scholarly journals Recent Developments in Graphene-Based Toxic Gas Sensors: A Theoretical Overview

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1992
Author(s):  
Heriberto Cruz-Martínez ◽  
Hugo Rojas-Chávez ◽  
Fernando Montejo-Alvaro ◽  
Yesica A. Peña-Castañeda ◽  
Pastor T. Matadamas-Ortiz ◽  
...  
Keyword(s):  
Gas Sensors ◽  
High Performance ◽  
Experimental Investigations ◽  
Pristine Graphene ◽  
First Principle ◽  
Toxic Gases ◽  
Recent Developments ◽  
Doped Graphene ◽  
Toxic Gas ◽  
Theoretical Results

Detecting and monitoring air-polluting gases such as carbon monoxide (CO), nitrogen oxides (NOx), and sulfur oxides (SOx) are critical, as these gases are toxic and harm the ecosystem and the human health. Therefore, it is necessary to design high-performance gas sensors for toxic gas detection. In this sense, graphene-based materials are promising for use as toxic gas sensors. In addition to experimental investigations, first-principle methods have enabled graphene-based sensor design to progress by leaps and bounds. This review presents a detailed analysis of graphene-based toxic gas sensors by using first-principle methods. The modifications made to graphene, such as decorated, defective, and doped to improve the detection of NOx, SOx, and CO toxic gases are revised and analyzed. In general, graphene decorated with transition metals, defective graphene, and doped graphene have a higher sensibility toward the toxic gases than pristine graphene. This review shows the relevance of using first-principle studies for the design of novel and efficient toxic gas sensors. The theoretical results obtained to date can greatly help experimental groups to design novel and efficient graphene-based toxic gas sensors.

scholarly journals Nitrogen Dioxide Gas Sensor Based on Ag-Doped Graphene: A First-Principle Study

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 227
Author(s):  
Qichao Li ◽  
Yamin Liu ◽  
Di Chen ◽  
Jianmin Miao ◽  
Xiao Zhi ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
High Performance ◽  
Density Functional ◽  
Noble Metals ◽  
Gas Sensing ◽  
Mulliken Charge ◽  
Chronic Obstructive ◽  
Doped Graphene ◽  
The Impact

High-performance tracking trace amounts of NO2 with gas sensors could be helpful in protecting human health since high levels of NO2 may increase the risk of developing acute exacerbation of chronic obstructive pulmonary disease. Among various gas sensors, Graphene-based sensors have attracted broad attention due to their sensitivity, particularly with the addition of noble metals (e.g., Ag). Nevertheless, the internal mechanism of improving the gas sensing behavior through doping Ag is still unclear. Herein, the impact of Ag doping on the sensing properties of Graphene-based sensors is systematically analyzed via first principles. Based on the density-functional theory (DFT), the adsorption behavior of specific gases (NO2, NH3, H2O, CO2, CH4, and C2H6) on Ag-doped Graphene (Ag–Gr) is calculated and compared. It is found that NO2 shows the strongest interaction and largest Mulliken charge transfer to Ag–Gr among these studied gases, which may directly result in the highest sensitivity toward NO2 for the Ag–Gr-based gas sensor.

scholarly journals Theoretical Study on the Quantum Capacitance Origin of Graphene Cathodes in Lithium Ion Capacitors

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 444 ◽  
Author(s):  
Fangyuan Su ◽  
Li Huo ◽  
Qingqiang Kong ◽  
Lijing Xie ◽  
Chengmeng Chen
Keyword(s):  
High Performance ◽  
Lithium Ion ◽  
Quantum Capacitance ◽  
Storage Device ◽  
Pristine Graphene ◽  
Voltage Range ◽  
Energy Conversion And Storage ◽  
Doped Graphene ◽  
And Storage ◽  
Important Character

Quantum capacitance (QC) is a very important character of the graphene cathode in lithium ion capacitors (LIC), which is a novel kind of electrochemical energy conversion and storage device. However, the QC electronic origin of the graphene cathode, which will affect the electrochemical reaction at the electrode/electrolyte interface, is still unclear. In this article, the QC of various kinds of graphene cathode is investigated systematically by DFT calculation. It was found that the value and origin of QC strongly depend on the defects and alien atoms of graphene. Graphene with pentagon defects possesses a higher QC than pristine graphene due to the contribution from the electronic states localized at the carbon pentagon. The introduction of graphitic B can contribute to QC, while graphitic N and P does not work in the voltage range of the LIC cathode. Single vacant defect graphene and pyrrolic N-doped graphene demonstrate very high QC due to the presence of states associated with the σ orbital of unbonded carbon atoms. However, pyridinic graphene shows an even higher QC because of the states from the N atom. For the residual O in graphene, its QC mainly originated from the pz states of carbon atoms and the effect of O, especially the O in bridged oxygen functional group (–COC–), is very limited. These results provide new insight into further study of the catalytic behavior and the design of a high performance graphene cathode for LIC.

