scholarly journals Sensitive Gas-Sensing by Creating Adsorption Active Sites: Coating an SnO2 Layer on Triangle Arrays

2018 ◽  
Vol 10 (34) ◽  
pp. 29092-29099 ◽  
Author(s):  
Shipu Xu ◽  
Yang Xu ◽  
Huaping Zhao ◽  
Rui Xu ◽  
Yong Lei
Keyword(s):  
Active Sites ◽  
Gas Sensing ◽  
Sno2 Layer

scholarly journals ZnO/RGO Heterojunction Based near Room Temperature Alcohol SENSOR with Improved Efficiency

2021 ◽  
Vol 6 (1) ◽  
pp. 25
Author(s):  
Sanghamitra Ghosal ◽  
Partha Bhattacharyya
Keyword(s):  
Active Sites ◽  
Room Temperature ◽  
Surface Engineering ◽  
Gas Sensing ◽  
Energy Band Diagram ◽  
Future Generation ◽  
High Yield ◽  
Synthesis Process ◽  
Ethanol Sensor ◽  
Vapor Sensing

The systematic optimization of surface engineering (dimensionality) indeed plays a crucial role in achieving efficient vapor-sensing performance. Among various semiconducting metal oxides, owing to some of its unique features and advantages, ZnO has attracted researchers on a global scale due to its application in various fields, including chemical sensors. The concomitant optimization of the surface attributes (varying different dimensions) of ZnO have become a sensation for the entire research community. Moreover, the small thickness and extremely large surface of exfoliated 2D nanosheets render the gas sensing material an ideal candidate for achieving strong coupling with different gas molecules. However, temperature is a crucial factor in the field of chemical sensing. Recently, graphene-based gas sensors have attracted attention due to their variety of structures, unique sensing performances and room temperature working conditions. In this work, a highly sensitive and fast responsive low temperature (60 °C)-based ethanol sensor, based on RGO/2D ZnO nanosheets hybrid structure, is reported. After detailed characterizations, the vapor sensing potentiality of this sensor was tested for the detection of ethanol. The ethanol sensor offered the response magnitude of 89% (100 ppm concentration) with response and recovery time of 12 s/29 s, respectively. Due to excessively high number of active sites for VOC interaction, with high yield synthesis process and appreciably high carrier mobility, this has paved the way for developing future generation, miniaturized and flexible (wearable) vapor sensor devices, meeting the multidimensional requirements for traditional and upcoming (health/medical sector) applications. The underlying mechanistic framework for vapor sensing, using this hybrid junction, is explained with the Energy Band Diagram.

scholarly journals Design and Synthesis of Novel 2D Porous Zinc Oxide-Nickel Oxide Composite Nanosheets for Detecting Ethanol Vapor

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1989
Author(s):  
Yuan-Chang Liang ◽  
Yen-Cheng Chang ◽  
Wei-Cheng Zhao
Keyword(s):  
Zinc Oxide ◽  
Nickel Oxide ◽  
Active Sites ◽  
Gas Sensing ◽  
Ethanol Vapor ◽  
Gas Diffusion ◽  
High Specific Surface Area ◽  
Sputtering Deposition ◽  
Vapor Sensing ◽  
Sensing Performance

The porous zinc oxide-nickel oxide (ZnO-NiO) composite nanosheets were synthesized via sputtering deposition of NiO thin film on the porous ZnO nanosheet templates. Various NiO film coverage sizes on porous ZnO nanosheet templates were achieved by changing NiO sputtering duration in this study. The microstructures of the porous ZnO-NiO composite nanosheets were investigated herein. The rugged surface feature of the porous ZnO-NiO composite nanosheets were formed and thicker NiO coverage layer narrowed the pore size on the ZnO nanosheet template. The gas sensors based on the porous ZnO-NiO composite nanosheets displayed higher sensing responses to ethanol vapor in comparison with the pristine ZnO template at the given target gas concentrations. Furthermore, the porous ZnO-NiO composite nanosheets with the suitable NiO coverage content demonstrated superior gas-sensing performance towards 50–750 ppm ethanol vapor. The observed ethanol vapor-sensing performance might be attributed to suitable ZnO/NiO heterojunction numbers and unique porous nanosheet structure with a high specific surface area, providing abundant active sites on the surface and numerous gas diffusion channels for the ethanol vapor molecules. This study demonstrated that coating of NiO on the porous ZnO nanosheet template with a suitable coverage size via sputtering deposition is a promising route to fabricate porous ZnO-NiO composite nanosheets with a high ethanol vapor sensing ability.

