Molecular Functionalization of Graphite Surfaces: Basal Plane versus Step Edge Electrochemical Activity

AbstractThe reactions of O2, H2O, CO2, NO2, NO, and N2O with single crystal graphite between 400 and 700°C have been studied by STM to obtain quantitative kinetics by measuring the number and size of monolayer pits on the basal plane versus temperature and time. At low temperature the reaction initiates exclusively from the point defects on the basal plane to form monolayer pits. The shape of the monolayer pits vary from nearly triangular to hexagonal to circular depending on the rate of the reaction and the reacting gases. The sizes of the monolayer pits grow linearly with reacting time. The monolayer reaction rates follow the order of RNO2 > RN2O > RNO > RO2 > RH2O > RCO2. The activation energies for reactions with O2, H2O, NO2, NO, and N2O, are determined to be 127, 205, 60, 89, and 74 kJ/mol respectively.Carbon deposition from hydrocarbons onto surfaces of single crystal graphite has been examined to study the fundamental steps of chemical vapor deposition. Uniform monolayer pits on graphite surface were first produced by reactive etching of freshly cleaved single crystal of graphite in oxygen and carbon was then made to deposit exclusively on these defects in the basal plane. Carbon vapor deposition forms unique structures around the monolayer steps. By measuring the sizes of structures on steps in various gases versus temperature and pressure, the kinetics of hydrocarbon decomposition and the role of surface diffusion can be determined.

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Unravelling the electrocatalytic activity of bismuth nanosheets towards carbon dioxide reduction: edge plane versus basal plane

Applied Catalysis B Environmental ◽

10.1016/j.apcatb.2021.120693 ◽

2021 ◽

pp. 120693

Author(s):

Dan Wang ◽

Kuan Chang ◽

Yaning Zhang ◽

Yanying Wang ◽

Qixin Liu ◽

...

Keyword(s):

Carbon Dioxide ◽

Basal Plane ◽

Electrocatalytic Activity ◽

Carbon Dioxide Reduction ◽

Plane Versus

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Increasing the electrochemical activity of basal plane sites in porous 3D edge rich MoS2 thin films for the hydrogen evolution reaction

Materials Today Energy ◽

10.1016/j.mtener.2019.05.002 ◽

2019 ◽

Vol 13 ◽

pp. 134-144 ◽

Cited By ~ 9

Author(s):

Sha Li ◽

Si Zhou ◽

Xiaochen Wang ◽

Peng Tang ◽

Mauro Pasta ◽

...

Keyword(s):

Thin Films ◽

Hydrogen Evolution ◽

Hydrogen Evolution Reaction ◽

Basal Plane ◽

Electrochemical Activity

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Reproducible, stable and fast electrochemical activity from easy to make graphene on copper electrodes

Physical Chemistry Chemical Physics ◽

10.1039/c5cp04070a ◽

2015 ◽

Vol 17 (44) ◽

pp. 29628-29636 ◽

Cited By ~ 14

Author(s):

Concha Bosch-Navarro ◽

Zachary P. L. Laker ◽

Jonathan P. Rourke ◽

Neil R. Wilson

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Basal Plane ◽

Chemical Vapor ◽

Electrochemical Activity ◽

Simple Route ◽

Copper Electrodes ◽

Electrochemical Response ◽

Grown Graphene ◽

Electrochemical Electrode

Chemical vapor deposition grown graphene on copper is a fast, robust and easy to make electrochemical electrode. The electrochemical response is independent of the amount of basal-plane/edge-plane of graphene, and fully covered samples show no electrode fouling, giving a simple route to study graphene based electrodes.

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Observations of the Thermal Decomposition of Brucite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101980 ◽

1968 ◽

Vol 26 ◽

pp. 446-447

Author(s):

P. L. Burnett ◽

W. R. Mitchell ◽

C. L. Houck

Keyword(s):

Thermal Decomposition ◽

Magnesium Oxide ◽

Basal Plane ◽

Magnesium Ions ◽

A Value ◽

Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

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The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171742 ◽

1994 ◽

Vol 52 ◽

pp. 802-803

Author(s):

Y. Feng ◽

X. Y. Cai ◽

R. J. Kelley ◽

D. C. Larbalestier

Keyword(s):

Single Crystals ◽

Oxygen Content ◽

Basal Plane ◽

Flux Pinning ◽

Pinning Centers ◽

Before And After ◽

Anomalous Peak ◽

Basal Plane Dislocation ◽

The Stability ◽

Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

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Microstructure and Physical Properties of Clay-Polymer Composites

MRS Proceedings ◽

10.1557/proc-628-cc11.14 ◽

2000 ◽

Vol 628 ◽

Author(s):

T.N. Blanton ◽

D. Majumdar ◽

S.M. Melpolder

Keyword(s):

Composite Materials ◽

Physical Properties ◽

Polymer Composites ◽

Basal Plane ◽

X Ray Diffraction ◽

X Ray ◽

Layered Clay

ABSTRACTClay-polymer nanoparticulate composite materials are evaluated by the X-ray diffraction technique. The basal plane spacing provided information about the degree of intercalation and exfoliation of the 2: 1 layered clay structure. Both intercalation and exfoliation are controlled by the identity of the polymer and the clay:polymer ratio.

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