Effect of pretreatment of black carbon on electrocatalytic activity of Pt/C catalyst for methanol oxidation

Direct methanol fuel cell (DMFC) has attracted wide attention due to its many advantages. However, its practical application is limited by the low electrocatalytic activity of the anodic Pt/C catalyst usually used for the methanol oxidation. In this paper, in order to increase the electrocatalytic performance of the Pt/C catalyst for the methanol oxidation, the black carbon, usually used as the supporter, was pretreated with CO2, air, HNO3 or H2O2. The cyclic voltarnmetric results indicated that the current densities of the anodic peak of methanol oxidation at the Pt/C catalysts with the black carbon pretreated with CO2,air, HN03, H202 and untreated black carbon were 39, 33, 32, 20 and 18 mA center dot cm(-2), respectively, illustrating that among the above five kinds of the Pt/C catalysts, the Pt/C catalyst with the black carbon pretreated with CO2 shows the best electrocatalytic activity and stability for the methanol oxidation. Its main reason is that the CO2 pretreatment could reduce the content of the oxygen-containing groups on the surface of the black carbon and increase the content of graphite in the black carbon, leading to the low resistance of the black carbon and the increase in the dispersion extent of the Pt particles in the Pt/C catalyst.

碳黑预处理对Pt/C催化剂对甲醇氧化电催化活性的影响

直接甲醇燃料电池(DMFC)由于具有较多的优点而受到广泛的关注.但是碳载Pt(Pt/C)阳极催化剂电催化活性低是限制其应用的一个主要问题.为了提高Pt/C催化剂对甲醇氧化的电催化性能,分别用CO2,空气,H2O2或HNO3对常用作为载体的VulcanXC-72碳黑进行预处理.结果表明,在用CO2,空气,HNO3,H2O2处理的及未处理的碳黑作载体制得的Pt/C催化剂电极上,甲醇氧化峰的峰电流密度顺序为39,33,32,20和18mA?cm-2,表明用CO2处理的碳载体制备的Pt/C催化剂对甲醇氧化有最好的电催化活性和稳定性.其主要原因是用CO2处理能减少碳黑表面的含氧基团和增加石墨化程度,而使碳黑的电阻降低及Pt粒子在碳黑上的分散性变好.

CoTPP-Pt/C作直接甲醇燃料电池阴极催化剂

制备了炭载四苯基钴卟啉(CoTPP)和Pt(CoTPP-Pt/C)复合催化剂,研究了炭载四苯基铁卟啉对氧还原的电催活性。电化学研究发现,CoTPP-Pt/C催化剂对氧还原有很高的电催化活性。CoTPP-Pt/C催化剂对氧还原的极限电流密度比Pt/C催化剂高30%左右,但抗甲醇的能力未改善。

Electronic structures of MCO (M = Nb, Ta, Rh, Ir, Pd, Pt) molecules by density functional theory

Equilibrium geometries, vibrational frequencies, and dissociation energies of the transition metal carbonyls MCO (M = Nb, Ta, Rh, Ir, Pd, Pt) were studied by use of diverse density functional methods B3LYP, BLYP, B3P86, B3PW91, BHLYP, BP86, and PBE1PBE. It was found that the ground electronic state is (6)Sigma(+) for NbCO and TaCO, (2)Sigma(+) for RhCO,(2)Delta for IrCO, and (1)Sigma(+) for PdCO and PtCO, in agreement with previous theoretical studies. The calculated properties are highly dependent on the functionals employed, in particular for the dissociation energy. For most of the molecules, the predicted bond distance is in agreement with experiments and previous theoretical results. BHLYP is the worst method in reproducing the experimental results compared with the other density functional methods for the title molecules.

碳纳米管纯化对Pt/CNTs催化甲醇电化学氧化活性的影响

探索了一种适用于 Pt/CNTs催化剂的纯化方法 .利用比表面积测定、 X射线衍射 ( XRD)、透射电子显微镜 ( TEM)和电化学等手段进行了表征 .研究结果表明 ,经该方法纯化的 CNTs作为载体制备的阳极催化剂表现出明显优于相应的混酸氧化法纯化的 CNTs为载体的催化剂催化性能

固相反应法制备Pt-Ru/C催化剂对乙醇氧化的电催化活性研究

引言近年来,直接甲醇燃料电池(DMFC)由于其燃料来源丰富、价格低廉、甲醇携带和储存安全方便等独特的优越性而越来越受到重视[1]。但是甲醇具有一定的毒性,因此要想实现DMFC在诸如手机、笔记本电脑以及电动车等可移动电源领域的应用,必须探索新的液体燃料以替代有毒性的甲醇。其中乙醇很易从农作物中大量生产,又无毒,因此很有可能用作替代甲醇的质子交换膜燃料电池燃料。近年来乙醇的电催化氧化已被众多的研究者从电催化和乙醇燃料电池的角度进行了广泛的研究[2,3]。但是乙醇在Pt电极上的氧化易导致强吸附物种CO毒化催化剂,Pt鄄Ru合金是目前强吸附毒化物种CO易氧化为CO2的最有效的电催化剂,因此近年来也有一些关于Pt鄄Ru合金催化剂对乙醇的电化学氧化的研究[4~6]。我们研究组首次用固相反应法制备了Pt/C催化剂,发现所制得的Pt/C催化剂对甲醇[7]和乙醇[8]氧化的电催化性能要比用传统的液相反应法制得的Pt/C催化剂好很多。但Pt/C催化剂对甲醇和乙醇氧化的电催化活性还是较低,因此,本文首次研究了用固相反应法制备Pt鄄Ru/C催化剂及这种催化剂对乙醇氧化的电催化性能,发现用固相反应法制备的Pt鄄Ru/C催化剂对乙醇氧...

