Search

Spherical (Zr.2Ti.2Ta.2Nb.2Mo.2)B2 powders with a uniform particle size distribution are successfully prepared using a novel industrial approach, which combines spray‐drying process and thermal plasma sintering technology together. In this, single‐phase (Zr.2Ti.2Ta.2Nb.2Mo.2)B2 powders are first synthesized via a borothermal reduction process using a mixture of individual metallic oxides and boron powders as starting materials. The influence of boron powder content on the structure of prepared powders is researched. Then, (Zr.2Ti.2Ta.2Nb.2Mo.2)B2 granules are prepared after wet‐grinding and spray‐drying process, which exhibit a spherical shape and homogeneous element distribution. RF induction thermal plasma is finally used to sinter the granulated particle, and the apparent density of sintered spherical powders is increased to 2.57 g/cm3 from 1.43 g/cm3. Such powders are in potential demand for additive manufacturing techniques, and the successful synthesis of spherical (Zr.2Ti.2Ta.2Nb.2Mo.2)B2 powders may guide the way toward the preparation of many other spherical high‐entropy diboride powders. [ABSTRACT FROM AUTHOR]

The reduction of CO2 to chemical fuel driven by solar energy can not only meet the growing demand for renewable energy, but also balance the carbon cycle in nature. However, the current photocatalysts have low CO2 conversion due to their poor light capture ability, narrow light response range, and high recombination probability of photogenerated carriers. Herein, a heterogeneous photocatalyst of hollow structured ZnO/ZnS decorated with Pt nanoparticles is synthesized through the hydrothermal process and photodeposition method, showing excellent photocatalytic activity for CO2 reduction in long‐time stability and ≈100% CO selectivity, which can mainly contribute to natural enhanced light‐capture ability of the hollow confined space due to multiple reflection and scattering of light in the cavity, thus improving separation efficiency of photogenerated charge carriers due to the type II junction constructed between ZnO and ZnS and the additional reaction active sites after decorating Pt nanoparticles in the surface of the hollow structure. [ABSTRACT FROM AUTHOR]

Silicon (Si) anode materials have been extensively studied due to high capacity and abundant reserves. Herein, inspired by the Li+‐inert components, we design a novel silicon/iron silicide nanoparticles (Si/FeSi2 NPs) prepared by thermal plasma to achieve stress‐releasing effect. The Si/FeSi2 NPs is composed of Si and FeSi2 which exhibits superhigh Initial Coulomb Efficiency (ICE, 89%) with a capacity of 1121 mAh g−1 after 850 cycles. The mechanism of the FeSi2 phase in the Si/FeSi2 NPs is studied by using finite element modelling creatively, demonstrating that the FeSi2 phase can buffer the volume expansion effectively by reducing the stress concentration on the particles surface and releasing internal stress of particles, thus maintaining structural integrity. After combining with carbon coating layer, the Si/FeSi2/carbon/graphite materials (Si/FeSi2/C/G) can achieve superior electrochemical performances. This work provides new insight into the development of the structural stable Si‐alloy anodes towards LIBs applications. [ABSTRACT FROM AUTHOR]

Abstract: A two‐step reduction route is proposed for well‐dispersed submicrometer ZrB2 powder synthesis with low oxygen content. The second synthesis step can reduce the oxygen content apparently, whereas presents minor adverse effects on particle size and dispersion of ZrB2 powders. The samples were mainly characterized by an oxygen‐nitrogen analyzer and X‐ray diffractometer (XRD). It can be determined that the adsorbed oxygen constitutes a low proportion of total oxygen content based on the release profile of oxygen and nitrogen contents. Besides, the oxygen content calculated based on XRD characterization is significantly lower than the total oxygen content measured by impulse‐thermal conductivity. Furthermore, the lattice constants were determined according to XRD patterns as being higher than the calculated theoretical values based on the First‐Principles, indicating that a portion of oxygen remains in ZrB2 powders in the form of interstitial impurity atoms. [ABSTRACT FROM AUTHOR]

ZrB2 and ZrC powders were synthesized via metallothermic reduction route using ZrO2, B/C, and Mg as raw materials. Low packing density of the green mixture and high heating temperature of the furnace are crucial for the formation of well-dispersed submicro powders. Optimum reaction time helped achieve good crystallization and high purity. The as-prepared samples were characterized by XRD, FESEM, TEM, and particle size analyzer. Results showed that well-dispersed ZrB2 powders with mean particle size of 0.534 μm and ZrC powders with mean particle size of 0.376 μm can be obtained. Oxygen content can be controlled lower than 1.0 wt%. The bench-scale output is about 10 kg/d. [ABSTRACT FROM AUTHOR]

A radio-frequency atmospheric-pressure plasma process has been applied to the synthesis of ultrafine ZrC powders using ZrCl4 and CH4 as precursors. Both thermodynamic analysis and experiments were conducted and the as-prepared samples were characterized by X-ray diffraction, electron microscopy, and laser scattering. Results showed that ZrC powders with particle size <100 nm and surface area of 36.56 M2/g could be obtained. The addition of excess H2 contributed to the increase in conversion rate. The conversion rate was about 65% when the carrier gas ratio ( H2/ CH4) was set at 4.0 and added axially through the injection probe. [ABSTRACT FROM AUTHOR]

A simple hydrothermal method has been used to synthesize 3D ZnO architectures without any surfactants. The assemblies were composed of thin nanoplates with the thickness of about 35nm. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) characterized the structure, morphology and optical property of products. The thickness of plates and assembly pattern can be controlled by adjusting the experimental parameters. Furthermore, these ZnO nanoplate assemblies exhibited enhanced photocatalytic activity in the degradation of methylene blue (MB). (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]