Uniform Rice-like CdS Particles Prepared from Water-in-oil Microemulsions

IntroductionNano-sized semiconductors are of great interestdue to their special optical and electronic proper-ties[1,2].As one of the mostimportantⅡ—Ⅵsemicon-ductors,CdS has importantapplications in many fields,such as the solar cell field,non linear o…     

磁性纳米包覆微球的制备和磁性表征

以胶体球形粒子为基体发展起来的纳米包覆(nano鄄coating)技术近来引起人们的极大兴趣,这种纳米包覆技术得到的产物常常被称为核壳粒子(core鄄shellparticles)。这种包覆一般是将纳米颗粒直接吸附在核微球上,或者包覆材料控制沉淀在核微球上[1,2]。这些复合微球常常展现出独特的光、电、力学、化学、催化等性质,因而具有广泛的研究和应用前景[3~7]。近十几年来,用做磁感应成像的超顺磁材料得到了深入的研究[4]。一方面,磁性颗粒的尺寸、电荷和表面成分对其应用有很大影响[8,9],另一方面,材料的磁学性质又主要取决于磁颗粒的大小[10]。Xu和Lindlar制备了含超顺磁颗粒的聚合物胶体颗粒,被用于构建超顺磁性的光子晶体[11,12]。在聚合物微粒上包覆氧化铁颗粒通常采用表面沉淀或表面改性官能团诱导反应包覆的方法。但这些方法不能很好控制复合微粒的均一性和表面平整性;Caruso的层鄄层包覆法(Layer鄄byLayer)虽然实现了磁性颗粒包覆[13],然而这种方法非常繁琐而不利于广泛应用。本文报道了一种新的合成磁性包覆颗粒的方法,即以聚合物微球为基核,通过非均相种子生长法包覆磁性纳米颗粒,并研究了...     

双功能型嵌入镍纳米颗粒的碳棱柱状微米棒电极用于电化学甲醇氧化助力的节能产氢

With the rapid development of human society, clean energy forms are imperative to sustain the normal operations of various mechanical and electrical facilities under a cozy environment. Hydrogen is considered among the most promising clean energy sources for the future. Recently, electrochemical water splitting has been considered as one of the most efficient approaches to harvest hydrogen energy, which generates only non-pollutant water on combustion. However, the sluggish anodic oxygen evolution reaction significantly restricts the efficiency of water splitting and requires a relatively high cell voltage to drive the electrolysis. Therefore, seeking a thermodynamically favorable anodic reaction to replace the sluggish oxygen evolution reaction by utilizing highly active bifunctional electrocatalysts for the anodic reaction and hydrogen evolution are crucial for achieving energy-efficient hydrogen production for industrial applications. Nevertheless, it is known that the oxygen evolution reaction can be replaced with other useful and thermodynamically favorable reactions to reduce the electrolysis voltage for realizing energy-efficient hydrogen production. Therefore, in this study, we present a bifunctional nickel nanoparticle-embedded carbon (Ni@C) prism-like microrod electrocatalyst synthesized via a two-step method involving the synthesis of a precursor metal-organic framework-74 and subsequent carbonization treatment for methanol oxidation and hydrogen evolution. The interfacial structure consisting of a nickel and carbon skeleton was realized via in situ carbonization. However, the dispersed nickel nanoparticles do not easily aggregate owing to the partition by the surrounding carbon as it would sufficiently expose the active Ni sites to the electrolytes, ensuring fast charge transfer between the catalyst and electrolytes by accelerating the electrochemical kinetics. In the anodic methanol oxidation, the products were detected as carbon dioxide and formate with faradaic efficiencies of 36.2% and 62.5%, respectively, at an applied potential of 1.55 V. Meanwhile, the Ni@C microrod catalyst demonstrated high activity and durability (2.7% current decay after 12 h of continuous operation) toward methanol oxidation, which demonstrates that methanol oxidation precedes oxidation under voltage forces. Notably, the bifunctional catalyst not only exhibits excellent performance toward methanol oxidation but also yields a low overpotential of 155 mV to drive 10 mA∙cm⁻² toward hydrogen evolution in 1.0 mol∙L⁻¹ KOH aqueous solution with 0.5 mol∙L⁻¹ methanol at room temperature, which guarantees the hydrogen production efficiency. More importantly, the constructed two-electrode electrolyzer produced a current density of 10 mA∙cm⁻² at a low cell voltage of 1.6 V, which decreased by 240 mV after replacing the oxygen evolution reaction with methanol oxidation.     