The Development of the Remote Wireless Monitoring Device for Toxic Gases

2013 ◽  
Vol 846-847 ◽  
pp. 415-420
Author(s):  
Da Wu ◽  
Ling Qiao Zhu ◽  
Jun Tang ◽  
Tao Jiang ◽  
Zhi Min Li ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Gas Sensors ◽  
Wireless Sensor ◽  
Low Power Consumption ◽  
Cost Performance ◽  
Wireless Monitoring ◽  
Toxic Gases ◽  
Gas Leak ◽  
Sensor Module ◽  
Toxic Gas

For the scene where there is a toxic gas leak, in order to detect the gas quickly and safely and make the effective solutions, the project of monitoring toxic gases in a remote wireless way and the process of the development is proposed in this paper. The device developed in this paper includes several wireless sensor network (WSN) nodes and one hand-held terminal, and the sensor module of WSN node is composed of several chemical gas sensors. The nodes will be sent to the scene by ground robots or unmanned aerial vehicles and make up the WSN monitoring system automatically, to achieve an aim of monitoring the toxic gas in real time. The experiment results show that the device can deal with the emergencies about the leak of toxic gas efficiently. And it has the advantages of low power consumption, high cost performance, self-forming network, anti-interference. Its suitable to monitor the toxic gas in various environments of industrial production and chemical scene of accident and unexpected occasions where there is a leak of toxic gas.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

What Can Digitization Do For Formulated Product Innovation and Development

2020 ◽  
Author(s):  
James McDonagh ◽  
William Swope ◽  
Richard L. Anderson ◽  
Michael Johnston ◽  
David J. Bray
Keyword(s):  
High Performance ◽  
Quality Data ◽  
High Quality Data ◽  
Base Level ◽  
Hybrid Approaches ◽  
Digital Ecosystem ◽  
Recent Developments ◽  
Chemical Simulation ◽  
High Level ◽  
Physical And Chemical

Digitization offers significant opportunities for the formulated product industry to transform the way it works and develop new methods of business. R&D is one area of operation that is challenging to take advantage of these technologies due to its high level of domain specialisation and creativity but the benefits could be significant. Recent developments of base level technologies such as artificial intelligence (AI)/machine learning (ML), robotics and high performance computing (HPC), to name a few, present disruptive and transformative technologies which could offer new insights, discovery methods and enhanced chemical control when combined in a digital ecosystem of connectivity, distributive services and decentralisation. At the fundamental level, research in these technologies has shown that new physical and chemical insights can be gained, which in turn can augment experimental R&D approaches through physics-based chemical simulation, data driven models and hybrid approaches. In all of these cases, high quality data is required to build and validate models in addition to the skills and expertise to exploit such methods. In this article we give an overview of some of the digital technology demonstrators we have developed for formulated product R&D. We discuss the challenges in building and deploying these demonstrators.<br>

scholarly journals Optimization of a Low-Power Chemoresistive Gas Sensor: Predictive Thermal Modelling and Mechanical Failure Analysis

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 783 ◽  
Author(s):  
Andrea Gaiardo ◽  
David Novel ◽  
Elia Scattolo ◽  
Michele Crivellari ◽  
Antonino Picciotto ◽  
...  
Keyword(s):  
Low Power ◽  
Failure Analysis ◽  
Gas Sensors ◽  
High Performance ◽  
Gas Sensing ◽  
Mechanical Failure ◽  
Sensing Applications ◽  
Theoretical Approaches ◽  
Sensing Material ◽  
Silicon Bulk

The substrate plays a key role in chemoresistive gas sensors. It acts as mechanical support for the sensing material, hosts the heating element and, also, aids the sensing material in signal transduction. In recent years, a significant improvement in the substrate production process has been achieved, thanks to the advances in micro- and nanofabrication for micro-electro-mechanical system (MEMS) technologies. In addition, the use of innovative materials and smaller low-power consumption silicon microheaters led to the development of high-performance gas sensors. Various heater layouts were investigated to optimize the temperature distribution on the membrane, and a suspended membrane configuration was exploited to avoid heat loss by conduction through the silicon bulk. However, there is a lack of comprehensive studies focused on predictive models for the optimization of the thermal and mechanical properties of a microheater. In this work, three microheater layouts in three membrane sizes were developed using the microfabrication process. The performance of these devices was evaluated to predict their thermal and mechanical behaviors by using both experimental and theoretical approaches. Finally, a statistical method was employed to cross-correlate the thermal predictive model and the mechanical failure analysis, aiming at microheater design optimization for gas-sensing applications.

