2D Materials for Gas Sensing

A special issue of Chemosensors (ISSN 2227-9040). This special issue belongs to the section "Materials for Chemical Sensing".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 35542

Special Issue Editors


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Guest Editor
School of physics and materials science, Guangzhou University, Guangzhou, China
Interests: gas sensors; sensor array; 2D materials; graphene; Van der Waals materials; 2D hybrid materials; printed electronics; flexible sensors

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Guest Editor
Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK
Interests: nanomaterials; composite materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Since the first discovery of graphene, two dimensional (2D)-structured nanomaterials have attracted extensive research interest worldwide. Benefitting from their tremendous surface–volume ratio, atomical thickness, as well as excellent conducting or semiconducting property, 2D-structured materials have also exhibited extraordinary potential in the gas detection field. Specifically, their unique 2D structure exposes most of their atoms, which could then interact with environmental gas molecules and output enormous signals. Moreover, the capability of 2D nanomaterials to identify gas analytes at room temperature, as well as their inherent flexible property, render them to be a promising candidate for constructing flexible and wearable gas sensors integrated on a low Young's modulus substrate. Even so, numerous challenges, including selectivity, sensitivity, response time, recovery time, and stability, must be addressed before the practical application of 2D nanomaterials in the gas detection field.

This Special Issue aims to collect the latest research works in the field of 2D materials-based gas sensors, including new 2D materials and new 2D-based composite materials for the use of industrial, agricultural, environmental, medical and domestic gas detection. The Special Issue will also focus on the new sensing mechanism, new sensor design, and new fabrication method of 2D materials-based gas sensors to address the abovementioned challenges. The Special Issue welcomes original research articles, reviews, communications and concept papers.

Potential topics include, but are not limited to, the following:

  • New 2D materials for gas detection;
  • New fabrication method for 2D materials-based gas sensors;
  • New 2D materials-based composites for gas detection;
  • First-principle calculation for gas sensing mechanism of 2D materials;
  • 2D materials-based flexible or wearable gas sensors;
  • 2D materials-based gas sensors for industrial safety;
  • 2D materials-based gas sensors for medical diagnosis;
  • 2D materials-based gas sensors for human health;
  • 2D materials-based printed gas sensors;
  • 2D materials-based gas sensor array;

Dr. Shaolin Zhang
Dr. Fang Xu
Guest Editors

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Published Papers (10 papers)