scholarly journals Breakthroughs in the Design of Novel Carbon-Based Metal Oxides Nanocomposites for VOCs Gas Sensing

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1485 ◽  
Author(s):  
Eleonora Pargoletti ◽  
Giuseppe Cappelletti
Keyword(s):  
Graphene Oxide ◽  
Active Sites ◽  
Gas Sensing ◽  
Spillover Effect ◽  
Gas Diffusion ◽  
Hybrid Features ◽  
Multi Wall Carbon Nanotubes ◽  
Recovery Times ◽  
Electron Migration ◽  
Carbon Based

Nowadays, the detection of volatile organic compounds (VOCs) at trace levels (down to ppb) is feasible by exploiting ultra-sensitive and highly selective chemoresistors, especially in the field of medical diagnosis. By coupling metal oxide semiconductors (MOS e.g., SnO2, ZnO, WO3, CuO, TiO2 and Fe2O3) with innovative carbon-based materials (graphene, graphene oxide, reduced graphene oxide, single-wall and multi-wall carbon nanotubes), outstanding performances in terms of sensitivity, selectivity, limits of detection, response and recovery times towards specific gaseous targets (such as ethanol, acetone, formaldehyde and aromatic compounds) can be easily achieved. Notably, carbonaceous species, highly interconnected to MOS nanoparticles, enhance the sensor responses by (i) increasing the surface area and the pore content, (ii) favoring the electron migration, the transfer efficiency (spillover effect) and gas diffusion rate, (iii) promoting the active sites concomitantly limiting the nanopowders agglomeration; and (iv) forming nano-heterojunctions. Herein, the aim of the present review is to highlight the above-mentioned hybrid features in order to engineer novel flexible, miniaturized and low working temperature sensors, able to detect specific VOC biomarkers of a human’s disease.

Nanomaterial-based gas sensors used for breath diagnosis

2020 ◽  
Vol 8 (16) ◽  
pp. 3231-3248 ◽  
Author(s):  
Xinyuan Zhou ◽  
Zhenjie Xue ◽  
Xiangyu Chen ◽  
Chuanhui Huang ◽  
Wanqiao Bai ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Gas Sensors ◽  
Active Sites ◽  
Gas Sensing ◽  
High Surface ◽  
Volume Ratio ◽  
Sensing Applications ◽  
Enormous Number

Gas-sensing applications commonly use nanomaterials (NMs) because of their unique physicochemical properties, including a high surface-to-volume ratio, enormous number of active sites, controllable morphology, and potential for miniaturisation.

Enhanced NO2 sensing performance of S-doped biomorphic SnO2 with increased active sites and charge transfer at room temperature

2020 ◽  
Vol 7 (10) ◽  
pp. 2031-2042
Author(s):  
Wenna Li ◽  
Lang He ◽  
Xue Bai ◽  
Lujia Liu ◽  
Muhammad Ikram ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Active Sites ◽  
Room Temperature ◽  
Gas Sensing ◽  
Chemical Bonds ◽  
Sensing Performance

S-Doped biomorphic SnO2 with active S-terminations and S–Sn–O chemical bonds has significantly improved gas sensing performance to NO2 at room temperature.

