scholarly journals Acetylene hydrogenation over structured Au–Pd catalysts

2016 ◽  
Vol 188 ◽  
pp. 499-523 ◽  
Author(s):  
Alan J. McCue ◽  
Richard T. Baker ◽  
James A. Anderson
Keyword(s):  
Shell Morphology ◽  
Shell Structures ◽  
Core Shell ◽  
Shell Layer ◽  
Pd Catalysts ◽  
Acetylene Hydrogenation ◽  
The Core ◽  
Selective Hydrogenation Of Acetylene ◽  
Core Shell Structure ◽  
Improved Performance

AuPd nanoparticles were prepared following a methodology designed to produce core–shell structures (an Au core and a Pd shell). Characterisation suggested that slow addition of the shell metal favoured deposition onto the pre-formed core, whereas more rapid addition favoured the formation of a monometallic Pd phase in addition to some nanoparticles with the core–shell morphology. When used for the selective hydrogenation of acetylene, samples that possessed monometallic Pd particles favoured over-hydrogenation to form ethane. A sample prepared by the slow addition of a small amount of Pd resulted in the formation of a core–shell structure but with an incomplete Pd shell layer. This material exhibited a completely different product selectivity with ethylene and oligomers forming as the major products as opposed to ethane. The improved performance was thought to be as a result of the absence of Pd particles, which are capable of forming a Pd-hydride phase, with enhanced oligomer selectivity associated with reaction on uncovered Au atoms.

scholarly journals A SERS Study of Charge Transfer Process in Au Nanorod–MBA@Cu2O Assemblies: Effect of Length to Diameter Ratio of Au Nanorods

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 867
Author(s):  
Lin Guo ◽  
Zhu Mao ◽  
Sila Jin ◽  
Lin Zhu ◽  
Junqi Zhao ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Shell Structure ◽  
Shell Structures ◽  
Core Shell ◽  
Absorption Bands ◽  
Au Nanorods ◽  
The Core ◽  
Band Position ◽  
Surface Enhanced Raman ◽  
Core Shell Structure

Surface-enhanced Raman scattering (SERS) is a powerful tool in charge transfer (CT) process research. By analyzing the relative intensity of the characteristic bands in the bridging molecules, one can obtain detailed information about the CT between two materials. Herein, we synthesized a series of Au nanorods (NRs) with different length-to-diameter ratios (L/Ds) and used these Au NRs to prepare a series of core–shell structures with the same Cu2O thicknesses to form Au NR–4-mercaptobenzoic acid (MBA)@Cu2O core–shell structures. Surface plasmon resonance (SPR) absorption bands were adjusted by tuning the L/Ds of Au NR cores in these assemblies. SERS spectra of the core-shell structure were obtained under 633 and 785 nm laser excitations, and on the basis of the differences in the relative band strengths of these SERS spectra detected with the as-synthesized assemblies, we calculated the CT degree of the core–shell structure. We explored whether the Cu2O conduction band and valence band position and the SPR absorption band position together affect the CT process in the core–shell structure. In this work, we found that the specific surface area of the Au NRs could influence the CT process in Au NR–MBA@Cu2O core–shell structures, which has rarely been discussed before.

A review of electrode materials based on core–shell nanostructures for electrochemical supercapacitors

2019 ◽  
Vol 7 (8) ◽  
pp. 3516-3530 ◽  
Author(s):  
Kuo-Chuan Ho ◽  
Lu-Yin Lin
Keyword(s):  
Electrode Materials ◽  
Review Article ◽  
Shell Structures ◽  
Core Shell ◽  
Electrochemical Supercapacitors ◽  
Active Materials ◽  
The Core ◽  
The Past ◽  
Shell Nanostructures ◽  
Core Shell Structure

This review article outlines the most commonly used methods for making the core/shell structures as the active materials for supercapacitors over the past decade (2007–2018), and points out the most efficient combination of the material categories and morphologies for the core/shell structure.

Formation of Core–Shell Structures in Emulsion Electrospun Fibres: A Comparative Study

2014 ◽  
Vol 67 (10) ◽  
pp. 1403 ◽  
Author(s):  
Chong Wang ◽  
Min Wang
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Shell Structure ◽  
Sodium Dodecyl ◽  
Water Phase ◽  
Shell Structures ◽  
Ionic Surfactant ◽  
Core Shell ◽  
The Core ◽  
Core Shell Structure ◽  
Span 80

