scholarly journals Graphene functionalised by laser-ablated V2O5 for a highly sensitive NH3 sensor

2017 ◽  
Vol 8 ◽  
pp. 571-578 ◽  
Author(s):  
Margus Kodu ◽  
Artjom Berholts ◽  
Tauno Kahro ◽  
Mati Kook ◽  
Peeter Ritslaid ◽  
...  
Keyword(s):  
Gas Adsorption ◽  
Gas Sensing ◽  
Metal Oxide Nanoparticles ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
Adsorption Sites ◽  
Time Sensitivity ◽  
Sensing Material ◽  
Induced Defects

Graphene has been recognized as a promising gas sensing material. The response of graphene-based sensors can be radically improved by introducing defects in graphene using, for example, metal or metal oxide nanoparticles. We have functionalised CVD grown, single-layer graphene by applying pulsed laser deposition (PLD) of V2O5 which resulted in a thin V2O5 layer on graphene with average thickness of ≈0.6 nm. From Raman spectroscopy, it was concluded that the PLD process also induced defects in graphene. Compared to unmodified graphene, the obtained chemiresistive sensor showed considerable improvement of sensing ammonia at room temperature. In addition, the response time, sensitivity and reversibility were essentially enhanced due to graphene functionalisation by laser deposited V2O5. This can be explained by an increased surface density of gas adsorption sites introduced by high energy atoms in laser ablation plasma and formation of nanophase boundaries between deposited V2O5 and graphene.

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.

Work function engineering of single layer graphene by irradiation-induced defects

2013 ◽  
Vol 103 (17) ◽  
pp. 171604 ◽  
Author(s):  
Jong-Hun Kim ◽  
Jin Heui Hwang ◽  
Joonki Suh ◽  
Sefaattin Tongay ◽  
Sangku Kwon ◽  
...  
Keyword(s):  
Work Function ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene ◽  
Induced Defects ◽  
Irradiation Induced Defects

High-energy collective electronic excitations in free-standing single-layer graphene

2013 ◽  
Vol 88 (7) ◽  
Author(s):  
P. Wachsmuth ◽  
R. Hambach ◽  
M. K. Kinyanjui ◽  
M. Guzzo ◽  
G. Benner ◽  
...  
Keyword(s):  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
Electronic Excitations ◽  
Free Standing ◽  
Layer Graphene

scholarly journals Интеркаляционный синтез силицидов кобальта под графеном, выращенным на карбиде кремния

2020 ◽  
Vol 62 (3) ◽  
pp. 462
Author(s):  
Г.С. Гребенюк ◽  
И.А. Елисеев ◽  
С.П. Лебедев ◽  
Е.Ю. Лобанова ◽  
Д.А. Смирнов ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Photoelectron Spectroscopy ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
High Energy Resolution ◽  
Kelvin Probe ◽  
Layer Graphene ◽  
Atomic Force ◽  
Cobalt Silicides

Abstract The process of formation of cobalt silicides near the graphene-silicon carbide interface by intercalation of single-layer graphene grown on the 4 H - and 6 H -SiC(0001) polytypes with cobalt and silicon is studied. The experiments were carried out in situ in ultrahigh vacuum. The analysis of the samples is performed by high-energy-resolution photoelectron spectroscopy using synchrotron radiation, low-energy electron diffraction, and also Raman spectroscopy, atomic-force and kelvin-probe microscopies. The thicknesses of the deposited cobalt and silicon layers is varied to 2 nm, and the sample temperature, from room temperature to 1000°C. Co and Si atoms deposited on heated samples is found to penetrate under graphene and are localized between the buffer layer and the substrate, which leads to a transformation of the buffer layer into additional graphene layer. It is shown that the result of intercalation of the system with cobalt and silicon is the formation under two-layer graphene of a Co–Si solid solution and silicide CoSi coated by the surface Co_3Si phase. It is shown that the thickness and the composition of the formed silicide films can be changed by varying the amount of the intercalated material and the order of their depositions.

Electrical Behavior of Graphene/SiO2/Silicon Material Irradiated by Electron for Field Effect Transistor (FET) Applications

2020 ◽  
Vol 1010 ◽  
pp. 339-345
Author(s):  
Ahmad Syahmi Zamzuri ◽  
Nur Idayu Ayob ◽  
Yusof Abdullah ◽  
Nur Ubaidah Saidin ◽  
Cik Rohaida Che Hak
Keyword(s):  
Single Layer ◽  
Chemical Vapor ◽  
Charge Trapping ◽  
High Energy ◽  
Single Layer Graphene ◽  
Electrical Characteristics ◽  
Current Voltage ◽  
Effect Transistor ◽  
High Energy Particles ◽  
Loop Form

In this paper, the detail study of electrical conductivity of single layer graphene (SLG) on silicon dioxide (SiO2)/Silicon substrate irradiated by high energy (MeV) electron is presented. The SLG samples prepared by Chemical Vapor Deposition (CVD) were irradiated by 50 kGy, 100 kGy and 200 kGy doses of electron radiation at energy voltage of 3 MeV. Current-Voltage (I-V) characteristics and conductivity of the pristine and irradiated graphene samples were measured and analysed using I-V measurement at room temperature. The non-linear I-V curves were clearly observed as the voltage reach to 2.0 V for non-irradiated and irradiated samples. This may be attributed to the non-uniform charges by high energy electron irradiation and poor metal contact of the sample. Hysteresis loop form at 2.0 V probably due to the to the charge trapping occurs at the interface of the graphene and SiO2. The reaction of high energy particles lead to creation of more carrier charges that contribute to the increment of conductivity compare to the small number of atom displacement of knock-on collisions with the nuclei of carbon atoms at higher dose. This study provides significant findings on the graphene electrical characteristics when irradiated with high energy (MeV) electron.

