Research

10 pages, 3624 KiB

Open AccessCommunication

Pd-Decorated ZnO Hexagonal Microdiscs for NH₃ Sensor

by Yi Li, Boyu Zhang, Juan Li, Zaihua Duan, Yajie Yang, Zhen Yuan, Yadong Jiang and Huiling Tai

Chemosensors 2024, 12(3), 43; https://doi.org/10.3390/chemosensors12030043 - 05 Mar 2024

Cited by 1 | Viewed by 1063

Abstract

The NH₃ sensor is of great significance in preventing NH₃ leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal [...] Read more.

The NH₃ sensor is of great significance in preventing NH₃ leakage and ensuring life safety. In this work, the Pd-decorated ZnO hexagonal microdiscs are synthesized using hydrothermal and annealing processes, and the gas sensor is fabricated based on Pd-decorated ZnO hexagonal microdiscs. The gas-sensing test results show that the Pd-ZnO gas sensor has a good response to NH₃ gas. Specifically, it has a good linear response within 0.5–50 ppm NH₃ at the optimal operating temperature of 230 °C. In addition, the Pd-ZnO gas sensor exhibits good repeatability, short response time (23.2 s) and good humidity resistance (10–90% relative humidity). This work provides a useful reference for developing an NH₃ sensor. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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19 pages, 5003 KiB

Open AccessArticle

Surface-Catalyzed Zinc Oxide Nanorods and Interconnected Tetrapods as Efficient Methane Gas Sensing Platforms

by Abbey Knoepfel, Bed Poudel and Sanju Gupta

Chemosensors 2023, 11(9), 506; https://doi.org/10.3390/chemosensors11090506 - 17 Sep 2023

Viewed by 1158

Abstract

Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of [...] Read more.

Nanostructured metal oxide semiconductors have proven to be promising for the gas sensing domain. However, there are challenges associated with the fabrication of high-performance, low-to-room-temperature operation sensors for methane and other gases, including hydrogen sulfide, carbon dioxide, and ammonia. The functional properties of these semiconducting oxides can be improved by altering the morphology, crystal size, shape, and topology. Zinc oxide (ZnO) is an attractive option for gas sensing, but the need for elevated operating temperatures has limited its practical use as a commercial gas sensor. In this work, we prepared ZnO nanorod (ZnO-NR) arrays and interconnected tetrapod ZnO (T-ZnO) network sensing platforms as chemiresistive methane sensors on silicon substrates with platinum interdigitated electrodes and systematically characterized their methane sensing response in addition to their structural and physical properties. We also conducted surface modification by photochemical-catalyzed palladium, Pd, and Pd-Ag alloy nanoparticles and compared the uniformly distributed Pd decoration versus arrayed dots. The sensing performance was assessed in terms of target gas response magnitude (RM) and response percentage (R) recorded by changes in electrical resistance upon exposure to varying methane concentration (100–10,000 ppm) under thermal (operating temperatures = 175, 200, 230 °C) and optical (UV A, 365 nm illumination) excitations alongside response/recovery times, and limit of detection quantification. Thin film sensing platforms based on T-ZnO exhibited the highest response at 200 °C (RM = 2.98; R = 66.4%) compared to ZnO-NR thin films at 230 °C (RM = 1.34; R = 25.5%), attributed to the interconnected network and effective bandgap and barrier height reduction of the T-ZnO. The Pd-Ag-catalyzed and Pd dot-catalyzed T-ZnO films had the fastest response and recovery rates at 200 °C and room temperature under UV excitation, due to the localized Pd nanoparticles dots resulting in nano Schottky barrier formation, as opposed to the films coated with uniformly distributed Pd nanoparticles. The experimental findings present morphological differences, identify various mechanistic aspects, and discern chemical pathways for methane sensing. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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19 pages, 5795 KiB

Open AccessArticle

Microplotter Printing of Hierarchically Organized NiCo₂O₄ Films for Ethanol Gas Sensing

by Tatiana L. Simonenko, Nikolay P. Simonenko, Artem S. Mokrushin, Philipp Yu. Gorobtsov, Anna A. Lizunova, Oleg Yu. Grafov, Elizaveta P. Simonenko and Nikolay T. Kuznetsov

Chemosensors 2023, 11(2), 138; https://doi.org/10.3390/chemosensors11020138 - 14 Feb 2023

Cited by 6 | Viewed by 1664

Abstract

Using a combination of chemical coprecipitation and hydrothermal treatment of the resulting dispersed system, a hierarchically organized NiCo₂O₄ nanopowder was obtained, consisting of slightly elongated initial oxide nanoparticles self-organized into nanosheets about 10 nm thick, which in turn are combined [...] Read more.

