scholarly journals Functionalized and Platinum-Decorated Multi-Layer Oxidized Graphene as a Proton, and Electron Conducting Separator in Solid Acid Fuel Cells

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 947
Author(s):  
Mhamad Hamza Hatahet ◽  
Maximilian Wagner ◽  
Andrea Prager ◽  
Ulrike Helmstedt ◽  
Bernd Abel
Keyword(s):  
Solid Acid ◽  
Electrochemical Impedance ◽  
Platinum Catalyst ◽  
State Of The Art ◽  
Graphene Film ◽  
Stable Operation ◽  
Fuel Cell Electrodes ◽  
Layer Graphene ◽  
Electrode Resistance ◽  
Platinum Loading

In the present article, electrodes containing a composite of platinum on top of a plasma-oxidized multi-layer graphene film are investigated as model electrodes that combine an exceptional high platinum utilization with high electrode stability. Graphene is thereby acting as a separator between the phosphate-based electrolyte and the platinum catalyst. Electrochemical impedance measurements in humidified hydrogen at 240 °C show area-normalized electrode resistance of 0.06 Ω·cm−2 for a platinum loading of ∼60 µgPt·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. The presented platinum decorated graphene electrodes enable stable operation over 60 h with a non-optimized degradation rate of 0.15% h−1, whereas electrodes with a similar design but without the graphene as separator are prone to a very fast degradation. The presented results propose an efficient way to stabilize solid acid fuel cell electrodes and provide valuable insights about the degradation processes which are essential for further electrode optimization.

Fast Degradation for High Activity: Oxygen- and Nitrogen-Functionalised Carbon Nanotubes in Solid-Acid Fuel-Cell Electrodes

ChemSusChem ◽  
2016 ◽  
Vol 9 (23) ◽  
pp. 3298-3306 ◽  
Author(s):  
Olga Naumov ◽  
Sergej Naumov ◽  
Roman Flyunt ◽  
Bernd Abel ◽  
Aron Varga
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cell ◽  
High Activity ◽  
Solid Acid ◽  
Fuel Cell Electrodes

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

ASSESSMENT OF MULTALL AS CFD CODE FOR THE ANALYSIS OF TUBE-AXIAL FANS

2021 ◽  
pp. 1-12
Author(s):  
Piero Danieli ◽  
Massimo Masi ◽  
Giovanni Delibra ◽  
Alessandro Corsini ◽  
Andrea Lazzaretto
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Velocity Distribution ◽  
High Speed ◽  
State Of The Art ◽  
Stable Operation ◽  
Pressure Curve ◽  
Analysis Tool ◽  
Low Speed ◽  
Axial Fans

Abstract This work deals with the application of the open source CFD code MULTALL to the analysis of tube-axial-fans. The code has been widely validated in the literature for high-speed turbomachine flows but not applied yet to low speed tutbomachines. The aim of this work is to assess the degree of reliability of MULTALL as a tool for simulating the internal flow in industrial axial-flow fan rotors. To this end, the predictions of the steady-state air flow field in the annular sector of a 315 mm tube-axial fan obtained by MULTALL 18.3 are compared with those obtained by two state-of-the-art CFD codes and experimental data of the global aerodynamic performance of the fan and the pitch-wise averaged velocity distribution downstream of the rotor. All the steady-state RANS calculations were performed on either fully structured hexahedron or hexa-dominant grids using classical formulations of algebraic turbulence models. The pressure curve and the trend of the aeraulic efficiency in the stable operation range of the fan predicted by MULTALL show very good agreement with both the experimental data and the other CFD results. Although the estimation of the fan efficiency predicted by MULTALL can be noticeably improved by the more sophisticated state-of-the-art CFD codes, the analysis of the velocity distribution at the rotor exit supports the use of MULTALL as a reliable CFD analysis tool for designers of low-speed axial fans.

Few-layer graphene film fabricated by femtosecond pulse laser deposition without catalytic layers

2015 ◽  
Vol 13 (2) ◽  
pp. 021601-21604 ◽  
Author(s):  
Xiangming Dong Xiangming Dong ◽  
Shibing Liu Shibing Liu ◽  
Haiying Song Haiying Song ◽  
Peng Gu Peng Gu ◽  
Xiaoli Li Xiaoli Li
Keyword(s):  
Pulse Laser Deposition ◽  
Pulse Laser ◽  
Femtosecond Pulse ◽  
Graphene Film ◽  
Laser Deposition ◽  
Femtosecond Pulse Laser ◽  
Layer Graphene ◽  
Few Layer Graphene ◽  
Catalytic Layers

scholarly journals Chemical Vapour Deposition of Graphene for Durable Anticorrosive Coating on Copper

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2511
Author(s):  
Dali Ji ◽  
Xinyue Wen ◽  
Tobias Foller ◽  
Yi You ◽  
Fei Wang ◽  
...  
Keyword(s):  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Electrochemical Impedance ◽  
Pure Copper ◽  
Chemical Vapour ◽  
Source Surface ◽  
Layer Graphene ◽  
Chemical Inertness ◽  
Grown Graphene ◽  
One Year

Due to the excellent chemical inertness, graphene can be used as an anti-corrosive coating to protect metal surfaces. Here, we report the growth of graphene by using a chemical vapour deposition (CVD) process with ethanol as a carbon source. Surface and structural characterisations of CVD grown films suggest the formation of double-layer graphene. Electrochemical impedance spectroscopy has been used to study the anticorrosion behaviour of the CVD grown graphene layer. The observed corrosion rate of 8.08 × 10−14 m/s for graphene-coated copper is 24 times lower than the value for pure copper which shows the potential of graphene as the anticorrosive layer. Furthermore, we observed no significant changes in anticorrosive behaviour of the graphene coated copper samples stored in ambient environment for more than one year.

Layer-by-Layer Doping of Few-Layer Graphene Film

ACS Nano ◽  
2010 ◽  
Vol 4 (8) ◽  
pp. 4595-4600 ◽  
Author(s):  
Fethullah Güneş ◽  
Hyeon-Jin Shin ◽  
Chandan Biswas ◽  
Gang Hee Han ◽  
Eun Sung Kim ◽  
...  
Keyword(s):  
Graphene Film ◽  
Layer By Layer ◽  
Layer Graphene ◽  
Few Layer Graphene

Highly sensitive wearable sensor based on a flexible multi-layer graphene film antenna

2018 ◽  
Vol 63 (9) ◽  
pp. 574-579 ◽  
Author(s):  
Danli Tang ◽  
Qianlong Wang ◽  
Zhe Wang ◽  
Quantao Liu ◽  
Bin Zhang ◽  
...  
Keyword(s):  
Graphene Film ◽  
Wearable Sensor ◽  
Layer Graphene ◽  
Highly Sensitive
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