Pt nanoparticles: Heat treatment-based preparation and Ru(bpy)(3)(2+)-mediated formation of aggregates that can form stable films on bare solid electrode surfaces for solid-state electrochemiluminescence detection

A simple thermal process for the preparation of small Pt nanoparticles is presented, carried out by heating a H-2-PtCl6/3- thiophenemalonic acid aqueous solution. The following treatment of such colloidal Pt solution with Ru( bpy)(3)(2+) causes the assembly of Pt nanoparticles into aggregates. Most importantly, directly placing such aggregates on bare solid electrode surfaces can produce very stable films exhibiting excellent electrochemiluminescence behaviors.

Electrooxidation of COad intermediated from methanol oxidation on polycrystalline Pt electrode

The poisonous intermediate of methanol oxidation on a Pt electrode was validated to be COad by electrochemical method. An approximate treatment to bimolecular elementary reactions on an electrode was advanced and then was applied to the stripping normal pulse voltammetry (NPV) for complex multistep multielectron transfer processes on plane electrodes to study the kinetics of completely irreversible process Of COad oxidation to CO2. The kinetic parameters for this process, such as standard rate constant (0) and anodic transfer coefficient (alpha) for this irreversible heterogeneous electron-transfer process at electrode/solution interface and apparent diffusion coefficient (D-app) for charge-transfer process within the monolayer of COad on electrode surface, were obtained with stripping NPV method. The effect of the approximate treatment on the kinetic parameters was also analyzed.

Preparation of a carbon supported Pt catalyst using an improved organic sol method and its electrocatalytic activity for methanol oxidation

The organic sol method for preparing ultrafine transition metal colloid particles reported for the first time by Bonnemann et al. [H. Bonnemann, W Brijoux, R. Brinkmann, E. Dinjus, T. Jou beta en, B. Korall, Angew. Chem. Int. Ed. Engl., 30 (1991) 1312] has been improved in this paper. The improved organic sol method uses SnCl2 as the reductant and methanol as the organic solvent. Thus, this method is very simple and inexpensive. It was found that the average size of the Pt particles in the Pt/C catalysts can be controlled by adjusting the evaporating temperature of the solvent. Therefore, the Pt/C catalysts prepared by the same method are suitable for evaluating the size effect of the Pt particles on electrocatalytic performance for methanol oxidation. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that when the evaporating temperatures of the solvent are 65, 60, 50, 40, and 30 degrees C, the average sizes of the Pt particles in the Pt/C catalysts prepared are: 2.2, 3.2, 3.8, 4.3, and 4.8 nm, respectively. The X-ray photoelectron spectroscopic (XPS) results demonstrated that the small Pt particles are easily oxidized and the decomposition/adsorption of methanol cannot proceed on the surfaces of Pt oxides.

Synthesis of Pt/Ag bimetallic nanorattle with Au core

A straightforward combination of the seeding growth method and replacement reaction allowed for the formation of a nanorattle composed of a gold core and Pt/Ag shell. The size, structure, and composition of the Pt/Ag rattle-type nanostructure were confirmed by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrometry.

Rapid synthesis of cubic Pt nanoparticies and their use for the preparation of Pt nanoagglomerates

We report the synthesis of hexadecyltrimethylammonium bromide (CTAB)-stabilized cubic Pt nanoparticles by NaBH4 reduction of H2PtCl6 in aqueous CTAB solution. These Pt nanoparticles (average size of 7 nm) were well dispersed in aqueous solution and stable at least for 2 months. Addition of a trace amount of AgNO3 can alter the morphology of these Pt nanoparticles. More interestingly, the as-prepared uniform Pt nanoparticles were further developed into bigger Pt nanoagglomerates (similar to 20 to 47 nm) by a seed-mediate growth process. Dentritic and spherical Pt nanoagglomerates can be synthesized by altering the incubation time and their size can be tuned by controlling the amount of the seeds added.

Simple and convenient preparation of Au-Pt core-shell nanoparticles on surface via a seed growth method

Au-Pt core-shell nanoparticles were prepared on glass surface by a seed growth method. Gold nanoparticles were used as seeds and ascorbic acid-H2PtCL6 solutions as growth solutions to deposit Pt shell on the surface of gold nanoparticles. These core-shell nanoparticles and their growth process were examined by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and field-emission environmental scanning electron microscopy and the results indicated that the deposition speed was fast and nanoparticles with obvious core-shell structure could be obtained after 2 min. Moreover, this seed growth method for preparation of the core-shell nanoparticles is simple and convenient compared with other seed growth methods with NH4OH as a mild reductant. In addition, electrochemical experiments indicated that these Au-Pt core-shell nanoparticles had similar electrochemical properties to those of the bulk Pt electrode.

