Bifunctional Au@Pt hybrid nanorods

The controlled synthesis of bifunctional Au@Pt hybrid nanorods has been realized through a simple wet chemical approach. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis-near infrared spectroscopy (UV-vis-NIR) were employed to characterize the obtained hybrid nanorods. TEM results indicate that the thickness of Pt nanoislands on the surfaces of gold nanorods can be easily tunable via controlling the molar ratio of An nanorods to the H2PtCl6. These Au@Pt hybrid nanorods have dual functions, which can be used not only for surface enhanced Raman spectroscopy (SERS), but also to exhibit good catalytic activity for 02 reduction. It is expected that these hybrid nanorods can be used as new functional building blocks to assemble novel three-dimensional (31)) complex multicomponent nanostructures, which are believed to be useful for electrochemical nanodevices.

Self-assembly of ionic liquids-stabilized Pt nanoparticles into two-dimensional patterned nanostructures at the air-water interface

In this paper, we demonstrate the self-assembly of ionic liquids (ILs)-stabilized Pt nanoparticles into two-dimensional (2D) patterned nanostructures at the air-water interface under ambient conditions. Here, ILs are not used as solvents but as mediators by virtue of their pronounced self-organization ability in synthesis of self-assembled, highly organized hybrid Pt nanostructures. It is also found that the morphologies of the 2D patterned nanostructures are directly connected with the quantities of ILs. Due to the special structures of ILs-stabilized Pt nanoparticles, 2D patterned Pt nanostructures can be formed through the pi-pi stack interactions and hydrogen bonds. The resulting 2D patterned Pt nanostructures exhibit good electrocatalytic activity toward oxygen reduction.

硅（111）和金（111）基底自组装膜表面纳米图案化与功能化

利用导电原子力显微镜在烷基化自组膜/Si(111)和巯基自组膜/Au(111)上加工纳米模板,结合组装的方法构建功能化纳米图案。在烷基化自组膜/Si(111)上施加偏压可以得到SiO2纳米图案,此图案可以做功能化模板,将图案化区域组装胺基作为端基的硅烷后,通过1-乙基-3-（3-二甲基氨基丙基）碳二亚胺盐酸盐(EDC)/N-羟基琥珀酰亚胺(NHS)试剂活化共价结合11-巯基十一酸(MUA)稳定的金纳米粒子,得到金纳米粒子功能化纳米图案。在烷基硫醇自组装膜/Au(111)施加偏压可以选择性移除自组装膜,移除自组装膜后新暴露的金可以用做纳米模板,在此模板上组装MUA后通过EDC/NHS活化共价键合溶菌酶,得到蛋白质功能化的纳米点阵图案。

The real role of carbon in Pt/C catalysts for oxygen reduction reaction

A new electrocatalysis of carbon materials for oxygen reduction reaction (ORR) on Pt/C catalysts was discovered. It was found that there exist two kinds of electroactive sites on these supports of carbon materials, which can effectively electrocatalyze the reduction of peroxide intermediated from oxygen reduction on Pt, as this provides continuous driving force to move the equilibrium toward the production of peroxide from ORR.

Enhancement of the electrooxidation of ethanol on Pt-Sn-P/C catalysts prepared by chemical deposition process

In this paper, five Pt3Sn1/C catalysts have been prepared using three different methods. It was found that phosphorus deposited on the surface of carbon with Pt and Sn when sodium hypophosphite was used as reducing agent by optimization of synthetic conditions such as pH in the synthetic solution and temperature. The deposition of phosphorus should be effective on the size reduction and markedly reduces PtSn nanoparticle size, and raise electrochemical active surface (EAS) area of catalyst and improve the catalytic performance. TEM images show PtSnP nanoparticles are highly dispersed on the carbon surface with average diameters of 2 nm. The optimum composition is Pt3Sn1P2/C (note PtSn/C-3) catalyst in my work. With this composition, it shows very high activity for the electrooxidation of ethanol and exhibit enhanced performance compared with other two Pt3Sn1/C catalysts that prepared using ethylene glycol reduction method (note PtSn/C-EG) and borohydride reduction method (note PtSn/-B). The maximum power densities of direct ethanol fuel cell (DEFC) were 61 mW cm(-2) that is 150 and 170% higher than that of the PtSn/C-EG and PtSn/C-B catalyst.

