Special Issue "Development of Semiconductor Nanomaterials for Gas Sensors"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (1 October 2018)

Special Issue Editors

Guest Editor
Prof. Dr. Alexander M. Gaskov

Chemistry Department, Moscow State University, Leninskie Gory 1-3, 119991 Moscow, Russia
Website | E-Mail
Phone: +7(495)939-54-71
Interests: inorganic chemistry, advanced materials, semiconductors, surface characterization, thin films, nanocrystalline metal oxides, quantum dots
Guest Editor
Prof. Dr. Marina N. Rumyantseva

Chemistry Department, Moscow State University, Leninskie Gory 1-3, 119991 Moscow, Russia
Website | E-Mail
Phone: +7(495)939-54-71
Interests: metal oxides; semiconductors; nanomaterials; chemical sensors; nanocomposites; hybrid materials; surface chemistry

Special Issue Information

Dear Colleagues,

Despite the long history of research, materials for semiconductor gas sensors are still being actively studied. To respond to the constantly-emerging new challenges for sensor devices, it is necessary to improve the known, and search for new, materials that have improved sensor characteristics: Sensitivity, selectivity and stability in humid conditions in combination with short response and recovery time, and low power consumption. For a conscious modification of known materials and a directional choice of new materials for gas sensors, fundamental research is needed to ensure the knowledge of the mechanisms of the processes responsible for the sensor signal formation, as well as the understanding of the relationships between the functional properties of materials, the characteristics of the active centers on their surfaces, and the parameters of their microstructure. In turn, these characteristics are determined by the synthesis conditions.

Thus, you are invited to submit contributions that are devoted to the synthesis of nanocrystalline semiconductor materials from the gas and liquid phases, and to the analysis of the interconnections "composition–structure–properties" for materials of different dimensionality (3D, 2D, 1D), and of various chemical nature. Characterization of the surface composition in terms of hydrophobic / hydrophilic properties is of considerable interest. Taking into account the high activity of nanocrystalline systems in the interaction with the gas phase, the in situ and operando studies of the mechanism of sensor signal formation are particularly welcome.

Prof. Dr. Alexander M. Gaskov
Prof. Dr. Marina N. Rumyantseva
Guest Editors

Manuscript Submission Information

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Keywords

  • metal oxide semiconductors
  • non-oxide semiconductors
  • 1D- and 2D-semiconductor materials
  • active surface centers
  • solid-gas interaction
  • in situ and operando investigations

Published Papers (9 papers)