吸附在Pt/C催化剂上Eu~(3+)对CO电氧化的促进作用

引言目前影响质子交换膜燃料电池(PEMFC)迅速发展并商业化的主要问题之一是阳极催化剂抗CO的毒化能力。Pt因其对氢的氧化具有高的催化活性而广泛地用作PEMFC的阳极催化剂,也有人研究将其它金属用于PEMFC阳极催化剂,但催化活性要比Pt低得多[1~4]。而Pt作PEMFC的阳极催化剂一个问题是痕量的CO,如10~100ppm就可以使Pt催化剂中毒[5,6]。现在的PEMFC一般用高压氢作为燃料,有很大的不安全性。人们提出用两种方法来解决这个问题,一是用甲醇、甲烷或汽油现场重整制氢作燃料的方法,但用这种制氢方法制得的氢气中含有大量的CO,即使经过纯化,也会含有ppm级的CO。另一个方法是直接用小分子醇类化合物,如甲醇作燃料,被称为直接醇燃料电池(DAFC)[7~11],但醇类化合物在阳极氧化时会有中间产物,如CO的产生,容易使阳极Pt催化剂中毒。因此,研究抗CO中毒的阳极催化剂已成为PEMFC和DAFC中一个很重要的研究课题。许多文章已报道Pt与其它贵金属或过渡金属的合金催化剂,或Pt与过渡金属氧化物的复合催化剂有一定的抗CO中毒能力。如Pt鄄Ru[12~16]、Pt鄄Bi[17]、Pt鄄Sn[17~19]...

Eu~(3+)和Ho~(3+)对乙醇在Pt-TiO_2/C电极上氧化的助催化作用

报道了用循环伏安法研究Eu3+和Ho3+吸附的碳载Pt-TiO2(pt-TiO2/C)催化剂对乙醇电化学氧化的助催化作用.发现无论在中性溶液中还是在酸性溶液中,当Pt-TiO2/C催化剂吸附Eu3+或Ho3+后,都可以使乙醇的电催化氧化电流密度明显增加,其原因主要是Eu3+或Ho3+都能促进吸附的CO的电氧化.

固相反应法合成Pt/MoO_3及其电催化作用

采用固相合成的方法制得直接甲醇燃料电池催化甲醇氧化的Pt/MoO3.XRD分析、循环伏安测试表明,Pt/MoO3对甲醇的氧化具有较好的催化作用,氧化峰电位出现在0.63V(vs.SCE),峰电流密度可达78.1mA·cm-2.

羰基簇合物途径制备的碳载Pt-Co催化剂阴极抗甲醇性能

通过Pt和Co羰基簇合物途径制备了碳载Pt Co(Pt Co/C)复合催化剂.其金属粒子的平均粒径小,相对结晶度很低.与商业化的E TEKPt/C催化剂相比,该催化剂具有较好的抗甲醇性能和电催化氧还原活性.

固相反应制备的Pt/C对甲酸氧化的电催化活性

研究了用固相反应法制备的碳载Pt(Pt/C(s) )催化剂对甲酸氧化的电催化活性 .XRD和TEM的测量表明 ,Pt/C(s)催化剂中Pt的平均粒径和结晶度远小于用传统的液相反应法制备的碳载Pt(Pt/C(l) )催化剂 ,因此 ,Pt/C(s)催化剂对甲酸氧化的电催化活性远高于Pt/C(l)催化剂.

Preparation of Pt/C catalyst with a new and simple organic sol method

It is reported for the first time that the Pt/C catalyst can be prepared with a new and simple organic sol method using SnCl2 as the reductant. It was found that the average size of the Pt particles in the Pt/C catalysts could be controlled with controlling the preparation conditions. The effect of the average sizes of the Pt particles in the Pt/C catalysts obtained with this method on the electrocatalytical activity of the oxidation of methanol was investigated.

Fabrication of core-shell Au-Pt nanoparticle film and its potential application as catalysis and SERS substrate

In this paper we report the rational design and fabrication of high-quality core-shell Au-Pt nanoparticle film. Such film shows highly efficient catalytic properties and excellent surface-enhanced Raman scattering (SERS) ability.

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.

Kinetics of atomic force microscope-based scanned probe oxidation on an octadecylated silicon(111) surface

Atomic force microscope (AFM)-based scanned probe oxidation (SPO) nanolithography has been carried out on an octadecyl-terminated Si(111) surface to create dot-array patterns under ambient conditions in contact mode. The kinetics investigations indicate that this SPO process involves three stages. Within the steadily growing stage, the height of oxide dots increases logarithmically with pulse duration and linearly with pulse voltage. The lateral size of oxide dots tends to vary in a similar way. Our experiments show that a direct-log kinetic model is more applicable than a power-of-time law model for the SPO process on an alkylated silicon in demonstrating the dependence of oxide thickness on voltage exposure time within a relatively wide range. In contrast with the SPO on the octodecysilated SiO2/silicon surface, this process can be realized by a lower voltage with a shorter exposure time, which will be of great benefit to the fabrication of integrated nanometer-sized electronic devices on silicon-based substrates. This study demonstrates that the alkylated silicon is a new promising substrate material for silicon-based nanolithography.