The enhancement effect of Eu3+ on electro-oxidation of ethanol at Pt electrode

It is reported for the first time that the slow electrochemical kinetics process for the electro-oxidation of ethanol can be promoted by changing the electrochemical environment. The electro-oxidation of ethanol at a Pt electrode in the presence of Eu3+ cations was studied and an enhancement effect was exhibited. Cyclic voltammetry experiment results showed that the peak current density for the electro-oxidation of ethanol was increased in the presence of EU3+ in the ethanol solution. A preliminary discussion of the mechanism of the enhancement effect is given. This is based on a CO stripping experiment, which shows that either the onset potential or the peak potential of CO oxidation is shifted negatively after adding Eu3+ to the solution.

Large-scale, uniform DNA network on 11-mercaptoundecanoic acid modified gold (111) surface: Atomic force microscopy study

Large-scale, uniform plasmid deoxyribonucleic acid (DNA) network has been successfully constructed on 11-mercaptoundecanoic acid modified gold (111) surface using a self-assembly technique. The effect of DNA concentration on the characteristics of the DNA network was investigated by atomic force microscopy. It was found that the size of meshes and the height of fibers in the DNA network could be controlled by varying the concentration of DNA with a constant time of assembly of 24 h.

Synthesis and assembly of Au-Pt bimetallic nanoparticles

Au-Pt bimetallic nanoparticles (NPs) were synthesized by reducing the mixture of HAuCl4 and K2PtCl6 with ethanol in the presence of cinnamic acid (C6H5CHCHCO2H, CA) through a thermal process. It was found that the isolated NPs could gradually self-assemble into chain-like structures, ultimately to 3-dimensional network nanostructures by adjusting the molar ratio of CA to K2PtCl6. Energy-dispersive Spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction was used to confirm the formation of Au-Pt bimetallic nanostructures. It was worthwhile noting that the bimetallic NPs with the novel structures prepared by our method exhibited an attractive catalytic activity for the hydrogen evolution reaction in an acidic solution.

纳米管结构对碳纳米管载Pt催化剂电催化性能的影响

在制备单、双壁及不同管径的多壁碳纳米管(CNTs)的基础上,用液相还原法把Pt沉积到单、双壁和管径不同的多壁CNTs上.发现制得的CNTs载Pt(Pt/CNTs)催化剂对甲醇氧化的电催化活性随CNTs管径减小而增加.这归结于管径小的CNTs的比表面积较大,含氧基团多,有利于提高Pt粒子分散度,加上管径小的单壁CNTs具有更高的导电性,这些因素都有利于提高Pt/CNTs催化剂对甲醇氧化的电催化活性.

不同载量Pt/C催化剂制备及其对甲醇氧化的电催化活性

用甲醇作溶剂,SnCl2作还原剂,采用改进的有机溶胶方法制备了用于直接甲醇燃料电池(DMFC)中甲醇氧化的炭载Pt(Pt/C)催化剂。制得的Pt/C催化剂中的Pt粒子具有高度的均一性和良好的分散度。通过控制溶剂的蒸发温度,能够获得Pt粒子平均粒径基本相同、Pt载质量分数为10%～60%的Pt/C催化剂,粒径为3.3～4.3nm。将获得的催化剂通过涂膜-热压法制备成DMFC膜电极,研究了Pt载量对甲醇电催化氧化性能的影响。结果表明,质量分数为40%的Pt/C催化剂对甲醇的电催化氧化显示出优异的电催化性能。

Fe对Pt-Fe/C催化剂电催化氧还原反应活性的影响

制备了用作直接甲醇燃料电池的碳载Pt-Fe(Pt-Fe/C)阴极催化剂,X射线能量色散谱(EDX)、X射线衍射谱和电化学测量的结果表明,在Pt-Fe/C催化剂中,Fe以3种形式存在.质量分数大约为20%的Fe进入Pt的晶格,形成Pt-Fe合金,质量分数大约为80%的Fe没有进入Pt的晶格而以Fe和Fe2O3的形式单独存在.该催化剂经酸处理后,非合金化Fe和Fe2O3被溶解,而使Pt-Fe/C催化剂的电化学活性比表面积要比未经酸处理前的增加约30%左右,导致Pt-Fe/C催化剂对氧还原的电催化活性优于未经酸处理前的Pt-Fe/C催化剂.研究结果表明,Pt-Fe/C催化剂的电化学活性比表面积对氧还原的电催化活性起重要的作用,另外,只有与Pt形成合金的Fe能提高Pt对氧还原的电催化活性,而非合金化的Fe对Pt催化剂对氧还原的电催化活性基本没有影响.