiliation(s)
- Lu Lin
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Peng Zhao
- Department of Mechanical Engineering, Oakland University, Rochester, Michigan 48309, United States
| | - Andrew J. Mason
- Department of Electrical Engineering and Computer Science, Michigan State University, East Lansing, Michigan 48824, United States
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
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Lin L, Zeng X. Toward continuous amperometric gas sensing in ionic liquids: rationalization of signal drift nature and calibration methods. Anal Bioanal Chem 2018; 410:4587-4596. [PMID: 29947905 DOI: 10.1007/s00216-018-1090-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/18/2018] [Accepted: 04/12/2018] [Indexed: 10/14/2022]
Abstract
Sensor signal drift is the key issue for the reliability of continuous gas sensors. In this paper, we characterized the sensing signal drift of an amperometric ionic liquid (IL)-based oxygen sensor to identify the key chemical parameters that contribute to the signal drift. The signal drifts due to the sensing reactions of the analyte oxygen at the electrode/electrolyte interface at a fixed potential and the mass transport of the reactant and product at the electrode/electrolyte interface were systematically studied. Results show that the analyte concentration variation and the platinum electrode surface activity are major factors contributing to sensing signal drift. An amperometric method with a double potential step incorporating a conditioning step was tested and demonstrated to be useful in reducing the sensing signal drift and extending the sensor operation lifetime. Also, a mathematic method was tested to calibrate the baseline drift and sensing signal sensitivity change for continuous sensing. This study provides the understanding of the chemical processes that contribute to the IL electrochemical gas (IL-EG) sensor signal stability and demonstrates some effective strategies for signal drift calibration that can increase the reliability of the continuous amperometric sensing. Graphical Abstract ᅟ.
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Affiliation(s)
- Lu Lin
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI, 48309, USA
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI, 48309, USA.
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14
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Wan H, Yin H, Lin L, Zeng X, Mason AJ. Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring. SENSORS AND ACTUATORS. B, CHEMICAL 2018. [PMID: 29255341 DOI: 10.1016/j.snb.2017.09.037] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.
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Affiliation(s)
- Hao Wan
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
| | - Heyu Yin
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
| | - Lu Lin
- Department of Chemistry, Oakland University, Rochester, MI, 48309, U.S.A
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, MI, 48309, U.S.A
| | - Andrew J Mason
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
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15
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Wan H, Yin H, Lin L, Zeng X, Mason AJ. Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring. SENSORS AND ACTUATORS. B, CHEMICAL 2018; 255:638-646. [PMID: 29255341 PMCID: PMC5731251 DOI: 10.1016/j.snb.2017.08.109] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.
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Affiliation(s)
- Hao Wan
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
| | - Heyu Yin
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
| | - Lu Lin
- Department of Chemistry, Oakland University, Rochester, MI, 48309, U.S.A
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, MI, 48309, U.S.A
| | - Andrew J. Mason
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI, 48824, U.S.A
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16
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Tang Y, He J, Gao X, Yang T, Zeng X. Continuous amperometric hydrogen gas sensing in ionic liquids. Analyst 2018; 143:4136-4146. [DOI: 10.1039/c8an00577j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Continuous and real-time ionic liquid based hydrogen gas sensor with high sensitivity, selectivity, speed, accuracy, repeatability and stability.
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Affiliation(s)
- Yongan Tang
- Department of Chemistry
- Oakland University
- Rochester
- USA
| | - Jianxin He
- Department of Computer Science
- The University of Iowa
- Iowa City
- USA
| | - Xiaoli Gao
- Department of Mathematics and Statistics
- University of North Carolina Greensboro
- USA
| | - Tianbao Yang
- Department of Computer Science
- The University of Iowa
- Iowa City
- USA
| | - Xiangqun Zeng
- Department of Chemistry
- Oakland University
- Rochester
- USA
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Fedorenko G, Oleksenko L, Maksymovych N, Skolyar G, Ripko O. Semiconductor Gas Sensors Based on Pd/SnO 2 Nanomaterials for Methane Detection in Air. NANOSCALE RESEARCH LETTERS 2017; 12:329. [PMID: 28476083 PMCID: PMC5418166 DOI: 10.1186/s11671-017-2102-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 04/24/2017] [Indexed: 05/19/2023]
Abstract
Semiconductor sensors based on nanosized Pd-containing tin dioxide have been obtained by a sol-gel technique. Semiconductor gas-sensitive materials were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods. Influence of Pd additives on sensitivity of the sensors to methane has been studied. Temperature dependences of electrical resistance in air and sensor response to methane on palladium content for the sensors based on nanosized materials Pd/SnO2 have been investigated.
