scholarly journals Polymer-Templated Durable and Hydrophobic Nanostructures for Hydrogen Gas Sensing Applications

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4470
Author(s):  
Mohammad Kamal Hossain ◽  
Qasem Ahmed Drmosh
Keyword(s):  
Contact Angle ◽  
Surface Area ◽  
Gas Adsorption ◽  
Sessile Drop ◽  
Gas Sensing ◽  
Hydrogen Gas ◽  
Adsorption Sites ◽  
Wetting Contact Angle ◽  
Sensing Applications ◽  
Surface Nanostructures

A simple and hands-on one-step process has been implemented to fabricate polymer-templated hydrophobic nanostructures as hydrogen gas sensing platforms. Topographic measurements have confirmed irregular hills and dips of various dimensions that are responsible for creating air bubble pockets that satisfy the Cassie–Baxter state of hydrophobicity. High-resolution field-emission scanning electron microscopy (FESEM) has revealed double-layer structures consisting of fine microscopic flower-like structures of nanoscale petals on the top of base nanostructures. Wetting contact angle (WCA) measurements further revealed the contact angle to be ~142.0° ± 10.0°. Such hydrophobic nanostructures were expected to provide a platform for gas-sensing materials of a higher surface area. From this direction, a very thin layer of palladium, ca. 100 nm of thickness, was sputtered. Thereafter, further topographic and WCA measurements were carried out. FESEM micrographs revealed that microscopic flower-like structures of nanoscale petals remained intact. A sessile drop test reconfirmed a WCA of as high as ~130.0° ± 10.0°. Due to the inherent features of hydrophobic nanostructures, a wider surface area was expected that can be useful for higher target gas adsorption sites. In this context, a customized sensing facility was set up, and H2 gas sensing performance was carried out. The surface nanostructures were found to be very stable and durable over the course of a year and beyond. A polymer-based hydrophobic gas-sensing platform as investigated in this study will play a dual role in hydrophobicity as well as superior gas-sensing characteristics.

scholarly journals Gas Adsorption Investigation on SiGe Monolayer: A First-Principle Calculation

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2879
Author(s):  
Xiang Sun ◽  
Yuzheng Guo ◽  
Yan Zhao ◽  
Sheng Liu ◽  
Hui Li
Keyword(s):  
Gas Adsorption ◽  
Gas Sensing ◽  
First Principles Calculation ◽  
First Principle Calculation ◽  
Adsorption Sites ◽  
Sensing Applications ◽  
Adsorption Behaviors ◽  
Sensing Material ◽  
Nh3 Adsorption ◽  
No2 Adsorption

The gas adsorption behaviors of CO, CO2, SO2, NO2, NO, NH3, H2, H2O, and O2 on SiGe monolayer are studied using the first-principles calculation method. Three special adsorption sites and different gas molecule orientations are considered. Based on adsorption energy, band gap, charge transfer, and the electron localization function, the appropriate physical adsorptions of SO2, NO, NH3, and O2 are confirmed. These gases possess excellent adsorption properties that demonstrate the obvious sensitiveness of SiGe monolayer to these gases. Moreover, SiGe may be used as a sensing material for some of them. NO2 adsorption in different adsorption sites can be identified as chemical adsorption. Besides, the external electric field can effectively modify the adsorption strength. The range of 0 ~ − 2 V/nm can create a desorption effect when NH3 adsorbs at the Ge site. The NH3 adsorption models on Ge site are chosen to investigate the properties of the I-V curve. Our theoretical results indicate that SiGe monolayer is a promising candidate for gas sensing applications.

scholarly journals Carbon dioxide adsorption and interaction with formation fluids of Jordanian unconventional reservoirs

2021 ◽  
Author(s):  
H. Samara ◽  
T. V. Ostrowski ◽  
F. Ayad Abdulkareem ◽  
E. Padmanabhan ◽  
P. Jaeger
Keyword(s):  
Carbon Dioxide ◽  
Contact Angle ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Gas Adsorption ◽  
Sessile Drop ◽  
Global Climate ◽  
Gravimetric Method ◽  
Rock Surface ◽  
Operating Pressure