Using a combination of chemical coprecipitation and hydrothermal treatment of the resulting dispersed system, a hierarchically organized NiCo₂O₄ nanopowder was obtained, consisting of slightly elongated initial oxide nanoparticles self-organized into nanosheets about 10 nm thick, which in turn are combined into hierarchical cellular agglomerates of about 2 μm. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HR-TEM) allowed to confirm the formation of NiCo₂O₄ powder with the desired crystal structure via additional heat treatment of the intermediate product. Energy-dispersive X-ray spectroscopy (EDX) was used to confirm the target metal ratio, and the uniform distribution of the elements (Ni, Co and O) was shown by mapping. The resulting nanopowder was employed to prepare functional inks suitable for microplotter printing of the NiCo₂O₄ film. It was found that an oxide film morphology is fully inherited from the hierarchically organized oxide nanopowder used. Atomic force microscopy (AFM) revealed the film thickness (15 μm) and determined the maximum height difference of 500 nm over an area of 25 μm². Kelvin probe force microscopy (KPFM) showed that the surface potential was shifted to the depths of the oxide film, and the work function value of the material surface was 4.54 eV, which is significantly lower compared to those reported in the literature. The electronic state of the elements in the NiCo₂O₄ film under study was analyzed by X-ray photoelectron spectroscopy (XPS). Chemosensor measurements showed that the printed receptor layer exhibited selectivity and high signal reproducibility for ethanol detection. As the relative humidity increases from 0 to 75%, the response value is reduced; however, the sensor response profile and signal-to-noise ratio remain without significant changes. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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13 pages, 3548 KiB

Open AccessArticle

Enhanced Sensing Performance of Electrospun Tin Dioxide Nanofibers Decorated with Cerium Dioxide Nanoparticles for the Detection of Liquefied Petroleum Gas

by Xichen Liu, Jianhua Zhang, Hao Zhang, Can Chen and Dongzhi Zhang

Chemosensors 2022, 10(12), 497; https://doi.org/10.3390/chemosensors10120497 - 23 Nov 2022

Cited by 3 | Viewed by 1377

Abstract

Tin dioxide (SnO₂) nanofibers and cerium dioxide (CeO₂) nanoparticles were prepared by electrospinning and hydrothermal methods, respectively. The morphology and structure of the synthesized SnO₂/CeO₂ samples were characterized by a variety of methods. The gas-sensing properties [...] Read more.

Tin dioxide (SnO₂) nanofibers and cerium dioxide (CeO₂) nanoparticles were prepared by electrospinning and hydrothermal methods, respectively. The morphology and structure of the synthesized SnO₂/CeO₂ samples were characterized by a variety of methods. The gas-sensing properties of the SnO₂/CeO₂ sensor were investigated for liquefied petroleum gas (LPG) detection at room temperature. Compared with pure SnO₂ nanofibers, the SnO₂/CeO₂ composite sensor showed a much higher response and shorter response time for LPG sensing after doping with CeO₂ nanoparticles. Furthermore, the SnO₂/CeO₂ composite sensor had better resistance to interference from humidity than the pure SnO₂ sensor. The significantly enhanced sensing performance of the SnO₂/CeO₂ composite sensor for LPG can be attributed to the modification with CeO₂ to increase oxygen vacancies and form a heterostructure with SnO₂ nanofibers. Meanwhile, the LPG detection circuit was built to realize real-time concentration display and alarm for practical applications. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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13 pages, 4813 KiB

Open AccessArticle

Effect of the Microstructure of ZnO Thin Films Prepared by PLD on Their Performance as Toxic Gas Sensors

by Didier Fasquelle, Stéphanie Députier, Valérie Bouquet and Maryline Guilloux-Viry

Chemosensors 2022, 10(7), 285; https://doi.org/10.3390/chemosensors10070285 - 16 Jul 2022

Cited by 6 | Viewed by 1672

Abstract

In 2008, the modified European Restriction of Hazardous Substances (RoHS) directive prohibited the use of hazardous substances such as lead, cadmium, and mercury. As such, an urgent need for lead-free components emerged in Europe. In this frame, we have decided to study the [...] Read more.

In 2008, the modified European Restriction of Hazardous Substances (RoHS) directive prohibited the use of hazardous substances such as lead, cadmium, and mercury. As such, an urgent need for lead-free components emerged in Europe. In this frame, we have decided to study the microstructure influence of zinc oxide thin films on the detection of hydrogen sulfide (H₂S). Zinc oxide thin films were deposited by PLD on silicon substrates under different conditions to modify the microstructure. In order to compare our demonstrators to current commercial semiconductor gas sensors, measurements under H₂S were also performed with sensors from Figaro and Winsen corporations. Gas sensors were therefore implemented by using commercial cases in view to test them with Simtronics gas detector DG477. The good sensitivity values measured at T = 400 °C under 100 ppm H₂S, and response times as low as 30 s, definitely confirm that ZnO thin films could be developed for commercial sensors. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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13 pages, 4965 KiB

Open AccessArticle

Adsorption Properties of ZSM-5 Molecular Sieve for Perfluoroisobutyronitrile Mixtures and Its Fluorocarbon Decomposition Products

by Wei Liu, Xinjie Qiu, Xiaoxing Zhang, Shuangshuang Tian, Zian Yuan and Weihao Liu

Chemosensors 2022, 10(4), 121; https://doi.org/10.3390/chemosensors10040121 - 24 Mar 2022

Cited by 6 | Viewed by 2295

Abstract

Perfluoroisobutyronitrile (C₄F₇N), an environment-friendly insulating gas, has excellent insulating properties and has the potential to be used in gas-insulated equipment when mixed with CO₂. Selecting suitable adsorption materials to adsorb the decomposition products of the C₄ [...] Read more.