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Research

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15 pages, 1083 KiB  
Article
Noise Spectrum as a Source of Information in Gas Sensors Based on Liquid-Phase Exfoliated Graphene
by Stevan Andrić, Ivana Jokić, Jelena Stevanović, Marko Spasenović and Miloš Frantlović
Chemosensors 2022, 10(6), 224; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors10060224 - 14 Jun 2022
Cited by 1 | Viewed by 1632
Abstract
Surfaces of adsorption-based gas sensors are often heterogeneous, with adsorption sites that differ in their affinities for gas particle binding. Knowing adsorption/desorption energies, surface densities and the relative abundance of sites of different types is important, because these parameters impact sensor sensitivity and [...] Read more.
Surfaces of adsorption-based gas sensors are often heterogeneous, with adsorption sites that differ in their affinities for gas particle binding. Knowing adsorption/desorption energies, surface densities and the relative abundance of sites of different types is important, because these parameters impact sensor sensitivity and selectivity, and are relevant for revealing the response-generating mechanisms. We show that the analysis of the noise of adsorption-based sensors can be used to study gas adsorption on heterogeneous sensing surfaces, which is applicable to industrially important liquid-phase exfoliated (LPE) graphene. Our results for CO2 adsorption on an LPE graphene surface, with different types of adsorption sites on graphene flake edges and basal planes, show that the noise spectrum data can be used to characterize such surfaces in terms of parameters that determine the sensing properties of the adsorbing material. Notably, the spectrum characteristic frequencies are an unambiguous indicator of the relative abundance of different types of adsorption sites on the sensing surface and their surface densities. We also demonstrate that spectrum features indicate the fraction of the binding sites that are already occupied by another gas species. The presented study can be applied to the design and production of graphene and other sensing surfaces with an optimal sensing performance. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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15 pages, 6602 KiB  
Communication
The SnO2/MXene Composite Ethanol Sensor Based on MEMS Platform
by Chen Wang, Runlong Li, Lingyan Feng and Jiaqiang Xu
Chemosensors 2022, 10(3), 109; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors10030109 - 11 Mar 2022
Cited by 19 | Viewed by 3626
Abstract
In recent years, two-dimensional layered material MXene has attracted extensive attention in the fields of sensors due to its large specific surface area and rich active sites. So, we employed multilayer Ti3C2TX and SnO2 microspheres to prepare [...] Read more.
In recent years, two-dimensional layered material MXene has attracted extensive attention in the fields of sensors due to its large specific surface area and rich active sites. So, we employed multilayer Ti3C2TX and SnO2 microspheres to prepare SnO2/MXene composites for enhancing gas-sensing properties of pristine SnO2. The composite was brushed on a microelectromechanical system (MEMS) platform to make resistance-type gas sensors with low power consumption. The gas-sensing results show that the SnO2/MXene sensor with the best composite ratio (SnO2: MXene mass ratio is 5:1, named SM-5) greatly improves gas sensitivity of SnO2 sensor, among which the sensitivity to ethanol gas is the highest. At the same time, the composite also speeds up the response recovery speed of the sensor. When the SM-5 sensor worked at its optimal temperature 230 °C, its response value to 10 ppm ethanol reaches 5.0, which is twice that of the pristine SnO2 sensor. Its response and recovery time are only 14 s and 26 s, respectively. The sensing mechanism of the composite is discussed according to the classical the space charge or depletion layer model. It is concluded that the Schottky barrier of composites and the metal properties of Ti3C2Tx are responsible for improvement of the gas-sensing properties of the composite. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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16 pages, 4429 KiB  
Article
Flexible Low-Temperature Ammonia Gas Sensor Based on Reduced Graphene Oxide and Molybdenum Disulfide
by Zhe Ren, Yunbo Shi, Tianming Song, Tian Wang, Bolun Tang, Haodong Niu and Xiaoyu Yu
Chemosensors 2021, 9(12), 345; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9120345 - 07 Dec 2021
Cited by 9 | Viewed by 3046
Abstract
Owing to harsh working environments and complex industrial requirements, traditional gas sensors are prone to deformation damage, possess a limited detection range, require a high working temperature, and display low reliability, thereby necessitating the development of flexible and low-temperature gas sensors. In this [...] Read more.
