scholarly journals Combining the core-shell construction with an alloying effect for high efficiency ethanol electrooxidation

2021 ◽  
pp. 100357
Author(s):  
Danye Liu ◽  
Qing Zeng ◽  
Hui Liu ◽  
Chaoquan Hu ◽  
Dong Chen ◽  
...  
2011 ◽  
Vol 90-93 ◽  
pp. 1702-1705
Author(s):  
Xi Zhang ◽  
Gang Xiang

We demonstrate the design of the recyclable photocatalyst based on ferromagnetic (FM) ZnO- TiO2 core-shell nanowires (NWs). Since the band gaps and band edge energies of bulk ZnO and anatase TiO2 are equal to each other within about 45mV, TiO2 and ZnO can form an p-p+ heterojunction free of band discontinuities and with a built-in potential. The resulting radial field will increase hole density in the TiO2 layer while reduce hole concentration at the interface between the core and the shell, which in turn will decrease the rate of recombination in the photocatalytic TiO2, and hence increase the efficiency of photocatalyst. On the other hand, the NWs with FM cores can be easily collected and refreshed using solenoid and suitable for the recyclable usage of the NW catalyst


2015 ◽  
Vol 63 (1) ◽  
pp. 14-28 ◽  
Author(s):  
Tereza Hájková ◽  
Andrea Kalendova

Purpose – This paper aims to synthesise anticorrosion pigments containing molybdenum for paints intended for corrosion protection of metals. Design/methodology/approach – The anticorrosion pigments were prepared by high-temperature solid-state synthesis from the appropriate oxides, carbonates and calcium metasilicate. Stoichiometric molybdates and core-shell molybdates with a non-isometric particle shape containing Ca, Sr, Zn, Mg and Fe were synthesised. The pigments were examined by X-ray diffraction analysis and scanning electron microscopy. Paints based on an epoxy resin and containing the substances at a pigment volume concentration of 10 volume per cent were prepared. The paints were subjected to physico-mechanical tests and to tests in corrosion atmospheres. The corrosion test results were compared to those of the paint with a commercial pigment, which is used in many industrial applications. Findings – The molybdate structure of each pigment prepared was elucidated. The core-shell molybdates exhibit a non-isometric particle shape. The pigments prepared were found to impart a very good anticorrosion efficiency to the paints. A high anticorrosion efficiency was found with the pigments Fe2(MoO4)3 and Fe2(MoO4)3/CaSiO3 and with Mg and Zn molybdates. Practical implications – The pigments can be used for the formulation of paints intended for the corrosion protection of metals. The pigments also improve the paints’ physical properties. Originality/value – The use of the pigments in anticorrosion paints for the protection of metals is new. The benefits include the use and the procedure of synthesis of the anticorrosion pigments which are free from heavy metals and are acceptable from the aspect of environmental protection. Moreover, the core-shell molybdates, whose high efficiency is comparable to that of the stoichiometric molybdates, have lower molybdenum contents.


2020 ◽  
Vol 22 (18) ◽  
pp. 6157-6169 ◽  
Author(s):  
Xinming Wang ◽  
Zemin Feng ◽  
Boxin Xiao ◽  
Jingxiang Zhao ◽  
Huiyuan Ma ◽  
...  

The core–shell structure of the Fe1.89Mo4.11O7/FeS2@C hybrid material exhibits high-efficiency electrocatalytic NRR activity and stability under ambient conditions.


