Blocking the defect sites on ultrathin Pt nanowires with Rh atoms to optimize the reaction path toward alcohol fuel oxidation

Anodic electrocatalyst plays the co re role in direct alcohol fuel cells(DAFCs),while traditional Pt-catalysts suffer from limited catalytic activity,high over potential and severe CO poisoning.Herein,by selectively depositing Rh atoms on the defective-sites of Pt nanowires(NWs),we developed a new Pt@Rh NW electrocatalyst that exhibited enhanced electrocatalytic performance for both methanol oxidation(MOR)and ethanol oxidation(EOR).Both cyclic voltammetry(CV) and in-situ infrared spectroscopy re...     

STUDY ON ELECTROOXIDATION OF TRACE CO(Ⅰ) REACTION KINETICS ON Pt/C CATALYST

We have determined experimentally the reaction kinetics of the electrocatalytic oxidation of the trace carbon monoxide on Pt/C catalyst in aqueous sulphuric acid.At the constant potential 0.947V vs.NHE,the overall rate equation may be expressed bywhere y is a parameter relating to the concentration of H3O .Assuming that the rate of the electrocatalytic oxidation of carbon monoxide is controlled by the edectrochemical reaction of the adsorbed CO and adsorbed OH and that t the surface of catalyst is homogeneous,we can obtain a theoretical rate equation which is formally the same as the empirical rate equation.Recently,instruments for monitoring trace toxic gases in atomosphere based on electrochemical principles have been reported The determinable gases may involve CO,SO2H2S,nitrogen oxides,various gaseous paraffins,and so on.This new method raises wide interests for its many cdvantages,for instance,the price is cheap: the operation is simple and it can be used directly to monitor atmospheric toxic gases     

Electrocatalytic Oxidation of Formic Acid by Polyaniline-Poly （ Propylene Oxide）

Formic acid is a liquid fuel for the direct formicacid fuel cell (DFAFC), which has a high theoretical open circuit potential and is an attractive alternativefor portable power devices. In the past, the research of the electrochemical behavior of formic acid was limited to Pt, Pt/Pd or Pt/Ru. Many studies have shown that the electrocatalytic oxidation rate of formic acid on a pure Pt electrode is insufficient for DFAFC.     

Studies of surface processes of electrocatalytic reduction of CO<Subscript>2</Subscript> on Pt(210), Pt(310) and Pt(510)

Surface processes of CO2 reduction on Pt(210), Pt(310), and Pt(510) electrodes were studied by cyclic voltammetry. Different surface structures of these platinum single crystal electrodes were obtained by various treatment conditions. The experimental results illustrated that the electrocatalytic activity of Pt single crystal electrodes towards CO2 reduction is decreased in an order of Pt(210)＞Pt(310)＞Pt(510), i.e., with the decrease of (110) step density on well-defined surfaces. When the surfaces were reconstructed due to oxygen adsorption, the catalytic activity of all the three electrodes has been enhanced to a certain extent. Although the activity order remains unchanged, the electrocatalytic activity has been enhanced more significantly as the density of (110) step sites is more intensive on the Pt single crystal surface. It has revealed that the more open the surface structure is, the more active the Pt single crystal electrode will be, and the easier for the electrode to be transformed into a surface structure that exhibits higher activity under external inductions. However, the relatively ordered surfaces of Pt single crystal electrode are comparatively stable under the same external inductions. The present study has gained knowledge on the interaction between CO2 and Pt single crystal electrode surfaces at a microscopic level, and thrown new insight into understanding the surface processes of electrocatalytic reduction of CO2.     

Electrochemical Oxidation of Ammonia on Ir Anode in Potential Fixed Electrochemical Sensor

Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH3 and NH4OH in a NaClO4 solution, NH4OH can be used instead of NH3 for the experimental convenience. It was found that the potential of the oxidation peak of NH4OH at the Ir/GC electrode in NaClO4 solutions is at about 0.85 V, and the current density of the oxidation peak of NH4OH is linearly proportional to the concentration of NHaOH. The electrocatalytic oxidation of NH4OH is diffusion-controlled. Especially, Ir has no electrocatalytic activity for the CO oxidation, illustrating that CO does not interfere in the measurement of NH4OH and the potential fixed electrochemical NH3 sensor with the neutral solution, and the anodic Ir catalyst possesses a good selectivity. Therefore, Ir may have practical application in the potential fixed electrochemical NH3 sensor with the neutral solution.     