Owing to harsh working environments and complex industrial requirements, traditional gas sensors are prone to deformation damage, possess a limited detection range, require a high working temperature, and display low reliability, thereby necessitating the development of flexible and low-temperature gas sensors. In this study, we developed a low-temperature polyimide (PI)-based flexible gas sensor comprising a reduced graphene oxide (rGO)/MoS2 composite. The micro-electro-mechanical system technology was used to fabricate Au electrodes on a flexible PI sheet to form a “sandwiched” sensor structure. The rGO/MoS2 composites were synthesized via a one-step hydrothermal method. The gas-sensing response was the highest for the composite comprising 10% rGO. The structure of this material was characterized, and a PI-based flexible gas sensor comprising rGO/MoS2 was fabricated. The optimal working temperature of the sensor was 141 °C, and its response-recovery time was significantly short upon exposure to 50–1500 ppm NH3. Thus, this sensor exhibited high selectivity and a wide NH3 detection range. Furthermore, it possessed the advantages of low power consumption, a short response-recovery time, a low working temperature, flexibility, and variability. Our findings provide a new framework for the development of pollutant sensors that can be utilized in an industrial environment. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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11 pages, 3032 KiB  
Article
Carbon Dioxide Sensing with Langmuir–Blodgett Graphene Films
by Stevan Andrić, Milija Sarajlić, Miloš Frantlović, Ivana Jokić, Dana Vasiljević-Radović and Marko Spasenović
Chemosensors 2021, 9(12), 342; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9120342 - 03 Dec 2021
Cited by 7 | Viewed by 3069
Abstract
Graphene has become a material of choice for an increasing number of scientific and industrial applications. It has been used for gas sensing due to its favorable properties, such as a large specific surface area, as well as the sensitivity of its electrical [...] Read more.
Graphene has become a material of choice for an increasing number of scientific and industrial applications. It has been used for gas sensing due to its favorable properties, such as a large specific surface area, as well as the sensitivity of its electrical parameters to adsorption processes occurring on its surface. Efforts are ongoing to produce graphene gas sensors by using methods that are compatible with scaling, simple deposition techniques on arbitrary substrates, and ease of use. In this paper, we demonstrate the fabrication of carbon dioxide gas sensors from Langmuir–Blodgett thin films of sulfonated polyaniline-functionalized graphene that was obtained by using electrochemical exfoliation. The sensor was tested within the highly relevant concentration range of 150 to 10,000 ppm and 0% to 100% at room temperature (15 to 35 °C). The results show that the sensor has both high sensitivity to low analyte concentrations and high dynamic range. The sensor response times are approximately 15 s. The fabrication method is simple, scalable, and compatible with arbitrary substrates, which makes it potentially interesting for many practical applications. The sensor is used for real-time carbon dioxide concentration monitoring based on a theoretical model matched to our experimental data. The sensor performance was unchanged over a period of several months. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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12 pages, 6154 KiB  
Article
Ppb-Level Butanone Sensor Based on ZnO-TiO2-rGO Nanocomposites
by Zhijia Liao, Yao Yu, Zhenyu Yuan and Fanli Meng
Chemosensors 2021, 9(10), 284; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9100284 - 06 Oct 2021
Cited by 6 | Viewed by 1997
Abstract
In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, [...] Read more.
In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, triggering skin irritation in mild cases and affecting our breathing in severe cases. In this paper, the gas-sensing properties of TiO2, ZnO, ZnO-TiO2, and ZnO-TiO2-rGO nanomaterials to butanone vapor were studied. The optimum operating temperature of the ZnO-TiO2-rGO sensor is 145 °C, which is substantially lower than the other three sensors. The selectivity for butanone vapor is greatly improved, and the response is 5.6 times higher than that of other organic gases. The lower detection limit to butanone can reach 63 ppb. Therefore, the ZnO-TiO2-rGO sensor demonstrates excellent gas-sensing performance to butanone. Meanwhile, the gas-sensing mechanism of the ZnO-TiO2-rGO sensor to butanone vapor was also analyzed. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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14 pages, 2312 KiB  
Article
Chemical Sensing Properties of BaF2-Modified hBN Flakes towards Detection of Volatile Organic Compounds
by Boitumelo J. Matsoso, Clara Garcia-Martinez, Thomas H. Mongwe, Bérangère Toury, José P. M. Serbena and Catherine Journet
Chemosensors 2021, 9(9), 263; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9090263 - 13 Sep 2021
Viewed by 2315
Abstract
The application of BaF2-modified hBN flakes as rapid response and recovery as well as sensitive chemoresistive sensing device materials for detection of acetone and/or ethanol is presented in this study. Modification of the hBN flakes was achieved by using [...] Read more.