AbstractShales are mostly unexploited energy resources. However, the extraction and production of their hydrocarbons require innovative methods. Applications involving carbon dioxide in shales could combine its potential use in oil recovery with its storage in view of its impact on global climate. The success of these approaches highly depends on various mechanisms taking place in the rock pores simultaneously. In this work, properties governing these mechanisms are presented at technically relevant conditions. The pendant and sessile drop methods are utilized to measure interfacial tension and wettability, respectively. The gravimetric method is used to quantify CO2 adsorption capacity of shale and gas adsorption kinetics is evaluated to determine diffusion coefficients. It is found that interfacial properties are strongly affected by the operating pressure. The oil-CO2 interfacial tension shows a decrease from approx. 21 mN/m at 0.1 MPa to around 3 mN/m at 20 MPa. A similar trend is observed in brine-CO2 systems. The diffusion coefficient is observed to slightly increase with pressure at supercritical conditions. Finally, the contact angle is found to be directly related to the gas adsorption at the rock surface: Up to 3.8 wt% of CO2 is adsorbed on the shale surface at 20 MPa and 60 °C where a maximum in contact angle is also found. To the best of the author’s knowledge, the affinity of calcite-rich surfaces toward CO2 adsorption is linked experimentally to the wetting behavior for the first time. The results are discussed in terms of CO2 storage scenarios occurring optimally at 20 MPa.

scholarly journals Tuning Stoichiometry and Structure of Pd-WO3−x Thin Films for Hydrogen Gas Sensing by High-Power Impulse Magnetron Sputtering

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5101
Author(s):  
Nirmal Kumar ◽  
Stanislav Haviar ◽  
Jiří Rezek ◽  
Pavel Baroch ◽  
Petr Zeman
Keyword(s):  
Magnetron Sputtering ◽  
High Power ◽  
Gas Sensing ◽  
Pulse Length ◽  
Pd Nanoparticles ◽  
Hydrogen Gas ◽  
Sensory Response ◽  
Hydrogen Sensing ◽  
Sensing Applications ◽  
Deposition Parameters

By tuning the deposition parameters of reactive high-power impulse magnetron sputtering, specifically the pulse length, we were able to prepare WO3−x films with various stoichiometry and structure. Subsequently, the films were annealed in air at moderate temperature (350 °C). We demonstrate that the stoichiometry of the as-deposited films influences considerably the type of crystalline phase formed in the annealed films. The appropriate sub-stoichiometry of the films (approx. WO2.76) enabled crystallization of the monoclinic phase during the annealing. This phase is favorable for hydrogen sensing applications. To characterize the sensory behavior of the films, the tungsten oxide films were decorated by Pd nanoparticles before annealing and were assembled as a conductometric gas sensor. The sensory response of the films that crystallized in the monoclinic structure was proven to be superior to that of the films containing other phases.

scholarly journals An Analytical Conductance Model for Gas Detection Based on a Zigzag Carbon Nanotube Sensor

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 357
Author(s):  
Ali Hosseingholipourasl ◽  
Sharifah Hafizah Syed Ariffin ◽  
Mohammad Taghi Ahmadi ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Band Structure ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
Electrical Conductance ◽  
Analytical Models ◽  
Adsorption Effect ◽  
Sensing Applications ◽  
New Energy ◽  
Gas Molecules

Recent advances in nanotechnology have revealed the superiority of nanocarbon species such as carbon nanotubes over other conventional materials for gas sensing applications. In this work, analytical modeling of the semiconducting zigzag carbon nanotube field-effect transistor (ZCNT-FET) based sensor for the detection of gas molecules is demonstrated. We propose new analytical models to strongly simulate and investigate the physical and electrical behavior of the ZCNT sensor in the presence of various gas molecules (CO2, H2O, and CH4). Therefore, we start with the modeling of the energy band structure by acquiring the new energy dispersion relation for the ZCNT and introducing the gas adsorption effects to the band structure model. Then, the electrical conductance of the ZCNT is modeled and formulated while the gas adsorption effect is considered in the conductance model. The band structure analysis indicates that, the semiconducting ZCNT experiences band gap variation after the adsorption of the gases. Furthermore, the bandgap variation influences the conductance of the ZCNT and the results exhibit increments of the ZCNT conductance in the presence of target gases while the minimum conductance shifted upward around the neutrality point. Besides, the I-V characteristics of the sensor are extracted from the conductance model and its variations after adsorption of different gas molecules are monitored and investigated. To verify the accuracy of the proposed models, the conductance model is compared with previous experimental and modeling data and a good consensus is observed. It can be concluded that the proposed analytical models can successfully be applied to predict sensor behavior against different gas molecules.

ZnAl2 O4 -Functionalized Zinc Oxide Microstructures for Highly Selective Hydrogen Gas Sensing Applications

2018 ◽  
Vol 215 (7) ◽  
pp. 1700772 ◽  
Author(s):  
Mathias Hoppe ◽  
Oleg Lupan ◽  
Vasile Postica ◽  
Niklas Wolff ◽  
Viola Duppel ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Gas Sensing ◽  
Hydrogen Gas ◽  
Sensing Applications

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.

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