Electrospinning has attracted great attention in recent years from different industries including biomedical engineering. Owing to the relative ease of fabricating ultrafine fibres with core–shell structures, emulsion electrospinning has been investigated intensively for making nanofibrous delivery vehicles for local and sustained release of bioactive or therapeutic substances, especially biomolecules such as growth factors. In preparing emulsions for electrospinning, different surfactants, ionic or non-ionic, can be used, which may subsequently influence the evolution of the core–shell structure in the electrospun emulsion jet or fibre. In this investigation, emulsions consisting of deionized water or phosphate buffer saline as the water phase, a poly(lactic-co-glycolic acid) solution as the oil phase and Span 80 (a non-ionic surfactant) or sodium dodecyl sulfate (an ionic surfactant) were electrospun into fibres for studying the core–shell structure and its evolution in emulsion electrospun fibres. Different microscopies were employed to study the morphological changes of the water phase in fibre samples collected at different locations along the jet (or fibre) trajectory during emulsion electrospinning. It was found that the evolution of the fibre core–shell structure was significantly different when different surfactants were used. If Span 80 was the surfactant, the water phase within the thick emulsion jet (or fibre) close to the Taylor cone existed in a discrete state whereas in ultrafine fibres collected beyond a certain distance from the Taylor cone, a mostly continuous water-phase core was observed. If sodium dodecyl sulfate was the surfactant, the core–shell structure in the thick jet (or fibre) was irregular but relatively continuous. A single core core–shell structure was eventually developed in ultrafine fibres. The core–shell structure in electrospun fibres and its evolution were also affected by the emulsion composition (e.g. polymer solution concentration, water-phase volume, and ion addition in the water phase).

Construction of MOFs-Shell Porous Materials and Performance Study in Selective Adsorption and Separation of Benzene Pollutants

2021 ◽  
Author(s):  
Yu Qiao ◽  
Na Lv ◽  
Dong Li ◽  
Hongji Li ◽  
Xiangxin Xue ◽  
...  
Keyword(s):  
Porous Materials ◽  
Shell Structure ◽  
Selective Adsorption ◽  
Core Shell ◽  
Architecture Design ◽  
Performance Study ◽  
The Core ◽  
Core Shell Structure ◽  
And Performance ◽  
Sacrificial Agent

Metastable Cu2O is an attractive material for the architecture design of integrated nanomaterials. In this context, Cu2O was used as the sacrificial agent to form the core-shell structure of Cu2O@HKUST-1...

Preparation of polyacrylamide microspheres with core–shell structure via surface-initiated atom transfer radical polymerization

RSC Advances ◽  
2016 ◽  
Vol 6 (94) ◽  
pp. 91463-91467 ◽  
Author(s):  
Peng Zhang ◽  
Shixun Bai ◽  
Shilan Chen ◽  
Dandan Li ◽  
Zhenfu Jia ◽  
...  
Keyword(s):  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Shell Structure ◽  
Core Shell ◽  
Atom Transfer ◽  
The Core ◽  
Core Shell Structure

Well defined core–shell microspheres were prepared by surface-initiated atom transfer radical polymerization with pre-crosslinked polyacrylamide as the core and non-crosslinked polyacrylamide as the shell.

Core–shell stability of nanoparticles plays an important role for overcoming the intestinal mucus and epithelium barrier

2016 ◽  
Vol 4 (35) ◽  
pp. 5831-5841 ◽  
Author(s):  
Min Liu ◽  
Lei Wu ◽  
Xi Zhu ◽  
Wei Shan ◽  
Lian Li ◽  
...  
Keyword(s):  
Shell Structure ◽  
Core Shell ◽  
The Core ◽  
Shell Stability ◽  
Intestinal Mucus ◽  
Core Shell Structure ◽  
The Stability

The stability of the core–shell structure plays an important role in the nanoparticles ability to overcome both the mucus and epithelium absorption barrier.

Characterization of Fe3O4@CS@NMDP magnetic nanoparticles with core–shell structure prepared by chemical cross-linking method

2017 ◽  
Vol 10 (05) ◽  
pp. 1750056 ◽  
Author(s):  
Huiping Shao ◽  
Jiangcong Qi ◽  
Tao Lin ◽  
Yuling Zhou ◽  
Fucheng Yu
Keyword(s):  
Magnetic Nanoparticles ◽  
Shell Structure ◽  
High Performance ◽  
Cross Linking ◽  
Composite Particles ◽  
Core Shell ◽  
The Core ◽  
Targeting Delivery ◽  
Core Shell Structure ◽  
Chemical Cross Linking