Preparation of Pt／C Catalyst with Solid Phase Reaction Method

The Pt/C catalyst was prepared with solid phase reaction method (Pt/C(S)) for the first time.Its Performances were compared with that prepared by the traditional liquid phase reaction method. The results demonstrate that the electrocatalytic activity of Pt/C catalyst with solid phase reaction method for methanol oxidation is higher than that with liquid phase reaction method. XRD and TEM measurements indicate that the Pt/C(S) possesses low crystalline extent and small particle size.     

Studies of surface processes of electrocatalytic reduction of CO_2 on Pt(210), Pt(310) and Pt(510)

Surface processes of CO2 reduction on Pt(210), Pt(310), and Pt(510) electrodes were studied by cyclic voltammetry. Different surface structures of these platinum single crystal electrodes were obtained by various treatment conditions. The experimental results illustrated that the electrocatalytic activity of Pt single crystal electrodes towards CO2 reduction is decreased in an order of Pt(210)>Pt(310)>Pt(510), i.e., with the decrease of (110) step density on well-defined surfaces. When the surfaces were reconstructed due to oxygen adsorption, the catalytic activity of all the three electrodes has been enhanced to a cer- tain extent. Although the activity order remains unchanged, the electrocatalytic activity has been en- hanced more significantly as the density of (110) step sites is more intensive on the Pt single crystal surface. It has revealed that the more open the surface structure is, the more active the Pt single crystal electrode will be, and the easier for the electrode to be transformed into a surface structure that exhib- its higher activity under external inductions. However, the relatively ordered surfaces of Pt single crystal electrode are comparatively stable under the same external inductions. The present study has gained knowledge on the interaction between CO2 and Pt single crystal electrode surfaces at a micro- scopic level, and thrown new insight into understanding the surface processes of electrocatalytic re- duction of CO2.     

2D Bi2WO6/MoS2 as a new photo-activated carrier for boosting electrocatalytic methanol oxidation with visible light illumination

A kind of new 2D heterojunction of Bi₂WO₆/MoS₂ was constructed and used as visible-light activated carrier for depositing Pt electrocatalyst. With assistance of visible light irradiation, Pt-Bi₂WO₆/MoS₂ composite shows enhanced electrocatalytic activity and stability towards methanol oxidation than traditional electrocatalytic process and commercial Pt/C.     

Electrochemical characterization of MnO2 as electrocatalytic energy material for fuel cell electrode

 Development of inexpensive non Pt based high electrocatalytic energy materials is the need of the hour for fuel cell electrode to produce clean alternative green energy from synthesized bio alcohol using biomass. MnO₂, electro synthesized at different current density is found to be well performed electrocatalytic material, comparable to Pt, with higher current density, very low overvoltage for the electrochemical oxidation of methanol. From EIS study, the polarization resistance of the coated MnO₂ is found to be much low and electrical double layer capacitance is high, the effect increases with increase in current density of electro deposition. XRD, EDX and AAS analysis confirm the MnO₂ deposition. The morphology of SEM images exhibits an enhanced 3D effective substrate area, for electro oxidation of the fuel. A few nano structured grains of the deposited MnO₂ is also observed at higher current density. The fact supports that a high energetic inexpensive electro catalytic material has been found for fuel cell electrode to synthesis renewable energy from methanol fuel.     

Pt/十六烷基三甲基溴化铵纳米聚集体修饰玻碳电极促进析氢(英文)

A novel, cost‐effective, and simple electrocatalyst based on a Pt‐modified glassy carbon electrode (GCE), using cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, is reported. Am‐phiphilic CTAB molecules were adsorbed on GCE by immersion in a CTAB solution. The positively charged hydrophilic layer, which consisted of small aggregates of average size less than 100 nm, was used for accumulation and complexation of [PtCl6]2? anions by immersing the electrode in K2PtCl6 solution. The modified electrode was characterized using scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, impedance spectroscopy, and electrochemical methods. The electrocatalytic activity of the Pt particles in the hydrogen evolution reaction (HER) was investigat‐ed. The results show that the CTAB surfactant enhances the electrocatalytic activity of the Pt parti‐cles in the HER in acidic solution.     