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Affiliation(s)
- George Fedorenko
- Taras Shevchenko National University of Kyiv, 62a Volodymyrska str., Kyiv, 01601, Ukraine.
| | - Ludmila Oleksenko
- Taras Shevchenko National University of Kyiv, 62a Volodymyrska str., Kyiv, 01601, Ukraine
| | - Nelly Maksymovych
- Taras Shevchenko National University of Kyiv, 62a Volodymyrska str., Kyiv, 01601, Ukraine
| | - Galina Skolyar
- Taras Shevchenko National University of Kyiv, 62a Volodymyrska str., Kyiv, 01601, Ukraine
| | - Oleksandr Ripko
- Taras Shevchenko National University of Kyiv, 62a Volodymyrska str., Kyiv, 01601, Ukraine
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18
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Tang Y, Lin L, Kumar A, Guo M, Sevilla M, Zeng X. Hydrogen Electrooxidation in Ionic Liquids Catalyzed by the NTf 2 Radical. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:5161-5167. [PMID: 29071009 PMCID: PMC5651517 DOI: 10.1021/acs.jpcc.7b00335] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hydrogen electrooxidation via a "hydrogen abstraction" mechanism in an aprotic ionic liquid 1-butyl-1-methylpyrrolidinium bis-(trifluoromethylsulfonyl) [Bmpy][NTf2] under anaerobic conditions was investigated using cyclic voltammetry and density functional theory (DFT). It is found that a platinum bound NTf2 radical (NTf2•) formed by the oxidation of NTf2- at anodic potential can catalyze the oxidation of hydrogen and enhance its reaction rate. Both experimental and theoretical studies (DFT) have supported a mechanism involving a NTf2• radical intermediate that catalyzes the hydrogen redox processes.
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Affiliation(s)
- Yongan Tang
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Lu Lin
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Anil Kumar
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Min Guo
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Michael Sevilla
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
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19
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Tang Y, Zeng X. Electrochemical Oxidation of Hydrogen in Bis(trifluoromethylsulfonyl)imide Ionic Liquids under Anaerobic and Aerobic Conditions. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:23542-23551. [PMID: 29043009 PMCID: PMC5641470 DOI: 10.1021/acs.jpcc.6b07067] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The electrochemical behavior of hydrogen oxidation on a platinum electrode in two aprotic room temperature ionic liquids (RTILs)-1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Bmim][NTf2] and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [Bmpy][NTf2]-was investigated in both anaerobic and aerobic conditions. At platinum electrode in the ILs, the first step of hydrogen oxidation is the formation of Pt-H(ad) (the Tafel step), which is similar to those observed in the aqueous electrolytes. However, there are differences in the oxidation steps (the Heyrovsky and Volmer steps). In ILs, the oxidation of Pt-H(ad) forms a hydrogen radical and a proton rather than a proton or a water in aqueous acid or alkaline electrolytes, respectively. This difference is significant as it results in a completely different following reaction pathway in the anaerobic vs aerobic conditions. A coupled chemical reaction between oxygen and hydrogen oxidation intermediates was observed in aerobic conditions which has a correlation with hydrogen concentrations. Furthermore, the overall rate of hydrogen oxidation is shown to be much higher in [Bmpy][NTf2] than that of [Bmim][NTf2], which is rationalized as the result of both higher solubility of hydrogen and the unique IL-electrode interface structure which promotes the hydrogen adsorption in [Bmpy][NTf2] than that of [Bmim][NTf2]. This study is the first example showing that hydrogen oxidation mechanism in aprotic ILs follows two different oxidation mechanisms in anaerobic and aerobic conditions.