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Research

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Open AccessArticle Pd-Functionalized SnO2 Nanofibers Prepared by Shaddock Peels as Bio-Templates for High Gas Sensing Performance toward Butane
Nanomaterials 2019, 9(1), 13; https://doi.org/10.3390/nano9010013
Received: 8 November 2018 / Revised: 16 December 2018 / Accepted: 20 December 2018 / Published: 23 December 2018
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Abstract
Pd-functionalized one-dimensional (1D) SnO2 nanostructures were synthesized via a facile hydrothermal method and shaddock peels were used as bio-templates to induce a 1D-fiber-like morphology into the gas sensing materials. The gas-sensing performances of sensors based on different ratios of Pd-functionalized SnO2 [...] Read more.
Pd-functionalized one-dimensional (1D) SnO2 nanostructures were synthesized via a facile hydrothermal method and shaddock peels were used as bio-templates to induce a 1D-fiber-like morphology into the gas sensing materials. The gas-sensing performances of sensors based on different ratios of Pd-functionalized SnO2 composites were measured. All results indicate that the sensor based on 5 mol % Pd-functionalized SnO2 composites exhibited significantly enhanced gas-sensing performances toward butane. With regard to pure SnO2, enhanced levels of gas response and selectivity were observed. With 5 mol % Pd-functionalized SnO2 composites, detection limits as low as 10 ppm with responses of 1.38 ± 0.26 were attained. Additionally, the sensor exhibited rapid response/recovery times (3.20/6.28 s) at 3000 ppm butane, good repeatability and long-term stability, demonstrating their potential in practical applications. The excellent gas-sensing performances are attributed to the unique one-dimensional morphology and the large internal surface area of sensing materials afforded using bio-templates, which provide more active sites for the reaction between butane molecules and adsorbed oxygen ions. The catalysis and “spillover effect” of Pd nanoparticles also play an important role in the sensing of butane gas as further discussed in the paper. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Influence of Mono- and Bimetallic PtOx, PdOx, PtPdOx Clusters on CO Sensing by SnO2 Based Gas Sensors
Nanomaterials 2018, 8(11), 917; https://doi.org/10.3390/nano8110917
Received: 17 October 2018 / Revised: 31 October 2018 / Accepted: 3 November 2018 / Published: 7 November 2018
Cited by 3 | PDF Full-text (5559 KB) | HTML Full-text | XML Full-text
Abstract
To obtain a nanocrystalline SnO2 matrix and mono- and bimetallic nanocomposites SnO2/Pd, SnO2/Pt, and SnO2/PtPd, a flame spray pyrolysis with subsequent impregnation was used. The materials were characterized using X-ray diffraction (XRD), a single-point BET method, [...] Read more.
To obtain a nanocrystalline SnO2 matrix and mono- and bimetallic nanocomposites SnO2/Pd, SnO2/Pt, and SnO2/PtPd, a flame spray pyrolysis with subsequent impregnation was used. The materials were characterized using X-ray diffraction (XRD), a single-point BET method, transmission electron microscopy (TEM), and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy dispersive X-ray (EDX) mapping. The electronic state of the metals in mono- and bimetallic clusters was determined using X-ray photoelectron spectroscopy (XPS). The active surface sites were investigated using the Fourier Transform infrared spectroscopy (FTIR) and thermo-programmed reduction with hydrogen (TPR-H2) methods. The sensor response of blank SnO2 and nanocomposites had a carbon monoxide (CO) level of 6.7 ppm and was determined in the temperature range 60–300 °C in dry (Relative Humidity (RH) = 0%) and humid (RH = 20%) air. The sensor properties of the mono- and bimetallic nanocomposites were analyzed on the basis of information on the electronic state, the distribution of modifiers in SnO2 matrix, and active surface centers. For SnO2/PtPd, the combined effect of the modifiers on the electrophysical properties of SnO2 explained the inversion of sensor response from n- to p-types observed in dry conditions. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Significant Enhancement of Hydrogen-Sensing Properties of ZnO Nanofibers through NiO Loading
Nanomaterials 2018, 8(11), 902; https://doi.org/10.3390/nano8110902
Received: 18 October 2018 / Revised: 1 November 2018 / Accepted: 2 November 2018 / Published: 3 November 2018
Cited by 4 | PDF Full-text (4370 KB) | HTML Full-text | XML Full-text
Abstract
Metal oxide p-n heterojunction nanofibers (NFs) are among the most promising approaches to enhancing the efficiency of gas sensors. In this paper, we report the preparation of a series of p-NiO-loaded n-ZnO NFs, namely (1−x)ZnO-xNiO (x = 0.03, 0.05, [...] Read more.
Metal oxide p-n heterojunction nanofibers (NFs) are among the most promising approaches to enhancing the efficiency of gas sensors. In this paper, we report the preparation of a series of p-NiO-loaded n-ZnO NFs, namely (1−x)ZnO-xNiO (x = 0.03, 0.05, 0.7, 0.1, and 0.15 wt%), for hydrogen gas sensing experiments. Samples were prepared through the electrospinning technique followed by a calcination process. The sensing experiments showed that the sample with 0.05 wt% NiO loading resulted in the highest sensing performance at an optimal sensing temperature of 200 °C. The sensing mechanism is discussed in detail and contributions of the p-n heterojunctions, metallization of ZnO and catalytic effect of NiO on the sensing enhancements of an optimized gas sensor are analyzed. This study demonstrates the possibility of fabricating high-performance H2 sensors through the optimization of p-type metal oxide loading on the surfaces of n-type metal oxides. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Rhodium Oxide Surface-Loaded Gas Sensors
Nanomaterials 2018, 8(11), 892; https://doi.org/10.3390/nano8110892
Received: 4 October 2018 / Revised: 24 October 2018 / Accepted: 25 October 2018 / Published: 1 November 2018
Cited by 2 | PDF Full-text (4399 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In order to increase their stability and tune-sensing characteristics, metal oxides are often surface-loaded with noble metals. Although a great deal of empirical work shows that surface-loading with noble metals drastically changes sensing characteristics, little information exists on the mechanism. Here, a systematic [...] Read more.