Characterization of Nested Hollow Inorganic Fullerene-like Tungsten Disulfide Nanoparticles Prepared by Solid-Gas Reaction

Non-carbon inorganic fullerene-like(IF) nanoscale materials have recently attracted intense interest due to their nested hollow and nanotube structures,In this letter,IF-WS2 nanoparticles prepared by solid-gas reaction were characterized by X-ray diffraction,Scanning electron microscopy and transmission electron microscopy.The results show that the IF-WS2 nanoparticles have a nested hollow closed spherical structure with diameter of 100-150mm.     

Synthesis of Molecularly Imprinted Polymer Particles by Suspension Polymerization in Silicon Oil

Molecular imprinting is a method to prepare polymers with recognition site of desired and predetermined selectivity1. Molecularly imprinted polymers (MIP) are prepared by copolymerizing functional and cross-linking monomers in the presence of a molecular …     

均分散胶体的研究 V. 锆化合物均分散颗粒的制备

根据部分稳定氧化锆陶瓷(PSZ)的增韧机制,减小陶瓷粉料ZrO_2颗粒的尺寸是提高陶瓷韧性及其它机械性能的关键,因此合成细微ZrO_2粉料的研究开展得十分活跃.韩利成等用液相沉淀法制备尺寸在微米级以下的氢氧化锆颗粒.村濑嘉夫等在H_2O_2存在下升温水解ZrOCl_2溶液,制备ZrO_2超细颗粒.从所发表的透射电子显微镜(TEM)照片看,他们所制得的颗粒形状和尺寸都不均一,而且粘连,恐难以满足烧制高韧性PSZ     

炉前煤低温干馏工艺中的挥发分除尘

为了寻求优化的炉前煤低温干馏工艺中的挥发分除尘方案，在使用400目金属滤网对间歇式粉煤固体热载体热解装置挥发分除尘研究的基础上，将颗粒床过滤器用于该过程的除尘研究。热态除尘实验表明，颗粒床的使用有效地降低了滤网的过滤负荷。选用2mm石英砂和φ5mm×2mm瓷环作为滤料，通过对比实验发现，两种滤料除尘效率均在90％以上；随着过滤操作的进行，由于颗粒床内粉尘的沉积使其过滤效率有所提高，而对气、液收率的影响很小。结果表明，颗粒床与滤网结合可作为粉煤炉前低温干馏工艺中可供选择的挥发分除尘方案。     

片状化石燃料的循环流化床燃烧(Ⅰ)--片状颗粒的形貌描述和流态化阻力特征描述

比较了不同球形度概念对片状化石燃料的描述效果,研究了片状化石燃料球形度变化对其流态化特征的影响.分析了Krumbein球形度为0.1～0.4的京西无烟煤在一台50MW循环流化床锅炉上表现出来的特殊现象,如运行床温和炉膛压力大幅度波动、依靠排放冷渣保持稳定运行,揭示了这些现象发生的原因.     

氮化烧成后硅在刚玉氮化硅材料中的赋存形态

研究了不同温度氮化烧成后,硅在刚玉氮化硅材料中的赋存形态.结果表明:1300℃氮化后,硅的外层包裹着絮状的O'-Sialon;1400℃时,硅颗粒破裂且内部有氮化硅生成;1 500℃时,已没有残留硅保留下来,硅氮化生成了O'-Sialon和氮化硅;1 600℃时,硅氮化完全,其中的杂质相CaO,Fe2O3等富集在一起.     

WO3粉在高速层间剪切条件下的颗粒破碎特征

研究了WO3粉和W粉的剪切破碎时间对WO3粉和W粉的沉降曲线、平均粒度、BET比表面及松装密度的影响.用TEM和SEM对剪切破碎前后的粉末进行了直接观察.结果表明:新型剪切破碎机能有效地粉碎微米级WO3等脆性粉末,同时可以破坏超细W粉中的桥接团粒,使W粉和WO3粉的松装密度增加1倍以上,但对比表面积影响不大.