scholarly journals Laser Synthesis of Iridium Nanospheres for Overall Water Splitting

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3028 ◽  
Author(s):  
Hai-Bin Wang ◽  
Jia-Qi Wang ◽  
Neli Mintcheva ◽  
Min Wang ◽  
Shuang Li ◽  
...  
Keyword(s):  
Water Splitting ◽  
Cell Voltage ◽  
Bifunctional Catalyst ◽  
Catalytic Performance ◽  
Dark Field ◽  
Atomic Steps ◽  
Overall Water Splitting ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Atom Level

Engineering surface structure of catalysts is an efficient way towards high catalytic performance. Here, we report on the synthesis of regular iridium nanospheres (Ir NSs), with abundant atomic steps prepared by a laser ablation technique. Atomic steps, consisting of one-atom level covering the surface of such Ir NSs, were observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The prepared Ir NSs exhibited remarkably enhanced activity both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic medium. As a bifunctional catalyst for overall water splitting, they achieved a cell voltage of 1.535 V @ 10 mA/cm2, which is much lower than that of Pt/C-Ir/C couple (1.630 V @ 10 mA/cm2).

Design of a new objective lens for an HB-501A STEM

1991 ◽  
Vol 49 ◽  
pp. 416-417
Author(s):  
Earl J. Kirkland ◽  
Robert J. Keyse
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Objective Lens ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
High Resolution Microscopy

An ultra-high resolution pole piece with a coefficient of spherical aberration Cs=0.7mm. was previously designed for a Vacuum Generators HB-501A Scanning Transmission Electron Microscope (STEM). This lens was used to produce bright field (BF) and annular dark field (ADF) images of (111) silicon with a lattice spacing of 1.92 Å. In this microscope the specimen must be loaded into the lens through the top bore (or exit bore, electrons traveling from the bottom to the top). Thus the top bore must be rather large to accommodate the specimen holder. Unfortunately, a large bore is not ideal for producing low aberrations. The old lens was thus highly asymmetrical, with an upper bore of 8.0mm. Even with this large upper bore it has not been possible to produce a tilting stage, which hampers high resolution microscopy.

Atomic resolution Z-contrast imaging of bulk crystal surfaces in Scanning Reflection Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 414-415
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
Electron Microscopy ◽  
Elastic Scattering ◽  
Dark Field ◽  
Contrast Imaging ◽  
Crystal Lattices ◽  
Small Probe ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Image Position ◽  
Z Contrast

The success of obtaining atomic-number-sensitive (Z-contrast) images in scanning transmission electron microscopy (STEM) has shown the feasibility of imaging composition changes at the atomic level. This type of image is formed by collecting the electrons scattered through large angles when a small probe scans across the specimen. The image contrast is determined by two scattering processes. One is the high angle elastic scattering from the nuclear sites,where ϕNe is the electron probe function centered at bp = (Xp, yp) after penetrating through the crystal; F denotes a Fourier transform operation; D is the detection function of the annular-dark-field (ADF) detector in reciprocal space u. The other process is thermal diffuse scattering (TDS), which is more important than the elastic contribution for specimens thicker than about 10 nm, and thus dominates the Z-contrast image. The TDS is an average “elastic” scattering of the electrons from crystal lattices of different thermal vibrational configurations,

STEM measurement of subcellular water distributions

1993 ◽  
Vol 51 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
S.Q. Sun ◽  
S-L. Shi ◽  
R.A. Buchanan ◽  
S.B. Andrews
Keyword(s):  
Water Content ◽  
Internal Standard ◽  
Dry Weight ◽  
Dry Mass ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Bulk Water ◽  
Inelastic Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

In situ formation of highly exposed NiPS3 nanosheets on nickel foam as an efficient 3D electrocatalyst for overall water splitting

2021 ◽  
Author(s):  
Liang Fang ◽  
Yanping Xie ◽  
Peiyin Guo ◽  
Jingpei Zhu ◽  
Shuhui Xiao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Nickel Foam ◽  
Chemical Vapor ◽  
Bifunctional Catalyst ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Overall Water Splitting ◽  
One Step ◽  
Transport Method

Vertical NiPS3 nanosheets in situ grown on conducting nickel foam were fabricated by a facile one-step chemical vapor transport method and used as an efficient bifunctional catalyst for overall water splitting.