scholarly journals N-doped graphene foam obtained by microwave-assisted exfoliation of graphite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Malgorzata Skorupska ◽  
Anna Ilnicka ◽  
Jerzy P. Lukaszewicz
Keyword(s):  
Electron Microscopy ◽  
Electrode Materials ◽  
Elemental Content ◽  
Research Approach ◽  
Pristine Graphene ◽  
Active Electrode ◽  
Graphene Foam ◽  
Practical Applications ◽  
Microwave Reactor ◽  
Doped Graphene

AbstractThe synthesis of metal-free but electrochemically active electrode materials, which could be an important contributor to environmental protection, is the key motivation for this research approach. The progress of graphene material science in recent decades has contributed to the further development of nanotechnology and material engineering. Due to the unique properties of graphene materials, they have found many practical applications: among others, as catalysts in metal-air batteries, supercapacitors, or fuel cells. In order to create an economical and efficient material for energy production and storage applications, researchers focused on the introduction of additional heteroatoms to the graphene structure. As solutions for functionalizing pristine graphene structures are very difficult to implement, this article presents a facile method of preparing nitrogen-doped graphene foam in a microwave reactor. The influence of solvent type and microwave reactor holding time was investigated. To characterize the elemental content and structural properties of the obtained N-doped graphene materials, methods such as elemental analysis, high-resolution transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy were used. Electrochemical activity in ORR of the obtained materials was tested using cyclic voltamperometry (CV) and linear sweep voltamperometry (LSV). The tests proved the materials’ high activity towards ORR, with the number of electrons reaching 3.46 for tested non-Pt materials, while the analogous value for the C-Pt (20 wt% loading) reference was 4.

Sulfur vacancies in Co9S8-x/N-doped graphene enhancing electrochemical kinetics to high-performance lithium sulfur batteries

2021 ◽  
Author(s):  
Haojie Li ◽  
Yihua Song ◽  
Kai Xi ◽  
Wei Wang ◽  
Sheng Liu ◽  
...  
Keyword(s):  
Cathode Materials ◽  
High Performance ◽  
Catalytic Conversion ◽  
High Energy ◽  
Electrochemical Kinetics ◽  
Lithium Sulfur Batteries ◽  
Doped Graphene ◽  
Sulfur Battery ◽  
Areal Capacity ◽  
Lithium Sulfur

A sufficient areal capacity is necessary for achieving high-energy lithium sulfur battery, which requires high enough sulfur loading in cathode materials. Therefore, kinetically fast catalytic conversion of polysulfide intermediates is...

scholarly journals An approach to emerging optical and optoelectronic applications based on NiO micro- and nanostructures

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
María Taeño ◽  
David Maestre ◽  
Ana Cremades
Keyword(s):  
Gas Sensors ◽  
High Frequency ◽  
Future Research ◽  
Electrochromic Devices ◽  
Fuel Cell Electrodes ◽  
Magnetic Devices ◽  
Optical Microresonators ◽  
Optical Limiters ◽  
Recent Developments ◽  
Potential Applicability

Abstract Nickel oxide (NiO) is one of the very few p-type semiconducting oxides, the study of which is gaining increasing attention in recent years due to its potential applicability in many emerging fields of technological research. Actually, a growing number of scientific works focus on NiO-based electrochromic devices, high-frequency spintronics, fuel cell electrodes, supercapacitors, photocatalyst, chemical/gas sensors, or magnetic devices, among others. However, less has been done so far in the development of NiO-based optical devices, a field in which this versatile transition metal oxide still lags in performance despite its potential applicability. This review could contribute with novelty and new forefront insights on NiO micro and nanostructures with promising applicability in optical and optoelectronic devices. As some examples, NiO lighting devices, optical microresonators, waveguides, optical limiters, and neuromorphic applications are reviewed and analyzed in this work. These emerging functionalities, together with some other recent developments based on NiO micro and nanostructures, can open a new field of research based on this p-type material which still remains scarcely explored from an optical perspective, and would pave the way to future research and scientific advances.

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