Novel nanoparticle catalysts for catalytic gas sensing

2016 ◽  
Vol 6 (2) ◽  
pp. 339-348 ◽  
Author(s):  
Eva Morsbach ◽  
Sebastian Kunz ◽  
Marcus Bäumer
Keyword(s):  
Active Sites ◽  
Gas Sensing ◽  
Catalytic Properties ◽  
Hydrogen Sensor ◽  
Colloidal Nanoparticles ◽  
Nanoparticle Catalysts ◽  
Porous Networks ◽  
Bifunctional Ligands ◽  
Catalytically Active ◽  
Total Heat Capacity

Applications such as catalytic gas sensing require a high density of catalytically active sites at low total heat capacity. One way to achieve this goal is the molecular linkage of colloidal nanoparticles with bifunctional ligands resulting in 3D-porous networks. The catalytic properties of such structures were investigated in a thermoelectric hydrogen sensor.

scholarly journals Berlin Green Framework-Based Gas Sensor for Room-Temperature and High-Selectivity Detection of Ammonia

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Tingqiang Yang ◽  
Lingfeng Gao ◽  
Wenxuan Wang ◽  
Jianlong Kang ◽  
Guanghui Zhao ◽  
...  
Keyword(s):  
High Resistance ◽  
Active Sites ◽  
Density Functional ◽  
Room Temperature ◽  
High Selectivity ◽  
Gas Sensing ◽  
Response Recovery ◽  
Sensing Material ◽  
Agriculture Industry ◽  
Ammonia Detection

AbstractAmmonia detection possesses great potential in atmosphere environmental protection, agriculture, industry, and rapid medical diagnosis. However, it still remains a great challenge to balance the sensitivity, selectivity, working temperature, and response/recovery speed. In this work, Berlin green (BG) framework is demonstrated as a highly promising sensing material for ammonia detection by both density functional theory simulation and experimental gas sensing investigation. Vacancy in BG framework offers abundant active sites for ammonia absorption, and the absorbed ammonia transfers sufficient electron to BG, arousing remarkable enhancement of resistance. Pristine BG framework shows remarkable response to ammonia at 50–110 °C with the highest response at 80 °C, which is jointly influenced by ammonia's absorption onto BG surface and insertion into BG lattice. The sensing performance of BG can hardly be achieved at room temperature due to its high resistance. Introduction of conductive Ti3CN MXene overcomes the high resistance of pure BG framework, and the simply prepared BG/Ti3CN mixture shows high selectivity to ammonia at room temperature with satisfying response/recovery speed.

scholarly journals Fabrication of n-ZnO/p-Si++ Hetero-junction Devices for Hydrogen Detection: Effect of Annealing Temperature

2021 ◽  
Author(s):  
Vinod Kumar ◽  
Ishpal Rawal ◽  
Vipin Kumar
Keyword(s):  
Grain Boundary ◽  
Specific Surface ◽  
Crystallite Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Annealing Temperature ◽  
Gas Sensing ◽  
Ambient Air ◽  
Hydrogen Gas

Abstract In the present study, we reports the fabrication of n-ZnO/p-Si++ hetero-junction devices for the detection of hydrogen leakage in ambient air environment. For the fabrication of n-ZnO/p-Si++ hetero-junction devices, high quality ZnO thin films are grown by controlled thermal evaporation technique on the highly doped p-type silicon substrates at 400 oC. The two sets of films deposited at 400 o C are further annealed at 500 and 600 oC to examine the effect of annealing temperature on the structural, morphology, electrical and gas sensing properties of the deposited films. It is revealed from the x-ray diffraction studies that the crystallite size, and the density of the films increase from 22.55 to 24.95 nm, from 5.65 to 5.68 g/cm3, respectively, on increasing the fabrication temperature from 400 to 600 oC. In contrast to it, the grain boundary specific surface area decrease from 8.79 x107 to 7.88 x107 m-1 on changing the fabrication temperature from 400 to 600 oC. The hydrogen gas sensing response of the fabricated devices has also been recorded at different operating temperatures and different hydrogen concentrations (200 to 1000ppm) in air ambient. It is found that the gas sensing response of the fabricated devices increase with increase in operating temperature (up to 100 oC) and decease beyond this temperature. The gas sensing responses of the devices fabricated at 400, 500 and 600 oC are found to be 97.22, 64.23 and 40.77 % at 1000 ppm of hydrogen. A decrease in gas sensing response with fabrication temperature is attributed to the increase in crystallite size (quantum size effect), density of films (i.e. lower penetration) and decrease in grain boundary specific surface area (i.e. active sites) with annealing temperature. The mechanism of the gas sensing in these devices has also been systematically analyzed under different models.