Perfluoroisobutyronitrile (C₄F₇N), an environment-friendly insulating gas, has excellent insulating properties and has the potential to be used in gas-insulated equipment when mixed with CO₂. Selecting suitable adsorption materials to adsorb the decomposition products of the C₄F₇N mixture can ensure the safe and stable operation of the gas-insulated equipment and the personal safety of the operators in the electric power industry. The adsorption characteristics of the ZSM-5 molecular sieve on C₄F₇N and its five fluorocarbon decomposition products were investigated by adsorption experiments. The results show that the ZSM-5 molecular sieve has a certain adsorption effect on six fluorocarbon gases; the adsorption performance of C₃F₆ and C₃F₈ are the best, with an adsorption efficiency over 85%, while the concentration of CO₂ and C₄F₇N is affected by the ZSM-5 molecular sieve. At the same time, the paper based on the Metropolis Monte Carlo simulation of Materials Studio software found that the ZSM-5 molecular sieve has the strongest adsorption effect on C₄F₇N molecules and the weakest adsorption effect on CO₂ molecules. The stronger the polarity of the gas molecule, the more obvious the adsorption effect of molecular sieve structure on it. As a result, the ZSM-5 molecular sieve could be used in tail gas purification of insulated equipment, as well as to provide solutions for the development and production of protective equipment. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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9 pages, 3050 KiB

Open AccessArticle

Adsorption and Sensing Properties of Dissolved Gas in Oil on Cr-Doped InN Monolayer: A Density Functional Theory Study

by Guochao Qian, Jin Hu, Shan Wang, Weiju Dai and Qu Zhou

Chemosensors 2022, 10(1), 30; https://doi.org/10.3390/chemosensors10010030 - 12 Jan 2022

Cited by 6 | Viewed by 2015

Abstract

Dissolved gas analysis (DGA) is recognized as one of the most reliable methods in transformer fault diagnosis technology. In this paper, three characteristic gases of transformer oil (CO, C₂H₄, and CH₄) were used in conjunction with a [...] Read more.

Dissolved gas analysis (DGA) is recognized as one of the most reliable methods in transformer fault diagnosis technology. In this paper, three characteristic gases of transformer oil (CO, C₂H₄, and CH₄) were used in conjunction with a Cr-decorated InN monolayer according to first principle calculations. The adsorption performance of Cr–InN for these three gases were studied from several perspectives such as adsorption structures, adsorption energy, electron density, density of state, and band gap structure. The results revealed that the Cr–InN monolayer had good adsorption performance with CO and C₂H₄, while the band gap of the monolayer slightly changed after the adsorption of CO and C₂H₄. Additionally, the adsorption property of the Cr–InN monolayer on CH₄ was acceptable and a significant response was simultaneously generated. This paper provides the first insights regarding the possibility of Cr-doped InN monolayers for the detection of gases dissolved in oil. Full article

(This article belongs to the Special Issue The State-of-the-Art Gas Sensor)

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13 pages, 2897 KiB

Open AccessArticle

Au-Decorated WS₂ Microflakes Based Sensors for Selective Ammonia Detection at Room Temperature

by Qiyilan Guang, Baoyu Huang and Xiaogan Li

Chemosensors 2022, 10(1), 9; https://doi.org/10.3390/chemosensors10010009 - 27 Dec 2021

Cited by 17 | Viewed by 2992

Abstract

Gold nanoparticles decorated WS

_{2}

microflakes (Au/WS

_{2}

) have been synthesized by an in situ chemical reducing process. A chemiresistive-type sensor using as-synthesized Au/WS

_{2}

heterostructures as sensing materials shows an improved response to different concentrations of ammonia compared to pure WS [...] Read more.

Gold nanoparticles decorated WS

_{2}

microflakes (Au/WS

_{2}

) have been synthesized by an in situ chemical reducing process. A chemiresistive-type sensor using as-synthesized Au/WS

_{2}

heterostructures as sensing materials shows an improved response to different concentrations of ammonia compared to pure WS

_{2}

at room temperature. As the concentrations of gold nanoparticles increased in heterostructures, response/recovery speeds of the sensors became faster although the sensitivity of the sensor was compromised compared to the sensitivity of the sensor with lower concentrations of Au. In addition, the Au/WS

_{2}

-based sensor indicated excellent selectivity to formaldehyde, ethanol, benzene and acetone at room temperature. The improved performance of the sensors was attributed to the synergistic effect of electronic sensitization and chemical sensitization between WS