Electrooxidation of 2-propanol on Pt, Pd and Au in alkaline medium

Pd and Au are investigated as electrocatalysts for 2-propanol oxidation and compared with the conventional catalyst of Pt in alkaline medium. The current density for 2-propanol oxidation on Pd electrode is much higher than that on Pt electrode. The onset potential for 2-propanol oxidation on Pd electrode is more negative compared with that on Pt electrode. The results show that Pd is a good electrocatalyst for 2-propanol oxidation and the activity for the electrooxidation of 2-propanol is higher than Pt and Au in alkaline medium. Pd has higher electrocatalytic activity and better stability for the electrooxidation of 2-propanol. The present study shows a promising choice of Pd as effective electrocatalyst for 2-propanol electrooxidation in alkaline medium.     

片层WC/C的原位合成及其在甲醇氧化中的应用

以片层二硫化钨(WS2)为前驱体,氯化钠(Na Cl)为介质,CO为气体碳源,采用程序升温法一步合成片层碳化钨/碳复合材料(WC/C)。通过X射线衍射(XRD),X射线近边吸收谱(XANES)和扫描电镜(SEM)等一系列手段对样品的化学组成、形貌、结构等进行表征。研究发现,在高温渗碳过程中,不仅利用WS2的片层结构和Na Cl的锚定作用合成了具有薄层孔洞的WC,而且Na Cl和WS2金属面对碳膜生长的催化作用使WC表面覆有原位生长的碳膜,为电子传输提供了有效通道。将该材料作为载体材料进行电化学性能测试,结果表明:负载少量Pt后制得的Pt/WC/C电催化剂,在甲醇氧化反应(MOR)中表现出良好的电催化活性、稳定性及优异的抗CO中毒能力。     

Pt/RuO2/CNTs纳米催化剂中RuO2含量对甲醇电催化氧化性能的影响

制备了一种新的甲醇直接燃料电池Pt/RuO2/CNTs阳极催化剂,在相同Pt负载量下,其甲醇电催化氧化活性是Pt/CNTs的3倍.采用循环伏安法研究发现Pt/RuO2/CNTs纳米催化剂中RuO2含量对甲醇电催化氧化活性有明显影响,当Pt和RuO2在碳纳米管上含量分别为15%和9.5%时,Pt/RuO2/CNTs催化剂具有最佳的甲醇电催化氧化活性.RuO2负载在碳纳米管上比电容的变化,反映了水合RuO2结构中质子与电子传输平衡的能力,分析表明,催化剂中RuO2含量不同导致电容的变化是影响甲醇电催化氧化活性的主要原因.当催化剂结构中质子与电子传输达到平衡时,催化剂比电容最大,电催化氧化活性最高.这种基于电容关联电催化剂的观点对甲醇直接燃料电池阳极催化剂的设计非常有意义.     

Au nanowires with high aspect ratio and atomic shell of Pt-Ru alloy for enhanced methanol oxidation reaction

The methanol oxidation reaction(MOR) is the limiting half-reaction in direct methanol fuel cell(DMFC).Although Pt is the most active single-metal electrocatalyst for MOR,it is hampered by high cost and CO poisoning.Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited(UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning.Herein,we prepared one-dimensional surface-alloyed electrocatalyst from predominantly(111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition.The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru.Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR.Among all these catalysts,Au@Pt_(ML)@Ru_(ML) exhibits the best electrocatalytic activity and poisoning tolerance to CO.This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.     

