Research interest in low dimensional materials has expanded immensely in the last decade. The fascinating properties of nanotubes, graphene and transition metal dichalcogenides (TMDCs) has pushed this research toward applications in composites, (opto)‐electronics and photovoltaics. Seeing and understanding the physical and chemical structure of these nanostructures is a vital aspect of this growing research area. Using rotational tomography on low dimensional TMDCs, we reveal additional points of view that are not routine in transmission electron microscopy (TEM). Bright field TEM highlights the non‐uniformity of tungsten disulphide (WS 2 ) nanotube tips, as well as revealing structural deformities in the nanotubes as a whole. Complimentary to this, we present high‐angle annular dark field (HAADF) scanning TEM tomography, which provides clearer structural interpretation through fewer Bragg scattering events being detected. 2D nanosheets are also characterised via high resolution TEM tomography, allowing for a three dimensional view of a 2D object. As the sample is rotated, further lattice and thickness information is acquired. Having these complimentary tomographic methods available for nanomaterial characterisation will help to improve the accuracy of interpretation and results. Often, 2D TEM images lead to assumptions about the nature of these materials. Tomography at high resolution will reveal more information on the shape and structure of the studied nanomaterials (e.g., ripples) in 3D.
Abstract Formic acid derived from biomass is known to be used for hydrogen production over Pd catalysts. The effects of preparation variables, structure of the carbon support, surface functional composition on the state of Pd, and catalytic properties of the samples in the vapor‐phase decomposition of formic acid were studied. In all catalysts derived from Pd acetate, metal particles visible by conventional TEM had similar sizes, but the adsorption capacity towards CO responded strongly to N‐doping of the carbon surface. Moreover, a decrease in the CO/Pd values was accompanied by a significant increase in the reaction rate. Taking account of X‐ray photoelectron spectroscopy (XPS) and atomic resolution high‐angle annular dark‐field scanning transmission electron microscopy (HAADF/STEM) data, the trends observed were assigned to a larger fraction of single electron‐deficient Pd atoms in the N‐doped samples, which do not adsorb CO but interact with formic acid to produce hydrogen. This was confirmed by extended DFT studies. The obtained results are valuable for the development of Pd catalysts on carbon supports for different processes.
If coated conductors are to be used in large-scale ac applications such as motors and generators, energy losses must be minimised. Hysteretic ac losses can be reduced by dividing the coated conductor into filaments. In this study, a new method for producing filamentary coated conductors is presented. An electrical spark discharge was used to selectively degrade regions of superconducting tape. The robust, noncontact and scalable method was used to striate tapes into four filaments. The filamentary samples had lower ac losses than nonstriated tapes with less than a 7% reduction in current carrying capacity.
Data supporting the publication including: Hall probe magnetometry, scanning electron microscopy, critical current measurements and AC loss measurement raw data.
Herein, we report the synthesis and complete structural characterization of curved CuIn1–xGax(S1–ySey)2 (x = y = 0.5) nanocrystals, which adopt a two-dimensional (2D) nanoplate morphology and crystallize in the hexagonal wurtzite phase. A detailed transmission electron microscopy (TEM) analysis reveals that the 2D nanoplates are predominately [001]-oriented and exhibit a unique bend contour pattern, because of curvature on the (001) basal plane. The contrast behavior of bend contours in this system is further supported through specimen-tilting experiments inside TEM, in combination with dark-field imaging in both TEM and scanning TEM modes. This bending is believed to originate from the proximity effect of the top and bottom (001) surfaces.
Boron nitride nanotubes (BNNTs) have unique physical properties, of value in biomedical applications; however, their dispersion and functionalization represent a critical challenge in their successful employment as biomaterials. In the present study, we report a process for the efficient disentanglement of BNNTs via a dual surfactant/polydopamine (PD) process. High-resolution transmission electron microscopy (HR-TEM) indicated that individual BNNTs become coated with a uniform PD nanocoating, which significantly enhanced dispersion of BNNTs in aqueous solutions. Furthermore, the cytocompatibility of PD-coated BNNTs was assessed in vitro with cultured human osteoblasts (HOBs) at concentrations of 1, 10, and 30 μg/mL and over three time-points (24, 48, and 72 h). In this study it was demonstrated that PD-functionalized BNNTs become individually localized within the cytoplasm by endosomal escape and that concentrations of up to 30 μg/mL of PD-BNNTs were cytocompatible in HOBs cells following 72 h of exposure.
'/%3e%3cpath d='M200 752.362h200v300H200z' style='fill:%23fff;fill-opacity:1;stroke:none' transform='translate(0 -752.362)'/%3e%3cpath d='M400 752.362h200v300H400z' style='fill:%23ff883e;fill-opacity:1;stroke:none' transform='translate(0 -752.362)'/%3e%3c/svg%3e)
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