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Liu Z, Huang Z, Cheng F, Guo Z, Wang G, Chen X, Wang Z. Efficient Dual-Site Carbon Monoxide Electro-Catalysts via Interfacial Nano-Engineering. Sci Rep 2016; 6:33127. [PMID: 27650532 PMCID: PMC5030650 DOI: 10.1038/srep33127] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/19/2016] [Indexed: 11/09/2022] Open
Abstract
Durable, highly efficient, and economic sound electrocatalysts for CO electrooxidation (COE) are the emerging key for wide variety of energy solutions, especially fuel cells and rechargeable metal-air batteries. Herein, we report the novel system of nickel-aluminum double layered hydroxide (NiAl-LDH) nanoplates on carbon nanotubes (CNTs) network. The formulation of such complexes system was to be induced through the assistance of gold nanoparticles in order to form dual-metal active sites so as to create a extended Au/NiO two phase zone. Bis (trifluoromethylsulfonyl)imide (NTf2) anion of ionic liquid electrolyte was selected to enhance the CO/O2 adsorption and to facilitate electro-catalyzed oxidation of Ni (OH)2 to NiOOH by increasing the electrophilicity of catalytic interface. The resulting neutral catalytic system exhibited ultra-high electrocatalytic activity and stability for CO electrooxidation than commercial and other reported precious metal catalysts. The turnover frequency (TOF) of the LDH-Au/CNTs COE catalyst was much higher than the previous reported other similar electrocatalysts, even close to the activity of solid-gas chemical catalysts at high temperature. Moreover, in the long-term durability testing, the negligible variation of current density remains exsisting after 1000 electrochemistry cycles.
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Affiliation(s)
- Zhen Liu
- Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, USA
- Department of Physics & Engineering, Frostburg State University, Frostburg, MD 21532-2303, USA
- Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
| | - Zhongyuan Huang
- Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, USA
| | - Feifei Cheng
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhanhu Guo
- Integrated Composites Laboratory (ICL), Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Guangdi Wang
- Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, USA
| | - Xu Chen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhe Wang
- Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 70125, USA
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21
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Chi X, Tang Y, Zeng X. Electrode Reactions Coupled with Chemical Reactions of Oxygen, Water and Acetaldehyde in an Ionic Liquid: New Approaches for Sensing Volatile Organic Compounds. Electrochim Acta 2016; 216:171-180. [PMID: 29142331 DOI: 10.1016/j.electacta.2016.08.108] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Water and oxygen are ubiquitous present in ambient conditions. This work studies the unique oxygen, trace water and a volatile organic compound (VOC) acetaldehyde redox chemistry in a hydrophobic and aprotic ionic liquid (IL), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([Bmpy] [NTf2]) by cyclic voltammetry and potential step methods. One electron oxygen reduction leads to superoxide radical formation in the IL. Trace water in the IL acts as a protic species that reacts with the superoxide radical. Acetaldehyde is a stronger protic species than water for reacting with the superoxide radical. The presence of trace water in the IL was also demonstrated to facilitate the electro-oxidation of acetaldehyde, with similar mechanism to that in the aqueous solutions. A multiple-step coupling reaction mechanism between water, superoxide radical and acetaldehyde has been described. The unique characteristics of redox chemistry of acetaldehyde in [Bmpy][NTf2] in the presence of oxygen and trace water can be controlled by electrochemical potentials. By controlling the electrode potential windows, several methods including cyclic voltammetry, potential step methods (single-potential, double-potential and triple-potential step methods) were established for the quantification of acetaldehyde. Instead of treating water and oxygen as frustrating interferents to ILs, we found that oxygen and trace water chemistry in [Bmpy][NTf2] can be utilized to develop innovative electrochemical methods for electroanalysis of acetaldehyde.
