Activity evaluation of carbon paste electrodes loaded with pt nanoparticles prepared in different radiolytic conditions

Three Pt-based catalysts prepared in different radiolytic conditions and supported on graphite powder were packed into a carbon paste electrode configuration. They were compared to each other, to the commercial (Pt) deposited on activated carbon powder (Johnson Matthey) and to pure Vulcan XC-72 for their respective abilities toward the hydrogen evolution reaction (HER). The Tafel parameters were determined for all these electrodes. From the I–V curves and their quantitative treatment, the following order of activity emerged unambiguously and reads: (PtCO)₂ (fcc structure) > (PtCO)₁ (Chini cluster) > (Pt)_neat > (Pt)_JM (Johnson Matthey) ≫ (Vulcan XC-72). As expected, all the Pt-loaded electrodes were more efficient than Vulcan XC-72. The classification appears to be linked with the mean nanoparticle size, and for comparable sizes, with the surface morphology of the materials. The results and the stability of the electrodes suggest that the small particle sizes and the good dispersity on the carbon support were maintained during the HER.     

Formation of long range ordered arrangement of quantum dots with the help of lateral centripetal flow

A simple “chimney” method was used to eliminate the voids in an arrangement of quantum dots sized 2 nm on a solid substrate, which resulted in a large well ordered superlattice of area in the order more than 1 μm². Based on the principle of speeding up the interparticle interaction of nanoparticles to overcome the particle-substrate one, a lateral centripetal force originated from a glass tube acting as a chimney in a simple evaporation device is imposed. This method allows the packing process to be controlled in a mechanical force field, that is, with the same nanogold dispersion different patterns on a substrate—from separate dots to an ordered compact monolayer or even a multilayer structure—could be easily obtained.     

巯基丁二胺铜单层修饰金电极上HIV-p24抗原的电化学免疫检测

制备了用巯基丁二胺铜(CuL)修饰的金电极并用作HIV-p24抗原蛋白(简称p24)免疫检测的化学传感器。CuL通过单层自组装固定在金电极表面,其覆盖率为1.02×10-11mol.cm-2,在含有1.0 mmol.L-1过氧化氢并在pH 6.2的磷酸盐缓冲溶液中,制备的校正曲线的线性范围为0.5-150μg.L-1p24对相应的伏安响应,方法的检出限为0.2μg.L-1。在10μg.L-1p24浓度水平作精密度试验,得RSD值为3.5%,于试样中分别加入5,15,20及30μg.L-1p24进行回收率试验,所得结果在98%-102%之间。此方法毋需另加电子传递媒介体。应用此方法于临床血清分析,所得结果与放射性免疫法的结果一致,且所得RSD值均小于0.3%。     

金－钼酸盐－耐尔蓝缔合显色反应的研究

在聚乙烯醇存在下，金与钼酸盐形成络阴离子，继而与耐尔蓝形成离子缔合物，其最大吸收位于５９５ｎｍ，表现摩尔吸光系数ε值为２．７１×１０￣５Ｌ．ｍｏｌ￣（－１）．ｃｍ￣（－１），线性范围０～１６μｇ／２５ｍＬＡｕ，大多数离子不干扰。用于岩矿和冶金产品中金的测定，结果满意。     

纳米氧化铜的制备及常温脱硫效能研究

采用硝酸铜为原料、氢氧化钠溶液为沉淀剂、使用体积比为1∶1的乙醇-水溶液为分散剂的直接沉淀法制备，通过改变工艺条件得到了三种纳米氧化铜产品，平均粒径分别为25.63，10.74和7.57 nm。采用TG-DTA、FIR、XRD和TEM等对纳米氧化铜进行表征。对产品的常温脱硫活性进行了穿透试验，并与已开发的其他常温精脱硫产品进行了比较，结果表明纳米氧化铜应用于H₂S脱硫，可在常温条件下具有优异的脱硫活性，对H₂S的脱除精度可以达到0.05 mg·m^-3以下。经过优选，产品在3 000 h^-1空速下穿透硫容达到25.3%，高于同类型的其他脱硫剂产品。     

聚合物-金属纳米复合材料的制备与应用

综述了聚合物-金属纳米复合材料的制备方法，包括原位形成法、沉积法、离子注入法、辐射化学法、光照化学法、直接分散法、球磨法；介绍了聚合物．金属纳米复合材料的应用领域，最后展望了这种材料的发展前景。     

Influence of the conditions of manufacture of nanomeric zirconium dioxide,stabilized with yttrium oxide,on its catalytic properties in the oxidation of CO

The morphological and catalytic properties of samples of nanomeric zirconium dioxide, stabilized with yttrium oxide, manufactured via the effect of a UHF field during the process of drying precipitated zirconium hydroxide and calcination at temperatures from 300 to 1000 °C, were studied. It was shown that the highest activity in the oxidation of CO occurred with 40 nm particles of zirconium dioxide prepared at 1000 °C. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 96–101, March–April, 2007.     

On the validity of Langmuir adsorption on supported nanoparticles

The general form for adsorption on nanoparticles is presented. Conditions for the validity of Langmuir adsorption isotherm for supported nanoparticles are discussed.     

Photochemical Synthesis and Spectral-Optical Characteristics of ZnO/Cu and ZnO/Ag/Cu Nanoheterostructures

The photoreduction of Cu²⁺ at the surface of ZnO nanoparticles and ZnO/Ag nanostructures was investigated. The spectral characteristics of the obtained ZnO/Cu and ZnO/Ag/Cu composites were studied in relation to the reaction conditions. It was shown that the ZnO/Ag nanoparticles have higher photocatalytic activity in the reduction of Cu²⁺ ions than the individual ZnO particles.     

硫化镉纳米荧光探针荧光猝灭法测定痕量铜

制备了无机纳米溶胶CdS，研究了纳米粒子的大小和荧光性质，以该纳米粒子为探针，建立了荧光猝灭法测定铜离子的新方法。该方法已成功用于人发样品测定，方法简单，快速，选择性好，灵敏度高，在最佳实验条件下，测定铜离子的线性区间为2．0－24．0μg/L，检出限为0．23μg/L。