UV-enhanced NO2 gas sensors based on In2O3/ZnO composite material modified by polypeptides

2021 ◽  
Author(s):  
Zhihua Ying ◽  
Teng Zhang ◽  
Chao Feng ◽  
Fei Wen ◽  
Lili Li ◽  
...  
Keyword(s):  
Composite Material ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Active Sites ◽  
High Performance ◽  
Gas Sensing ◽  
Uv Light ◽  
Gas Concentration ◽  
One Step ◽  
Strong Linear Relationship

Abstract This present study reported a high-performance gas sensor, based on In2O3/ZnO composite material modified by polypeptides, with a high sensibility to NO2, where the In2O3/ZnO composite was prepared by a one-step hydrothermal method. A series of results through material characterization technologies showed the addition of polypeptides can effectively change the morphology and size of In2O3/ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In2O3/ZnO composite modified by polypeptides increased the active sites on the surface. At the same time, the gas sensing properties of four different ratios of polypeptide-modified In2O3/ZnO gas sensors were tested. It was found that the In2O3/ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In2O3/ZnO-10 gas sensor showed a strong linear relationship with the NO2 gas concentration. When the NO2 gas concentration was 20 ppm, the response time was as quick as 19s, and the recovery time was 57s. Finally, based on the obtained experimental characterization results and energy band structure analysis, a possible gas sensing mechanism is proposed.

Rational Synthesis and Optimization of Multifunctional Solid-State Gas Sensors

2004 ◽  
Vol 828 ◽  
Author(s):  
Johannes Schwank ◽  
Ghenadii Korotcenkov
Keyword(s):  
Solid State ◽  
Gas Sensors ◽  
Active Sites ◽  
Gas Sensing ◽  
Heterogeneous Systems ◽  
Sensor Applications ◽  
Sensing Applications ◽  
Long Time ◽  
Overall Performance ◽  
Scale Design

ABSTRACTA new approach is discussed for the rational synthesis and development of optimized multifunctional solid-state gas sensors. Multifunctionality—the incorporation of multiple types of reactivities into a material, such as acid and/or base functionalities, oxidation and/or reduction functionalities, etc.—isa requirement in many gas sensing applications. The front end of many gas sensors contains catalytic layers, so that optimization of catalysts and optimization of gas sensors can be carried out in a synergistic fashion.Multifunctionality presents unique challenges to rational catalyst and sensor systems development because the overall performance of the material is a convolution of the performance of the various subcomponents, and optimization of these individual subcomponents in isolation does not necessarily lead to optimal, or even acceptable, overall performance. A major obstacle to dealing with these difficulties is the inherent complexity of heterogeneous systems prepared by traditional approaches, which makes it difficult to unambiguously identify the compositions and morphologies of the local active sites and their interactions. Further complicating the problem is the requirement to function in environments that can vary on both short and long time scales. A key to understanding, controlling, and optimizing these materials is the ability to produce and study well-defined sensor materials with well-defined composition and morphology, with the flexibility to vary the composition easily without jeopardizing the structural uniformity.The development of new or improved materials for gas sensor applications requires a search for novel and innovative approaches to the nano-scale design of these materials. The use of the technology of surface modification by successive ionic layer deposition (SILD) method is such an innovative approach that will be discussed in this paper.

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