scholarly journals Preparation and Test of NH3 Gas Sensor Based on Single-Layer Graphene Film

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 965
Author(s):  
Ting Liang ◽  
Ruifang Liu ◽  
Cheng Lei ◽  
Kai Wang ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
Microelectromechanical Systems ◽  
Gas Sensing ◽  
Graphene Film ◽  
Single Layer ◽  
Chemical Vapor ◽  
Single Layer Graphene ◽  
Si Substrates ◽  
Ammonia Sensing ◽  
Layer Graphene ◽  
Mems Technology

The ammonia sensing properties of single-layer graphene synthesized by chemical vapor deposition (CVD) were studied. The Au interdigitated electrode (IDE) was prepared by microelectromechanical systems (MEMS) technology, and then, the single-layer graphene was transferred to the IDE by wet transfer technology. Raman spectroscopy was used to monitor the quality of graphene films transferred to SiO2/Si substrates. Moreover, the theory of graphene’s adsorption of gases is explained. The results show that gas sensing characteristics such as response/recovery time and response are related to the target gas, gas concentration, test temperature, and so on. In the stability test, the difference between the maximum resistance and the minimum resistance of the device is 1 ohm without ammonia, the change is less than 1% of its initial resistance, and the repeatability is up to 98.58%. Therefore, the sensor prepared with high quality single-layer graphene has good repeatability and stability for ammonia detection.

Acetylene Sensing Characteristics of SnO2 Nanowires

2015 ◽  
Vol 1119 ◽  
pp. 132-136
Author(s):  
Bing Wang
Keyword(s):  
Electron Microscopy ◽  
Thermal Evaporation ◽  
Gas Adsorption ◽  
Gas Sensing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Material ◽  
Transmission Electron ◽  
Mems Technology ◽  
Sensing Characteristics

SnO2 nanowires have been fabricated using thermal evaporation of the mixed powders of SnO2 and active carbon with Au catalysts. The morphology and structure of the prepared nanowires are determined on the basis of field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometer (EDS), x-ray diffraction (XRD) and transmission electron microscopy (TEM). The comb-shape interdigitating electrode made by MEMS technology is used to auxiliary investigating the gas sensing performance of the synthesized SnO2 nanowires. The SnO2 nanowires have sensing response to acetylene concentration of 1000 ppm under operated temperature of 300°C. The gas sensing mechanism is attributed to the gas adsorption and desorption processes occurring on the surface of the gas sensing material.

Effective fluorination of single-layer graphene by high-energy ion irradiation through a LiF overlayer

RSC Advances ◽  
2016 ◽  
Vol 6 (72) ◽  
pp. 68525-68529 ◽  
Author(s):  
Shiro Entani ◽  
Masaki Mizuguchi ◽  
Hideo Watanabe ◽  
Liubov Yu. Antipina ◽  
Pavel B. Sorokin ◽  
...  
Keyword(s):  
Chemical Method ◽  
Ion Irradiation ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
Heteroatom Doping ◽  
Layer Graphene

A new non-chemical method for heteroatom doping into single-layer graphene was demonstrated by high-energy ion irradiation of the graphene-based heterostructure.

scholarly journals Интеркалирование графена на карбиде кремния кобальтом

2019 ◽  
Vol 61 (7) ◽  
pp. 1374
Author(s):  
Г.С. Гребенюк ◽  
Е.Ю. Лобанова ◽  
Д.А. Смирнов ◽  
И.А. Елисеев ◽  
А.В. Зубов ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Single Layer ◽  
High Energy ◽  
Single Layer Graphene ◽  
High Energy Resolution ◽  
Cobalt Films ◽  
Cobalt Silicides

AbstractIn this paper, we studied cobalt intercalation of single-layer graphene grown on the 4 H -SiC(0001) polytype. The experiments were carried out in situ under ultrahigh vacuum conditions by high energy resolution photoelectron spectroscopy using synchrotron radiation and low energy electron diffraction. The nominal thicknesses of the deposited cobalt layers varied in the range of 0.2–5 nm, while the sample temperature was varied from room temperature to 800°C. Unlike Fe films, the annealing of Co films deposited on graphene at room temperature is shown to not intercalate graphene by cobalt. The formation of the graphene–cobalt–SiC intercalation system was detected upon deposition of Co atoms on samples heated to temperatures of above ~400°C. Cobalt films with a thickness up to 2 nm under graphene are formed using this method, and they are shown to be magnetized along the surface at thicknesses of greater than 1.3 nm. Graphene intercalation by cobalt was found to be accompanied by the chemical interaction of Co atoms with silicon carbide leading to the synthesis of cobalt silicides. At temperatures of above 500°C, the growth of cobalt films under graphene is limited by the diffusion of Co atoms into the bulk of silicon carbide.

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.

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