The application of BaF2-modified hBN flakes as rapid response and recovery as well as sensitive chemoresistive sensing device materials for detection of acetone and/or ethanol is presented in this study. Modification of the hBN flakes was achieved by using the modified polymer derived ceramics (PDCs) process through the use of 0–10 wt% BaF2 and 5 wt% Li3N. Upon exposure to individual acetone and ethanol vapours, room temperature sensing studies revealed high LoD values (−144–460 ppmacetone and −134–543 ppmethanol) with extremely compromised sensitivities of −0.042–0.72 × 10−2 ppm−1acetone and −0.045–0.19 × 10−2 ppm−1ethanol for the structurally improved 5–10 wt% BaF2-modified hBN flakes. Moreover, enhanced sensing for 0–2.5 wt% BaF2-modified hBN flakes, as shown by the low LoDs (−43–86 ppmacetone and −30–62 ppmethanol) and the high sensitivities (−1.8–2.1 × 10−2 ppm−1acetone and −1.5–1.6 × 10−2 ppm−1ethanol), was attributed to the presence of defects subsequently providing an abundance of adsorption sites. Overall, the study demonstrated the importance of structural properties of hBN flakes on their surface chemistry towards room temperature selective and sensitive detection of VOCs. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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11 pages, 2134 KiB  
Communication
Nitrogen Dioxide Gas Sensor Based on Ag-Doped Graphene: A First-Principle Study
by Qichao Li, Yamin Liu, Di Chen, Jianmin Miao, Xiao Zhi, Shengwei Deng, Shujing Lin, Han Jin and Daxiang Cui
Chemosensors 2021, 9(8), 227; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9080227 - 14 Aug 2021
Cited by 15 | Viewed by 3211
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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14 pages, 4148 KiB  
Article
Ultrathin Leaf-Shaped CuO Nanosheets Based Sensor Device for Enhanced Hydrogen Sulfide Gas Sensing Application
by Ahmad Umar, Hassan Algadi, Rajesh Kumar, Mohammad Shaheer Akhtar, Ahmed A. Ibrahim, Hasan Albargi, Mohsen A. M. Alhamami, Turki Alsuwian and Wen Zeng
Chemosensors 2021, 9(8), 221; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9080221 - 11 Aug 2021
Cited by 7 | Viewed by 2429
Abstract
Herein, a simple, economical and low temperature synthesis of leaf-shaped CuO nanosheets is reported. As-synthesized CuO was examined through different techniques including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), fourier [...] Read more.
Herein, a simple, economical and low temperature synthesis of leaf-shaped CuO nanosheets is reported. As-synthesized CuO was examined through different techniques including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), fourier transform infrared spectroscopic (FTIR) and Raman spectroscopy to ascertain the purity, crystal phase, morphology, vibrational, optical and diffraction features. FESEM and TEM images revealed a thin leaf-like morphology for CuO nanosheets. An interplanar distance of ~0.25 nm corresponding to the (110) diffraction plane of the monoclinic phase of the CuO was revealed from the HRTEM images XRD analysis indicated a monoclinic tenorite crystalline phase of the synthesized CuO nanosheets. The average crystallite size for leaf-shaped CuO nanosheets was found to be 14.28 nm. Furthermore, a chemo-resistive-type gas sensor based on leaf-shaped CuO nanosheets was fabricated to effectively and selectively detect H2S gas. The fabricated sensor showed maximum gas response at an optimized temperature of 300 °C towards 200 ppm H2S gas. The corresponding response and recovery times were 97 s and 100 s, respectively. The leaf-shaped CuO nanosheets-based gas sensor also exhibited excellent selectivity towards H2S gas as compared to other analyte gases including NH3, CH3OH, CH3CH2OH, CO and H2. Finally, we have proposed a gas sensing mechanism based upon the formation of chemo-resistive CuO nanosheets. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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15 pages, 2821 KiB  
Article
Theoretical and Experimental Research on Ammonia Sensing Properties of Sulfur-Doped Graphene Oxide
by Yao Yu, Zhijia Liao, Fanli Meng and Zhenyu Yuan
Chemosensors 2021, 9(8), 220; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9080220 - 11 Aug 2021
Cited by 8 | Viewed by 2158
Abstract
In this paper, gas sensing characteristics of sulfur-doped graphene oxide (S-GO) are firstly presented. The results of the sensing test revealed that, at room temperature (20 °C), S-GO has the optimal sensitivity to NH3. The S-GO gas sensor has a relatively [...] Read more.
In this paper, gas sensing characteristics of sulfur-doped graphene oxide (S-GO) are firstly presented. The results of the sensing test revealed that, at room temperature (20 °C), S-GO has the optimal sensitivity to NH3. The S-GO gas sensor has a relatively short response and recovery time for the NH3 detection. Further, the sensing limit of ammonia at room temperature is 0.5 ppm. Theoretical models of graphene and S-doped graphene are established, and electrical properties of the graphene and S-doped graphene are calculated. The enhanced sensing performance was ascribed to the electrical properties’ improvement after the graphene was S-doped. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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Review

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42 pages, 16060 KiB  
Review
Preparation and Application of 2D MXene-Based Gas Sensors: A Review
by Qingting Li, Yanqiong Li and Wen Zeng
Chemosensors 2021, 9(8), 225; https://0-doi-org.brum.beds.ac.uk/10.3390/chemosensors9080225 - 14 Aug 2021
Cited by 71 | Viewed by 10662
Abstract
Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of [...] Read more.
Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed. Full article
(This article belongs to the Special Issue 2D Materials for Gas Sensing)
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