In order to increase their stability and tune-sensing characteristics, metal oxides are often surface-loaded with noble metals. Although a great deal of empirical work shows that surface-loading with noble metals drastically changes sensing characteristics, little information exists on the mechanism. Here, a systematic study of sensors based on rhodium-loaded WO3, SnO2, and In2O3—examined using X-ray diffraction, high-resolution scanning transmission electron microscopy, direct current (DC) resistance measurements, operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and operando X-ray absorption spectroscopy—is presented. Under normal sensing conditions, the rhodium clusters were oxidized. Significant evidence is provided that, in this case, the sensing is dominated by a Fermi-level pinning mechanism, i.e., the reaction with the target gas takes place on the noble-metal cluster, changing its oxidation state. As a result, the heterojunction between the oxidized rhodium clusters and the base metal oxide was altered and a change in the resistance was detected. Through measurements done in low-oxygen background, it was possible to induce a mechanism switch by reducing the clusters to their metallic state. At this point, there was a significant drop in the overall resistance, and the reaction between the target gas and the base material was again visible. For decades, noble metal loading was used to change the characteristics of metal-oxide-based sensors. The study presented here is an attempt to clarify the mechanism responsible for the change. Generalities are shown between the sensing mechanisms of different supporting materials loaded with rhodium, and sample-specific aspects that must be considered are identified. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Effects of Ag Additive in Low Temperature CO Detection with In2O3 Based Gas Sensors
Nanomaterials 2018, 8(10), 801; https://doi.org/10.3390/nano8100801
Received: 11 September 2018 / Revised: 4 October 2018 / Accepted: 5 October 2018 / Published: 8 October 2018
Cited by 2 | PDF Full-text (7257 KB) | HTML Full-text | XML Full-text
Abstract
Nanocomposites In2O3/Ag obtained by ultraviolet (UV) photoreduction and impregnation methods were studied as materials for CO sensors operating in the temperature range 25–250 °C. Nanocrystalline In2O3 and In2O3/Ag nanocomposites were characterized by [...] Read more.
Nanocomposites In2O3/Ag obtained by ultraviolet (UV) photoreduction and impregnation methods were studied as materials for CO sensors operating in the temperature range 25–250 °C. Nanocrystalline In2O3 and In2O3/Ag nanocomposites were characterized by X-ray diffraction (XRD), single-point Brunauer-Emmet-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) with energy dispersive X-ray (EDX) mapping. The active surface sites were investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy and thermo-programmed reduction with hydrogen (TPR-H2) method. Sensor measurements in the presence of 15 ppm CO demonstrated that UV treatment leads to a complete loss of In2O3 sensor sensitivity, while In2O3/Ag-UV nanocomposite synthesized by UV photoreduction demonstrates an increased sensor signal to CO at T < 200 °C. The observed high sensor response of the In2O3/Ag-UV nanocomposite at room temperature may be due to the realization of an additional mechanism of CO oxidation with participation of surface hydroxyl groups associated via hydrogen bonds. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Surface Properties of SnO2 Nanowires Deposited on Si Substrate Covered by Au Catalyst Studies by XPS, TDS and SEM
Nanomaterials 2018, 8(9), 738; https://doi.org/10.3390/nano8090738
Received: 27 July 2018 / Revised: 9 September 2018 / Accepted: 11 September 2018 / Published: 18 September 2018
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Abstract
The surface chemistry and the morphology of SnO2 nanowires of average length and diameter of several µm and around 100 nm, respectively, deposited by vapor phase deposition (VPD) method on Au-covered Si substrate, were studied before and after subsequent air exposure. For [...] Read more.
The surface chemistry and the morphology of SnO2 nanowires of average length and diameter of several µm and around 100 nm, respectively, deposited by vapor phase deposition (VPD) method on Au-covered Si substrate, were studied before and after subsequent air exposure. For this purpose, surface-sensitive methods, including X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS) and the scanning electron microscopy (SEM), were applied. The studies presented within this paper allowed to determine their surface non-stoichiometry combined with the presence of carbon contaminations, in a good correlation with their surface morphology. The relative concentrations of the main components [O]/[Sn]; [C]/[Sn]; [Au]/[Sn], together with the O–Sn; O–Si bonds, were analyzed. The results of TDS remained in a good agreement with the observations from XPS. Moreover, conclusions obtained for SnO2 nanowires deposited with the use of Au catalyst were compared to the previous obtained for Ag-assisted tin dioxide nanowires. The information obtained within these studies is of a great importance for the potential application of SnO2 nanowires in the field of novel chemical nanosensor devices, since the results can provide an interpretation of how aging effects influence gas sensor dynamic characteristics. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessArticle Zinc Oxide Coated Tin Oxide Nanofibers for Improved Selective Acetone Sensing
Nanomaterials 2018, 8(7), 509; https://doi.org/10.3390/nano8070509
Received: 25 May 2018 / Revised: 30 June 2018 / Accepted: 2 July 2018 / Published: 9 July 2018
Cited by 1 | PDF Full-text (3916 KB) | HTML Full-text | XML Full-text
Abstract
Three-dimensional hierarchical SnO2/ZnO hetero-nanofibers were fabricated by the electrospinning method followed with a low-temperature water bath treatment. These hierarchical hollow SnO2 nanofibers were assembled by the SnO2 nanoparticles through the electrospinning process and then the ZnO nanorods were grown [...] Read more.
Three-dimensional hierarchical SnO2/ZnO hetero-nanofibers were fabricated by the electrospinning method followed with a low-temperature water bath treatment. These hierarchical hollow SnO2 nanofibers were assembled by the SnO2 nanoparticles through the electrospinning process and then the ZnO nanorods were grown vertically on the surface of SnO2 nanoparticles, forming the 3D nanostructure. The synthesized hollow SnO2/ZnO heterojunctions nanofibers were further employed to be a gas-sensing material for detection of volatile organic compound (VOC) species such as acetone vapor, which is proposed as a gas biomarker for diabetes. It shows that the heterojunction nanofibers-based sensor exhibited excellent sensing properties to acetone vapor. The sensor shows a good selectivity to acetone in the interfering gases of ethanol, ammonia, formaldehyde, toluene, and methanol. The enhanced sensing performance may be due to the fact that n-n 3D heterojunctions, existing at the interface between ZnO nanorods and SnO2 particles in the SnO2/ZnO nanocomposites, could prompt significant changes in potential barrier height when exposed to acetone vapor, and gas-sensing mechanisms were analyzed and explained by Schottky barrier changes in SnO2/ZnO 3D hetero-nanofibers. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Review

