scholarly journals Structural Defects of Graphene Oxidation Reduction and Its High-Efficiency Structural Reforming Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Junwei An ◽  
Chen Wen ◽  
Chuping Chen ◽  
Xiaolin Qiu
Keyword(s):  
Carrier Transport ◽  
High Efficiency ◽  
Great Influence ◽  
Impurity Content ◽  
Reduction Reaction ◽  
Structural Defects ◽  
Oxidation Reduction ◽  
High Carrier ◽  
Graphene Oxidation ◽  
Battery Industry

The Hummers’ method is used to prepare graphene oxide and graphene powder, and the obtained powder material contains a large amount of oxygen-containing groups. Due to the effect of strong oxidants, there are many defects on the graphene body. Although a large number of oxygen-containing groups are reduced by the reduction reaction, the defects of the graphene body are numerous, which has a great influence on the conductivity of graphene and also limits the high carrier transport capability and application of graphene itself. Using industrial means, the graphene powder is highly reduced, and the ultrathin graphene powder is obtained, the graphene powder has extremely low impurity content, and the defects are substantially completely reduced. Then, these lay the foundation for its application in the battery industry.

scholarly journals Recent Studies on Multifunctional Electrocatalysts for Fuel Cell by Various Nanomaterials

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 621 ◽  
Author(s):  
Sanha Jang ◽  
Kyeongmin Moon ◽  
Youchang Park ◽  
Sujung Park ◽  
Kang Hyun Park
Keyword(s):  
Fuel Cell ◽  
Environmental Factors ◽  
Water Splitting ◽  
Hydrogen Evolution Reaction ◽  
Oxidation Reaction ◽  
High Efficiency ◽  
Electrochemical Reaction ◽  
Reduction Reaction ◽  
Structural Defects ◽  
Catalytic Applications

Based on nanotechnology, nanocomposites are synthesized using nanoparticles (NP), which have some advantages in terms of multifunctional, economic, and environmental factors. In this review, we discuss the inorganic applications as well as catalytic applications of NPs. Recently, structural defects, heteroatomic doping, and heterostructures of such efficient ideal catalysts and their application as multifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in water splitting. It has been verified that the catalysts used in oxygen reduction reaction and OER can be used effectively in metal/air batteries. Moreover, it has been reported that high-efficiency catalysts are required to implement urea oxidation reaction (UOR), which involves a six-electron reaction, as an electrochemical reaction. We expect that this review can be applied to sustainable and diverse electrochemistry fields.

scholarly journals A Review of Hydrogen Purification Technologies for Fuel Cell Vehicles

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Zhemin Du ◽  
Congmin Liu ◽  
Junxiang Zhai ◽  
Xiuying Guo ◽  
Yalin Xiong ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Emission ◽  
High Efficiency ◽  
Impurity Content ◽  
Fuel Cell Vehicle ◽  
Research Progress ◽  
Hydrogen Purification ◽  
Fuel Cell Vehicles ◽  
Low Carbon

Nowadays, we face a series of global challenges, including the growing depletion of fossil energy, environmental pollution, and global warming. The replacement of coal, petroleum, and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2) energy is considered the ultimate energy in the 21st century because of its diverse sources, cleanliness, low carbon emission, flexibility, and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission, they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops, H2 fuel supply, especially H2 quality, attracts increasing attention. Compared with H2 for industrial use, the H2 purity requirements for fuel cells are not high. Still, the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore, we analyze the causes and developing trends for the changes in these standards in detail. On the other hand, according to characteristics of H2 for fuel cell vehicles, standard H2 purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed.

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

2020 ◽  
pp. 095441002096645
Author(s):  
Jie Gao ◽  
Chunde Tao ◽  
Dongchen Huo ◽  
Guojie Wang
Keyword(s):  
Performance Improvement ◽  
High Efficiency ◽  
Three Dimensional ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axial Turbine ◽  
Flow Interactions ◽  
And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

scholarly journals Quasi-graphitic carbon shell-induced Cu confinement promotes electrocatalytic CO2 reduction toward C2+ products

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ji-Yong Kim ◽  
Deokgi Hong ◽  
Jae-Chan Lee ◽  
Hyoung Gyun Kim ◽  
Sungwoo Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Co2 Reduction ◽  
Value Added ◽  
Material Design ◽  
Catalyst System ◽  
Critical Issue ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Design Strategies ◽  
Faradaic Efficiency