Atomic-scale structural and compositional analyses of Ruddlesden-Popper planar faults in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics

2009 ◽  
Vol 24 (8) ◽  
pp. 2596-2604 ◽  
Author(s):  
Sašo Šturm ◽  
Makoto Shiojiri ◽  
Miran Čeh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Initial Stage ◽  
Final Microstructure ◽  
Scanning Transmission ◽  
The Matrix ◽  
Annular Dark Field

The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.

Pt Modified Ni-Mo-based Hydrate as Bifunctional Electrocatalysts for Overall Water Splitting

2021 ◽  
Author(s):  
Yayu Guan ◽  
Yuyu Liu
Keyword(s):  
Water Splitting ◽  
Catalytic Performance ◽  
Overall Water Splitting ◽  
Bifunctional Electrocatalysts ◽  
Excellent Catalytic Performance

Pt-modified Ni-Mo-based nanomaterials were prepared by a simple and effective method. The modified Ni-Mo-based materials exhibited excellent catalytic performance in KOH solution by adjusting the amount of Pt introduced. Due...

scholarly journals Exploring the Capability of HAADF-STEM Techniques to Characterize Graphene Distribution in Nanocomposites by Simulations

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
N. Baladés ◽  
D. L. Sales ◽  
M. Herrera ◽  
A. M. Raya ◽  
J. C. Hernández-Garrido ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Carbon Matrix ◽  
Reconstruction Algorithm ◽  
Dark Field ◽  
Graphene Layers ◽  
Transmission Electron ◽  
Dispersion Degree ◽  
Scanning Transmission ◽  
The Matrix ◽  
Annular Dark Field

This paper explores the capability of scanning transmission electron microscopy (STEM) techniques in determining the dispersion degree of graphene layers within the carbon matrix by using simulated high-angle annular dark-field (HAADF) images. Results ensure that unmarked graphene layers are only detectable if their orientation is parallel to the microscope beam. Additionally, gold-marked graphene layers allow evaluating the dispersion degree in structural composites. Moreover, electron tomography has been demonstrated to provide truthfully 3D distribution of the graphene sheets inside the matrix when an appropriate reconstruction algorithm and 2D projections including channelling effect are used.

STEM Analysis of Atom Location in (Cu, Au, Ni)6Sn5 Intermetallic Compounds

2018 ◽  
Vol 273 ◽  
pp. 95-100
Author(s):  
Wen Hui Yang ◽  
Tomokazu Yamamoto ◽  
Kazuhiro Nogita ◽  
Syo Matsumura
Keyword(s):  
Dark Field ◽  
Hexagonal Structure ◽  
Atomic Resolution ◽  
Chemical Mapping ◽  
Soldering Process ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Direct Alloying ◽  
Resolution Level ◽  
Evolution Of Microstructure

Cu6Sn5 is an important intermetallic compound in soldering and electronic packaging. It is formed at the interface between molten solder and substrate during the soldering process, and the evolution of microstructure and properties also occurs in service. Previous studies revealed that Au and Ni are stabilization alloying elements for hexagonal η-Cu6Sn5 intermetallic. For better understanding of stabilization mechanisms at atomic resolution level, in this work, we made an attempt atomic structure analysis on a stoichiometric (Cu, Au, Ni)6Sn5 intermetallic prepared by direct alloying. High-angle annular dark-field (HAADF) imaging and atomic-resolution chemical mapping were taken by the aberration-corrected (Cs-corrected) scanning transmission electron microscopy (STEM). It is found that Au and Ni doped Cu6Sn5 has hexagonal structure. The atom sites of Cu1 and Sn can be distinguished in atomic-resolution images after being observed from orientation [2110], which is also confirmed by atomic-resolution chemical mapping analysis. Importantly, atomic-resolution about distribution of alloying Au atom was directly observed, and Au atoms occupy the Cu1 sites in η-Cu6Sn5.

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