2021 ◽  
Vol 237 ◽  
pp. 01009
Author(s):  
Hao Liu ◽  
Tianwei Zhang ◽  
Cunwei Zhang ◽  
Lei Xiao ◽  
Qiang Liang

Water has unsurpassed capabilities in fire extinguishing. However, water scarcity is rapidly increasing in many regions and water shortage problems have led to find either new water resources or improve seawater treatment technologies. In this study, a new environment-friendly and high-efficiency powdered fire extinguishing agent with a core-shell structure is designed. The designed extinguishing agent is a colloidal powder with a 92% liquid content and is prepared through physical modification and high-speed shearing. Fumed silica is used for the external shell due to its chemical inertness, whereas seawater is used as the core due to its high extinguishing efficiency. Results show that the size of the prepared agent ranged between 100–200μm. The two fire extinguishing experiments of different scales demonstrate that the employing inorganic salts with seawater as the core can significantly increase the efficiency of the new powder in extinguishing gasoline and diesel fire compared with ultrafine and common ABC dry powders. The suppression mechanism of action is caused by the combined flame chemical and pyrolysis theories of the potassium compounds. This study would be of great theoretical significance and application value for improving the application scope of the seawater.


2005 ◽  
Author(s):  
Ronggui Yang ◽  
Gang Chen ◽  
Mildred S. Dresselhaus

Core-shell heterostructures could potentially become the building blocks of nanotechnology for electronic and optoelectronic applications. The increased surface or interface area will decrease the thermal conductivity of such nanostructures and impose challenges for the thermal management such devices. In the mean time, the decreased thermal conductivity might benefit the thermoelectric conversion efficiency. In this paper, a generic model is established to study phonon transport in core-shell nanowire structures in the longitudinal direction using the phonon Boltzmann equation. The model can be used to simulate a variety of nanostructures, including nanowires and nanocomposites by changing some of the input parameters. We first report the dependence of the thermal conductivity on the surface conditions and the core-shell geometry for silicon core - germanium shell and tubular silicon nanowires. When the scattering at the outer shell surface in the generic model is assumed to be totally specular, the core-shell nanostructure resembles a simulation unit cell of periodic two-dimensional (2-D) nanocomposites. Thermal conductivity of nanowire composites and cylindrical nanoporous material in longitudinal direction is thus predicted as a function of the size of the nanowires and nanopores, and the volumetric fraction of the constituent materials. Results of this study can be used to direct the development of high efficiency thermoelectric materials.


2015 ◽  
Vol 62 (5) ◽  
pp. 307-321 ◽  
Author(s):  
Andrea Kalendova ◽  
Tereza Hájková

Purpose – This paper aims to synthesize anticorrosion pigments containing tungsten for paints intended for corrosion protection of metals. Design/methodology/approach – The anticorrosion pigments were prepared by high-temperature, solid-state synthesis from the respective oxides, carbonates and calcium metasilicate. Stoichiometric tungstates and core-shell tungstates with a nonisometric particle shape containing Ca, Sr, Zn, Mg and Fe were synthesized. The pigments were examined by X-ray diffraction analysis and by scanning electron microscopy. Paints based on an epoxy resin and containing the substances at a pigment volume concentration (PVC) = 10 volume per cent were prepared. The paints were subjected to physico-mechanical tests and to tests in corrosion atmospheres. The corrosion test results were compared to those of the paint with a commercial pigment, which is used in many industrial applications. Findings – The tungstate structure of each pigment was elucidated. The core-shell tungstates exhibit a nonisometric particle shape. The pigments prepared were found to impart a very good anticorrosion efficiency to the paints. A high efficiency was demonstrated for the stoichiometric tungstates containing Fe and Zn and for core-shell tungstates containing Mg and Zn. Practical implications – The pigments can be used with advantage for the formulation of paints intended for corrosion protection of metals. The pigments also improve the paints’ physical properties. Originality/value – The use of the pigments in anticorrosion paints for the protection of metals is new. The benefits include the use and the procedure of synthesis of anticorrosion pigments which are free from heavy metals and are acceptable from the environmental protection point of view. Moreover, the core-shell tungstates, whose high efficiency is comparable to that of the stoichiometric tungstates, have lower tungsten content.


2020 ◽  
Vol 818 ◽  
pp. 152861 ◽  
Author(s):  
Dong Liu ◽  
Yan Zhang ◽  
Chenhui Zhou ◽  
Huipeng Lv ◽  
Song Chen ◽  
...  

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.


Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.


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