The core–shell structure composite magnetic nanoparticles (NPs), Fe3O4@chitosan@nimodipine (Fe3O4@CS@NMDP), were successfully synthesized by a chemical cross-linking method in this paper. NMDP is widely used for cardiovascular and cerebrovascular disease prevention and treatment, while CS is of biocompatibility. The composite particles were characterized by an X-ray diffractometer (XRD), a Fourier transform infrared spectroscopy (FT-IR), a transmission electron microscopy (TEM), a vibrating sample magnetometers (VSM) and a high performance liquid chromatography (HPLC). The results show that the size of the core–shell structure composite particles is ranging from 12[Formula: see text]nm to 20[Formula: see text]nm and the coating thickness of NMDP is about 2[Formula: see text]nm. The saturation magnetization of core–shell composite NPs is 46.7[Formula: see text]emu/g, which indicates a good potential application for treating cancer by magnetic target delivery. The release percentage of the NMDP can reach 57.6% in a short time of 20[Formula: see text]min in the PBS, and to 100% in a time of 60[Formula: see text]min, which indicates the availability of Fe3O4@CS@NMDP composite NPs for targeting delivery treatment.

scholarly journals Improved Photoresponse Characteristics of a ZnO-Based UV Photodetector by the Formation of an Amorphous SnO2 Shell Layer

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6124
Author(s):  
Junhyuk Yoo ◽  
Uijin Jung ◽  
Bomseumin Jung ◽  
Wenhu Shen ◽  
Jinsub Park
Keyword(s):  
Shell Structure ◽  
Rise Time ◽  
Zno Nanorods ◽  
Wide Bandgap ◽  
Core Shell ◽  
Shell Layer ◽  
Slow Response ◽  
Uv Photodetector ◽  
Zno Nanostructure ◽  
Core Shell Structure

Although ZnO nanostructure-based photodetectors feature a well-established system, they still present difficulties when being used in practical situations due to their slow response time. In this study, we report on how forming an amorphous SnO2 (a-SnO2) shell layer on ZnO nanorods (NRs) enhances the photoresponse speed of a ZnO-based UV photodetector (UV PD). Our suggested UV PD, consisting of a ZnO/a-SnO2 NRs core–shell structure, shows a rise time that is 26 times faster than a UV PD with bare ZnO NRs under 365 nm UV irradiation. In addition, the light responsivity of the ZnO/SnO2 NRs PD simultaneously increases by 3.1 times, which can be attributed to the passivation effects of the coated a-SnO2 shell layer. With a wide bandgap (~4.5 eV), the a-SnO2 shell layer can successfully suppress the oxygen-mediated process on the ZnO NRs surface, improving the photoresponse properties. Therefore, with a fast photoresponse speed and a low fabrication temperature, our as-synthesized, a-SnO2-coated ZnO core–shell structure qualifies as a candidate for ZnO-based PDs.

The use of galvanic displacement in synthesizing Pt(Cu) catalysts with the core-shell structure

2010 ◽  
Vol 46 (10) ◽  
pp. 1189-1197 ◽  
Author(s):  
B. I. Podlovchenko ◽  
T. D. Gladysheva ◽  
A. Yu. Filatov ◽  
L. V. Yashina
Keyword(s):  
Shell Structure ◽  
Core Shell ◽  
Galvanic Displacement ◽  
The Core ◽  
Cu Catalysts ◽  
Core Shell Structure

scholarly journals Synthesis and Control of the Shell Thickness of Polyaniline and Polypyrrole Half Hollow Spheres Using the Polystyrene Cores

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Su-Ryeon Yun ◽  
Gyeong-Ok Kim ◽  
Chan Woo Lee ◽  
Nam-Ju Jo ◽  
Yongku Kang ◽  
...  
Keyword(s):  
Shell Thickness ◽  
Hollow Spheres ◽  
Core Shell ◽  
Chemical Structures ◽  
The Core ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Core Shell Structure ◽  
And Control ◽  
Ft Ir Spectroscopy

Polyaniline (Pani) and polypyrrole (Ppy) half hollow spheres with different shell thicknesses were successfully synthesized by three steps process using polystyrene (PS) as the core. The PS core was synthesized by emulsion polymerization. Aniline and pyrrole monomers were polymerized on the surface of the PS core. The shells of Pani and Ppy were fabricated by adding different amounts of aniline and pyrrole monomers. PS cores were dissolved and removed from the core shell structure by solvent extraction. The thicknesses of the Pani and Ppy half hollow spheres were observed by FE-SEM and FE-TEM. The chemical structures of the Pani and Ppy half hollow spheres were characterized by FT-IR spectroscopy and UV-Vis spectroscopy. The shell thicknesses of the Pani half hollow spheres were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, while the shell thicknesses of the Ppy half hollow spheres were 16.0, 22.0, 27.0, and 34.0 nm. The shell thicknesses of Pani and Ppy half hollow spheres linearly increased as the amount of the monomer increased. Therefore, the shell thickness of the Pani and Ppy half hollow spheres can be controlled in these ranges.

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