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Open AccessReview Sensitivity-Selectivity Trade-Offs in Surface Ionization Gas Detection
Nanomaterials 2018, 8(12), 1017; https://doi.org/10.3390/nano8121017
Received: 20 November 2018 / Accepted: 29 November 2018 / Published: 6 December 2018
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Abstract
Surface ionization (SI) provides a simple, sensitive, and selective method for the detection of high-proton affinity substances, such as organic decay products, medical and illicit drugs as well as a range of other hazardous materials. Tests on different kinds of SI sensors showed [...] Read more.
Surface ionization (SI) provides a simple, sensitive, and selective method for the detection of high-proton affinity substances, such as organic decay products, medical and illicit drugs as well as a range of other hazardous materials. Tests on different kinds of SI sensors showed that the sensitivity and selectivity of such devices is not only dependent on the stoichiometry and nanomorphology of the emitter materials, but also on the shape of the electrode configurations that are used to read out the SI signals. Whereas, in parallel-plate capacitor devices, different kinds of emitter materials exhibit a high level of amine-selectivity, MEMS (micro-electro-mechanical-systems) and NEMS (nanowire) versions of SI sensors employing the same kinds of emitter materials provide significantly higher sensitivity, however, at the expense of a reduced chemical selectivity. In this paper, it is argued that such sensitivity-selectivity trade-offs arise from unselective physical ionization phenomena that occur in the high-field regions immediately adjacent to the surfaces of sharply curved MEMS (NEMS) emitter and collector electrodes. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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Open AccessReview Two-Dimensional Nanomaterials for Gas Sensing Applications: The Role of Theoretical Calculations
Nanomaterials 2018, 8(10), 851; https://doi.org/10.3390/nano8100851
Received: 1 October 2018 / Revised: 14 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
Cited by 1 | PDF Full-text (1592 KB) | HTML Full-text | XML Full-text
Abstract
Two-dimensional (2D) nanomaterials have attracted a large amount of attention regarding gas sensing applications, because of their high surface-to-volume ratio and unique chemical or physical gas adsorption capabilities. As an important research method, theoretical calculations have been massively applied in predicting the potentially [...] Read more.
Two-dimensional (2D) nanomaterials have attracted a large amount of attention regarding gas sensing applications, because of their high surface-to-volume ratio and unique chemical or physical gas adsorption capabilities. As an important research method, theoretical calculations have been massively applied in predicting the potentially excellent gas sensing properties of these 2D nanomaterials. In this review, we discuss the contributions of theoretical calculations in the study of the gas sensing properties of 2D nanomaterials. Firstly, we elaborate on the gas sensing mechanisms of 2D layered nanomaterials, such as the traditional charge transfer mechanism, and a standard for distinguishing between physical and chemical adsorption, from the perspective of theoretical calculations. Then, we describe how to conduct a theoretical analysis to explain or predict the gas sensing properties of 2D nanomaterials. Thirdly, we discuss three important methods that have been applied in order to improve the gas sensing properties, that is, defect functionalization (vacancy, edge, grain boundary, and doping), heterojunctions, and electric fields. Among these strategies, theoretical calculations play a very important role in explaining the mechanisms underlying the enhanced gas sensing properties. Finally, we summarize both the advantages and limitations of the theoretical calculations, and present perspectives for further research on the 2D nanomaterials-based gas sensors. Full article
(This article belongs to the Special Issue Development of Semiconductor Nanomaterials for Gas Sensors)
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