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Affiliation(s)
- Xiaowei Chi
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Yongan Tang
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, United States
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Li H, Boling S, Mason AJ. CMOS Amperometric ADC With High Sensitivity, Dynamic Range and Power Efficiency for Air Quality Monitoring. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2016; 10:817-27. [PMID: 27352395 PMCID: PMC5056750 DOI: 10.1109/tbcas.2016.2571306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Airborne pollutants are a leading cause of illness and mortality globally. Electrochemical gas sensors show great promise for personal air quality monitoring to address this worldwide health crisis. However, implementing miniaturized arrays of such sensors demands high performance instrumentation circuits that simultaneously meet challenging power, area, sensitivity, noise and dynamic range goals. This paper presents a new multi-channel CMOS amperometric ADC featuring pixel-level architecture for gas sensor arrays. The circuit combines digital modulation of input currents and an incremental Σ∆ ADC to achieve wide dynamic range and high sensitivity with very high power efficiency and compact size. Fabricated in 0.5 [Formula: see text] CMOS, the circuit was measured to have 164 dB cross-scale dynamic range, 100 fA sensitivity while consuming only 241 [Formula: see text] and 0.157 [Formula: see text] active area per channel. Electrochemical experiments with liquid and gas targets demonstrate the circuit's real-time response to a wide range of analyte concentrations.
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23
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Tang Y, Chi X, Zou S, Zeng X. Facet effects of palladium nanocrystals for oxygen reduction in ionic liquids and for sensing applications. NANOSCALE 2016; 8:5771-9. [PMID: 26910528 PMCID: PMC5640266 DOI: 10.1039/c5nr07502e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Palladium nanocrystals enclosed by {100} and {110} crystal facets, were successfully synthesized through an aqueous one-pot synthesis method. A new thermal annealing approach was developed for fabricating these palladium nanocrystals as a working electrode on a gas permeable membrane to study the facet effects of the oxygen reduction process in an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf2]). Results were compared with the same processes at a conventional platinum electrode. Our study shows that the structural difference between the two facets of Pd nanocrystals has little effect on the oxygen reduction process but significantly affects the oxidation process of the superoxide. It is found that the Pd{110}/IL interface can better stabilize superoxide radicals revealed by a more positive oxidation potential compared to that of Pd{100}. In addition, the analytical characteristic of utilizing both palladium nanocrystals as electrodes for oxygen sensing is comparable with a polycrystal platinum oxygen sensor, in which Pd{110} presents the best sensitivity and lowest detection limit. Our results demonstrate the facet-dependence of oxygen reduction in an ionic liquid medium and provide the fundamental information needed to guide the applications of palladium nanocrystals in electrochemical gas sensor and fuel cell research.
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Affiliation(s)
- Yongan Tang
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
| | - Xiaowei Chi
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
| | - Shouzhong Zou
- Department of Chemistry, American University, Washington DC 20016, USA
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
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Lin L, Rehman A, Chi X, Zeng X. 2,4-Toluene diisocyanate detection in liquid and gas environments through electrochemical oxidation in an ionic liquid. Analyst 2016; 141:1519-29. [PMID: 26763507 PMCID: PMC4756716 DOI: 10.1039/c5an02220g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electrochemical oxidation of 2,4-toluene diisocyanate (2,4-TDI) in an ionic liquid (IL) has been systematically characterized to determine plausible electrochemical and chemical reaction mechanisms and to define the optimal detection methods for such a highly significant analyte. It has been found that the use of an IL as the electrolyte allows the oxidation of 2,4-TDI to occur at a less positive anodic potential with no side reactions as compared to traditional acetonitrile based electrolytes. UV-Vis, FT-IR, cyclic voltammetry and Electrochemical Impedance Spectroscopy (EIS) studies have revealed the unique mechanisms of dimerization of 2,4-TDI at the electrode interface by self-addition reactions, which can be utilized to improve the selectivity of detection. The study of 2,4-TDI redox chemistry further facilitates the development of a robust amperometric sensing methodology by selecting a hydrophobic IL ([C4mpy][NTf2]) and by restricting the potential window to only include the oxidation process. Thus, this innovative electrochemical sensor is capable of avoiding the two most ubiquitous interferents in ambient conditions (i.e. humidity and oxygen), thereby enhancing the sensor performance and reliability for real world applications. The method was established to detect 2,4-TDI in both liquid and gas phases. The limits of detection (LOD) values were 130.2 ppm and 0.7862 ppm, respectively, for the two phases, and are comparable to the safety standards reported by NIOSH. The as-developed 2.4-TDI amperometric sensor exhibits a sensitivity of 1.939 μA ppm(-1). Moreover, due to the simplicity of design and the use of an IL both as a solvent and non-volatile electrolyte, the sensor has the potential to be miniaturized for smart sensing protocols in distributed sensor applications.