AbstractFor steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

Structural Design and Forming Method of Single-Curved Surface Structure Based on Miura-Origami

2016 ◽  
Author(s):  
Hairui Wang ◽  
Chunfang Guo ◽  
Yujie Li ◽  
Yahua Liu ◽  
Minjie Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Structural Design ◽  
High Efficiency ◽  
Circular Tube ◽  
Great Influence ◽  
Curved Surface ◽  
Structural Performance ◽  
Forming Process ◽  
Structural Support ◽  
Vacuum Forming

With the advantage of high adaptability, Miura-origami structure with curvature shows various engineering applications such as a sandwich between two stiff facings with curvature requirements and structural support to form a circular tube. In this research, a forming method of polymer circular tube with single-curved surface origami expressed by five parameters was established and its corresponding theory was solved considering forming rationality in actual manufacturing. The components of circular tube were fabricated by the vacuum forming process and then spliced together. We conducted numerical simulation to analyze the structural performance of the tube with five parameters and shown that these parameters have a great influence on energy absorbed performance. Finally, a male mold of a part with Arc Miura-origami structure was designed and fabricated. The parts with Arc Miura-origami were manufactured using vacuum forming process and then spliced and bonded together into a two-layer tube. This research may provide a method to design and fabricate Miura-origami structure with high efficiency and quality.

Pseudomonas aeruginosa transition from environmental generalist to human pathogen

2021 ◽  
Vol 13 (1) ◽  
pp. 11
Author(s):  
Gabriela Vasco ◽  
Gabriel Trueba
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Human Body ◽  
Biofilm Formation ◽  
Reduction Reaction ◽  
Human Pathogen ◽  
Opportunistic Bacteria ◽  
Oxidation Reduction ◽  
Mammalian Tissues ◽  
Oxidation Reduction Reaction ◽  
Source Sink

Opportunistic bacteria Pseudomonas aeruginosa is one of the major concerns as an etiological agent of nosocomial infections in humans. Many virulence factors used to colonize the human body are the same as those used by P. aeruginosa to thrive in the environment such as membrane transport, biofilm formation, oxidation/reduction reaction, among others. P. aeruginosa origin is mainly from the environment, the adaptation to mammalian tissues may follow a source-sink evolution model; the environment is the source of many lineages, some of them capable of adaptation to the human body. Some lineages may adapt to humans and go through reductive evolution in which some genes are lost.  The understanding of this process may be critical to implement better methods to control outbreaks in hospitals.

Improved Mobility and Bias Stability of Thin Film Transistors Using the Double-Layer a-InGaZnO/a-InGaZnO:N Channel

2016 ◽  
Vol 16 (4) ◽  
pp. 3659-3663
Author(s):  
H Yu ◽  
L Zhang ◽  
X. H Li ◽  
H. Y Xu ◽  
Y. C Liu
Keyword(s):  
Thin Film ◽  
Double Layer ◽  
Thin Film Transistors ◽  
Carrier Transport ◽  
Single Layer ◽  
Channel Structure ◽  
Gate Insulator ◽  
Large Area ◽  
Threshold Voltage Shift ◽  
High Carrier

The amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) were demonstrated based on a double-layer channel structure, where the channel is composed of an ultrathin nitrogenated a-IGZO (a-IGZO:N) layer and an undoped a-IGZO layer. The double-layer channel device showed higher saturation mobility and lower threshold-voltage shift (5.74 cm2/Vs, 2.6 V) compared to its single-layer counterpart (0.17 cm2/Vs, 7.23 V). The improvement can be attributed to three aspects: (1) improved carrier transport properties of the channel by the a-IGZO:N layer with high carrier mobility and the a-IGZO layer with high carrier concentration, (2) reduced interfacial trap density between the active channel and the gate insulator, and (3) higher surface flatness of the double-layer channel. Our study reveals key insights into double-layer channel, involving selecting more suitable electrical property for back-channel layer and more suitable interface modification for active layer. Meanwhile, room temperature fabrication amorphous TFTs offer certain advantages on better flexibility and higher uniformity over a large area.

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