High Current Density and Longtime Stable Field Electron Transfer from Large-Area Densely Arrayed Graphene Nanosheet–Carbon Nanotube Hybrids

Carbon nanotube (CNT) has a great tolerance to high current density which is a cause of electromigration (EM). Therefore, CNT is expected to use as the materials of nanoscale components of electronic devices. The damage mechanisms of CNT are regarded as the effects of oxidation by Joule heating and/or the EM by high-density electron flows. In this study, we investigated the damage mechanism of CNT structures used as nano-component of electronic devices. An EM acceleration testing system was designed using the CNT structures collected at the gap of thin-film electrodes. The EM tests were conducted under the several kinds of current density conditions and the surrounding environments. An indicator of lifetime was determined by voltage measurements during the acceleration tests and their fracture phenomena were evaluated by means of microscopic observations. As the results, the amounts of lifetime of CNT were longer in the lower oxygen concentrations than in the air condition. In the microscopic studies, it was confirmed that the local evaporation of carbon atoms due to oxidation appeared at the cathode side of the CNT structures under low current density, and the center area of CNT under high current density. Both types of damage morphologies induced by oxidation and EM were observed at the damaged CNT. The results showed the dominant damage mechanism alternated between oxidation and EM depending on current density under oxygen rich conditions.

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Vertically aligned carbon nanotube electrodes for high current density operating proton exchange membrane fuel cells

Journal of Power Sources ◽

10.1016/j.jpowsour.2013.11.073 ◽

2014 ◽

Vol 253 ◽

pp. 104-113 ◽

Cited By ~ 58

Author(s):

Shigeaki Murata ◽

Masahiro Imanishi ◽

Shigeki Hasegawa ◽

Ryoichi Namba

Keyword(s):

Fuel Cells ◽

Carbon Nanotube ◽

Current Density ◽

Proton Exchange Membrane ◽

High Current Density ◽

Proton Exchange ◽

High Current ◽

Vertically Aligned ◽

Exchange Membrane

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Unexpected Genomic Features of High Current Density-Producing Geobacter sulfurreducens strain YM18

FEMS Microbiology Letters ◽

10.1093/femsle/fnab119 ◽

2021 ◽

Author(s):

Takashi Fujikawa ◽

Yoshitoshi Ogura ◽

Koki Ishigami ◽

Yoshihiro Kawano ◽

Miyuki Nagamine ◽

...

Keyword(s):

Electron Transfer ◽

Current Density ◽

Iron Reduction ◽

High Current Density ◽

Model Organism ◽

Geobacter Sulfurreducens ◽

Extracellular Electron Transfer ◽

High Current ◽

Current Production ◽

Current Densities

Abstract Geobacter sulfurreducens produces high current densities and it has been used as a model organism for extracellular electron transfer studies. Nine G. sulfurreducens strains were isolated from biofilms formed on an anode poised at –0.2 V (vs. SHE) in a bioelectrochemical system in which river sediment was used as an inoculum. The maximum current density of an isolate, strain YM18 (9.29 A/m2), was higher than that of the strains PCA (5.72 A/m2), the type strain of G. sulfurreducens, and comparable to strain KN400 (8.38 A/m2), which is another high current producing strain of G. sulfurreducens. Genomic comparison of strains PCA, KN400, and YM18 revealed that omcB, xapD, spc, and ompJ, which are known to be important genes for iron reduction and current production in PCA, were not present in YM18. In the PCA and KN400 genomes, two and one region (s) encoding CRISPR/Cas systems were identified, respectively, but they were missing in the YM18 genome. These results indicate that there is genetic variation in the key components involved in extracellular electron transfer among G. sulfurreducens strains.

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Philips electron microscopes: Applications trends—design advances

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129516 ◽

1992 ◽

Vol 50 (2) ◽

pp. 976-977

Author(s):

M.N. Thompson

Keyword(s):

Current Density ◽

High Current Density ◽

Total Current ◽

High Current ◽

Large Area ◽

Small Probe ◽

Field Emitters ◽

Chemical Resolution ◽

Electron Microscopes ◽

Reasonable Choice

Application trends in the 1990's will continue to be driven by the pursuit of materials characterisation to higher levels of structural and chemical resolution. Due to the information-limit and current-density limitations of LaB6 sources, further advancements will require better electron guns. The choice of guns includes Cold, Thermally-assisted Cold and Schottky Field Emitters. For SEM and STEM the Cold Field Emitter is a reasonable choice, because the primary criterion for small-probe techniques is current density. This logic doesn't apply to TEMs, which require both high current density for small probes and high total current for large-area illumination at various TEM magnification levels. Table 1 compares Schottky and Cold Field emitters in different applications and microscope construction. In view of its performance (Figs. 1 and 2), the Field Emission Gun is expected to have a major impact on TEM in the 1990's.

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