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Affiliation(s)
- Lu Lin
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
| | - Abdul Rehman
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
| | - Xiaowei Chi
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
| | - Xiangqun Zeng
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.
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Tang Y, Wang Z, Chi X, Sevilla MD, Zeng X. In Situ Generated Platinum Catalyst for Methanol Oxidation via Electrochemical Oxidation of Bis(trifluoromethylsulfonyl)imide Anion in Ionic Liquids at Anaerobic Condition. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:1004-1012. [PMID: 29034058 PMCID: PMC5640268 DOI: 10.1021/acs.jpcc.5b09777] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The bis(trifluoromethylsulfonyl)imide anion is widely used as an ionic liquid anion due to its electrochemical stability and wide electrochemical potential window at aerobic conditions. Here we report an innovative strategy by directly oxidizing bis(trifluoromethylsulfonyl)imide anion to form a radical electrocatalyst on platinum electrode at anaerobic condition. The in situ generated radical catalyst was shown to catalytically and selectively promote the electrooxidation of methanol to form methoxyl radical, in which the formation potential was drastically decreased with the existence of bis(trifluoromethylsulfonyl)imide radical. The electrochemically generated radical catalyst not only facilitates the oxidation of methanol but also provides good selectivity. The unique double layer structure of the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf2]) likely excludes the diffusion of larger molar mass molecules onto the electrode surface and enables the highly selective methanol oxidation at this IL-electrode interface. Cyclic voltammetry (CV) experiments were used to systematically characterize the details of the electrochemical processes with and without methanol in several other ILs, and a mechanism of the chemical and redox processes was proposed. This study provides a promising new approach for utilizing the unique properties of ionic liquids not only as solvents and electrolytes but also as the medium for in situ generation of electrocatalysts to promote methanol redox reactions for practical applications.
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Fedorenko GV, Oleksenko LP, Maksymovych NP, Matushko IP. Semiconductor adsorption sensors based on nanosized Pt/SnO2 materials and their sensitivity to methane. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2015. [DOI: 10.1134/s0036024415120110] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Rehman A, Zeng X. Methods and approaches of utilizing ionic liquids as gas sensing materials. RSC Adv 2015; 5:58371-58392. [PMID: 29142738 PMCID: PMC5683717 DOI: 10.1039/c5ra06754e] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Gas monitoring is of increasing significance for a broad range of applications in the fields of environmental and civil infrastructures, climate and energy, health and safety, industry and commerce. Even though there are many gas detection devices and systems available, the increasing needs for better detection technologies that not only satisfy the high analytical standards but also meet additional device requirements (e.g., being robust to survive under field conditions, low cost, small, smart, more mobile), demand continuous efforts in developing new methods and approaches for gas detection. Ionic Liquids (ILs) have attracted a tremendous interest as potential sensing materials for the gas sensor development. Being composed entirely of ions and with a broad structural and functional diversity, i.e., bifunctional (organic/inorganic), biphasic (solid/liquid) and dual-property (solvent/electrolyte), they have the complementing attributes and the required variability to allow a systematic design process across many sensing components to enhance sensing capability especially for miniaturized sensor system implementation. The emphasis of this review is to describe molecular design and control of IL interface materials to provide selective and reproducible response and to synergistically integrate IL sensing materials with low cost and low power electrochemical, piezoelectric/QCM and optical transducers to address many gas detection challenges (e.g., sensitivity, selectivity, reproducibility, speed, stability, cost, sensor miniaturization, and robustness). We further show examples to justify the importance of understanding the mechanisms and principles of physicochemical and electrochemical reactions in ILs and then link those concepts to developing new sensing methods and approaches. By doing this, we hope to stimulate further research towards the fundamental understanding of the sensing mechanisms and new sensor system development and integration, using simple sensing designs and flexible sensor structures both in terms of scientific operation and user interface that can be miniaturized and interfaced with modern wireless monitoring technologies to achieve specifications heretofore unavailable on current markets for the next generation of gas sensor applications.
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