Effect of borohydride as reducing agent on the structures and electrochemical properties of Pt/C catalyst

In this paper, we found that boron deposited on the surface of support when sodium borohydride used as reducing agent during the preparation of Pt/C catalyst. The deposition of boron markedly reduces particle size of Pt, raises electrochemical active surface (EAS) area of catalyst and electrochemical activity for hydrogen evolution or oxygen reduction reaction (ORR) compared with which prepared using other reducing agents (hydrogen and formaldehyde).

合金化程度对炭载Pt-Ru催化剂性能的影响

在含四氢呋喃(THF)的水溶液中,室温下用NaBH4还原H2PtC l6和RuC l3制得Pt-Ru/C催化剂.其Pt-Ru粒子的合金化程度较高,平均粒径较小,相对结晶度较低.因此对甲醇氧化的电催化活性远高于Pt-Ru粒子的平均粒径和相对结晶度相似的,而且Pt-Ru合金化程度低的商业化的E-TEK的Pt-Ru/C催化剂,表明Pt-Ru的合金化程度对Pt-Ru/C催化甲醇氧化的电催化活性有很大的影响.

一种制备碳载高合金化Pt-Ru催化剂的方法

提出了在四氢呋喃(THF)和H2O混合溶液中用一般的化学还原法在室温下制备碳载Pt-Ru(Pt-Ru/C)催化剂的新方法。与在纯水中制得的Pt-Ru/C催化剂相比,其Pt-Ru粒子的合金化程度高、平均粒径较小且相对结晶度低,因此,该催化剂对甲醇氧化的电催化活性远高于在纯水中制得的Pt-Ru/C催化剂。高合金化程度的原因是H2PtCl6和RuCl3在THF和H2O混合溶液中的起始还原电位相近。此外,在THF和H2O混合溶液中,THF和H2O的体积比的改变并不影响制得的Pt-Ru/C催化剂中Pt-Ru粒子的合金化程度,但对Pt-Ru粒子的粒径以及相对结晶度有较大影响。

碳纳米管表面修饰程度对碳纳米管载Pt电催化性能的影响

比较了用不同温度的浓HNO3处理的碳纳米管(CNTs)作载体的Pt(Pt/CNTs)对甲醇氧化的电催化活性.结果表明浓HNO3处理使CNTs表面修饰上的含氧基团对CNTs上沉积Pt粒子的平均粒径有较大影响.表面修饰程度适当时,制得的Pt/CNTs中Pt粒子较小,因此,对甲醇氧化的电催化活性较高.而表面修饰程度过大,易使Pt粒子团聚,从而降低Pt/CNTs催化剂对甲醇氧化的电化学活性.

Preparation of multilayer films containing pt nanoparticles on a glassy carbon electrode and application as an electrocatalyst for dioxygen reduction

In this paper, a simple route for the preparation of Pt nanoparticles is described. PtCl62- and [tetrakis-(N-methylpyridyl)porphyrinato] cobalt (CoTMPyP) were assembled on a 4-aminobenzoic acid modified glassy carbon electrode through the layer-by-layer method. The three-dimensional Pt nanoparticle films are directly formed on an electrode surface by electrochemical reduction of PtCl62- sandwiched between CoTMPyP layers. Regular growth of the multilayer films is monitored by UV-vis spectroscopy. X-ray photoelectron spectroscopy verifies the constant composition of the multilayer films containing Pt nanoparticles. Atomic force microscopy proves that the as-prepared Pt nanoparticles are uniformily distributed with average particle diameters of 6-10 nm. The resulting multilayer films containing Pt nanoparticles on the modified electrode possess catalytic activity for the reduction of dissolved oxygen. Rotating disk electrode voltammetry and rotating ring-disk electrode voltammetry confirm that Pt nanoparticle containing films can catalyze an almost four-electron reduction of O-2 to water in 0.5 M H2SO4 solution.

Defect formation induced by PAMAM dendrimers on Pt-supported bilayer lipid membranes investigated by electrochemistry

The interaction of polyamidoamine (PAMAM) dendrimers (generations 1-7) with supported bilayer lipid membranes was studied by cyclic votammetry and ac impedance. It is shown that the dendrimers (generations 4-6) can induce defects in the Pt-electrode-supported bilayer lipid membrane. The ability of dendrimers to induce defects was dependent on their shapes and surface charge. The results are consistent with a change in the morphology of the dendrimers from an open, branched structure for generations 1-4 to a closed, increasingly compact surface for generations 5-7.

Pt羰基簇合物途径制备的Pt/C催化剂对甲醇的电催化氧化

通过Pt羰基簇合物在N2气氛下于150℃热分解制得了无定形的碳载纳米Pt催化剂.发现甲醇在这种催化剂上氧化的起始电位和峰电位均比在传统的液相还原法制得的Pt/C催化剂上发生了负移,峰电流也有明显的增加,且稳定性好.表明通过Pt羰基簇合物热分解制备Pt/C催化剂是一种较好的制备甲醇氧化电催化剂的方法.