“卡房”结构LDHs负载Pt纳米催化剂用于乙醇电催化氧化

乙醇电催化氧化是直接乙醇燃料电池(DEFCs)的核心反应,而DEFCs的阳极电催化剂是提升乙醇转化效率的关键。Pt作为最稳定、最有效的催化剂之一,仍面临着成本高、容易被乙醇氧化产生的中间产物毒化等问题。选择合适的载体实现Pt的高度、均匀、稳定分散,不仅可以提高其抗中毒能力和催化活性,而且还可以减少Pt用量降低成本。本文采用两步电化学沉积法合成了层状双金属氢氧化物(LDHs)纳米阵列负载Pt纳米催化剂(Pt/LDHs/NF),具有“卡房”结构的LDHs增强了Pt纳米粒子的分散,有助于实现高效的乙醇电催化氧化性能。制备的Pt/NiFe-LDH/NF在碱性环境下对乙醇表现出最优的电催化氧化活性,峰值电流密度达到171.99mA·cm^-2。这可为今后设计和制备均匀、稳定分散的Pt基催化剂用于乙醇电催化氧化提供借鉴。     

PEMFC催化剂的研究：自制抗CO中毒Pt-Ru/C电催化剂的性质

用胶体法制备了抗CO中毒PEMFC阳极Pt-Ru/C电催化剂（标记为THYT－2）,对 比研究了THYT－2与Johnson Matthey (JM)公司同类品牌Pt-Ru/C催化剂的电化学及 其它物理化学性能。结果表明,THYT－2电催化剂在甲醇燃料电池和CO／H_2（Φ_ (CO) = 1 * 10~(-4)）的氢氧燃料电池中的电催化行为与JM催化剂相当,但THYT－ 2在低浓度CO氢气燃料中的电池性能更好。两种催化剂的其它物理化学性质具有类 似性：XPS分析结果表明THYT－2和JM催化剂 中都有三种不同价态的Pt存在：即金 属态Pt(0)、氧化态Pt(II)和Pt(IV)。HRTEM测试结果表明两种催化剂的粒径处在2 ～3 mn左右,这可能是它们拥有良好电化学性能的主要原因之一。本文还对催化剂 中Pt与Ru组分的分布和相互作用进行了讨论,提出了改进Pt-Ru/C电催化剂的思路 。     

Pt-Mo电极上CO、甲醛和甲醇的电催化氧化-微分电化学质谱研究

利用微分电化学质谱（DEMS）研究了Mo修饰的Pt电极上CO、甲醛和甲醇的电催 化氧化,证实了Mo(IV)是催化活性样品,而且它只对弱吸附CO的氧化起催化作用, 对强吸附CO的氧化没有催化活性。在低于0.4 V的电位下,吸附在Pt电极上的Mo结 甲醇和甲醛的催化氧化是通过弱吸附CO的氧化路径进行的。     

Single‐Molecule Nanocatalysis Shows In Situ Deactivation of Pt/C Electrocatalysts during the Hydrogen‐Oxidation Reaction

By coupling a Pt‐catalyzed fluorogenic reaction with the Pt‐electrocatalyzed hydrogen‐oxidation reaction (HOR), we combine single‐molecule fluorescence microscopy with traditional electrochemical methods to study the real‐time deactivation kinetics of a Pt/C electrocatalyst at single‐particle level during electrocatalytic hydrogen‐oxidation reaction. The decay of the catalytic performance of Pt/C could be mainly attributed to the electrocatalysis‐induced etching or dissolution of Pt nanoparticles. Spontaneous regeneration of activity and incubation period of the Pt electrocatalyst were also observed at single‐particle level. All these new insights are practically useful for the understanding and rational design of highly efficient electrocatalysts for application in fuel cells.     

一种提高铂电催化氧化甲酸性能的简单方法

在离子液体1-乙基咪唑三氟乙酸盐(HElmTfa)中,采用循环伏安法在铂电极表面修饰聚吡咯(PPY),制得PPy-HEImTfa/Pt,并研究了其对甲酸的电催化氧化性能.与相同条件下的铂基底电极相比,PPy-HEImTfa/Pt对甲酸的电催化氧化性能有很大的提高.原位红外光谱表明,PPy-HElmTfa能降低中间体CO等对铂电极的毒化作用,促进甲酸直接氧化生成CO_2.