钛离子在铂阴极上电结晶形核过程的研究

本文应用循环伏安及计时电流暂态技术研究了低价钛离子在铂阴极上电沉积形核过程的规律。在LiCl-KCl低共晶体系中,温度为440～500℃、低价钛离子浓度为0.74～5.78wt％范围内,在铂阴极上以纯钛形式析出时存在明显的形核过程。其控制步骤是半球形晶核的形成,随后是钛离子向孤立的半球形晶核扩散控制下的晶核长大过程,且形核过程为瞬时形核。钛的晶核密度随阴极过电位、温度以及低价钛离子浓度的升高而增大。

示波极谱滴定的研究(ⅩⅩⅩⅦ)——双微铂电极示波极谱滴定的原理

本文对EDTA等试剂在双微铂电极示波极谱图上产生切口的原因进行了探讨。双微铂电极示波极谱图上EDTA的切口主要来源于EDTA在铂电极上的吸附,使氧在电极上的吸附过程受阻而降低了氧的还原电流,因而使每一个电极上的Ei~t曲线发生变形。双微铂电极上所得的E~t曲线是两个Ei^(t)曲线的叠加.因此在E^(t)曲线上出现了明显的折扭.在dE/dt^(E)曲线上出现切口。还解释了其它一些实验现象。

基于双向流固耦合的均压电极铂针力学性能研究

为研究换流阀设备水路中均压电极铂针在水流激励下的力学性能,利用CREO软件建立均压电极铂针流场的三维模型,将处理后的模型导入ANSYS Workbench平台,通过双向耦合模块将Fluent和Transient structural连接,并将数据传输接口定义在流固耦合界面上。考虑水流的周期波动特性,对离散后的有限元模型进行双向流固耦合下的瞬态分析,获得铂针的应力、应变动态响应曲线。通过对铂针进行力学性能试验得到其抗弯强度,得出结论:铂针在单端固定的方式下,其最大应力远小于材料抗弯强度,满足工程使用要求。

Influence of counter electrode material during accelerated durability test of non-precious metal electrocatalysts in acidic medium

Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be established for the reliable evaluation of NPMEs. In this study, platinum and graphite counter electrodes were used to investigate the impact of counter electrode material on the accelerated durability testing （ADT） of NPMEs in acidic medium. Platinum used as the coun- ter electrode in a traditional three-electrode electrochemical cell was found to dissolve in acidic medium and re-deposit on NPME coated on the working electrode during ADT. Such re-deposition causes the oxygen reduction reaction （ORR） performance of NPMEs to remarkably improve, and thus will seriously mislead our judgment of NPMEs if we are unaware of it. The phenomenon can be avoided using a graphite counter electrode.

Role of Bridge-bonded Formate in Formic Acid Dehydration to CO at Pt Electrode： Electrochemial in-situ Infrared Spectroscopic Study

Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.

Electroless Deposition of Nickel Nanowire and Nanotube Arrays as Supports for Pt-Pd Catalyst for Ethanol Electrooxidation

Nickel nanowire and nanotube arrays as supports for Pt-Pd catalyst were prepared by elec- troless deposition with anodic aluminum oxide template. Pt-Pd composite catalyst was de- posited on the arrays by displacement reaction. SEM images show that the nickel nanowires have an average diameter of I00 nm and the nickel nanotubes have an average inner diameter of 200 nm. EDS scanning reveals that elemental Pt and Pd disperse uniformly on the arrays. Cyclic voltammetry study indicates that the nickel nanotube array loaded with Pt-Pd pos- sesses a higher electrochemical activity for ethanol oxidation than the nickel nanowire array with Pt-Pd.

Mechanistic insight into methanol electro‐oxidation catalyzed by PtCu alloy

In this work,we have performed density functional theory(DFT)calculations to investigate the methanol electro‐oxidation reaction(MOR)catalyzed by the Pt,PtCu alloy and Cu.The complex reaction networks,including the intermediate dehydrogenation,water dissociation and anti‐poison reaction steps,are systematically investigated to explore the mechanisms.At the standard condition of pH=0 and zero potential,for Cu,most dehydrogenation steps along the favorable pathway are endergonic,making it less active in MOR.For the Pt and PtCu alloy,their dehydrogenation steps are mainly exergonic,but the formed CO intermediate binds too tightly on Pt,that can accumulate on active sites to poison the electro‐catalyst.The CO can be consumed by the thermodynamic reaction with OH*,which comes from water dissociation.DFT calculation shows alloying the Pt with Cu could not only reduce the free energy barrier for binding between CO*and OH*,but also assist the water dissociation to produce more OH*for that anti‐poison reaction.That makes the PtCu alloy more active than the pure Pt electrode in experiment.The results reveal the importance of anti‐poison reaction and water dissociation in MOR,which could be applied to the rational design of more active alloy electro‐catalysts in future.

Preliminary study on electrochemical reduction of carbon dioxide on nickel and platinum electrodes

The electrochemical reduction of carbon dioxide was investigated on nickel and platinum electrodes in 0.5 mol dm^-3 KHCO3 solutions. The main products were formic acid and carbon monoxide during the electroreduction of CO2, and the Faradaic efficiency for this process depended on the characteristics of the electrode. At ambient temperature and pressure, the Faradaic efficiency was measured to be 8.6% and 2.5 % respectively for the production of formic acid and CO with Pt electrode at - 1.3V vs Ag/AgCl （saturated KCl）. At this same potential, the Faradaic efficiency was measured to be 8.9% and 1.7% respectively with Ni electrode. Tafel plots showed that the electrochemical reduction of CO2 was not limited by the mass transfer process in the range of -0.8 to - 1.2V vs Ag/AgCl （saturated KCl）.

Use of microelectrodes for electrochemical measurement of nitric oxide in natural seawater

In this paper, the application of a homemade Nafion and Co(Salen) modified platinum microelec-trode and an ISO-NOPMC microsensor (World Precision Instruments, USA ) to measure nitric oxide in natural seawater is reported. These two microelectrodes are suitable for the measurement. In natural seawater, the sensitivity and stability of the ISO-NOPMC microsensor are higher than that of the homemade Nafion and Co(Salen) modified platinum microelectrode.

Hydrogen Adsorption on Pt, Rh and Pt-Rh Electrodes

The hydrogen adsorption on Pt-Rh alloys in sulfuric acid aqueous solutions was studied by the method of cathode pulses. Hydrogen adsorption on the electrode with all ratio of alloy components (ωRh = 0-100%) is well described by the Temkin logarithmic isotherm. The surface coverage by adsorbed hydrogen at the same potential is decreased with increasing content of rhodium in the system. A linear dependence of adsorption peak potential on the alloy compositions in the case of weakly bonded adsorbed hydrogen is established. Hydrogen adsorption heat as a function of surface coverage for Pt-Rh-electrodes was obtained. The shape of the current-potential curve and position of the weakly bonded hydrogen adsorption on the potential scale are all related to alloy compositions, thus can serve as the basis for the determination surface composition of alloys.

Ion-Conductive-Polymer-Film Actuators with Pt Electrodes Selectively Grown using Non-Electrolyzed Plating

Organic soft actuators are of special interest in many fields including intravascular neurosurgery. Ion conductive polymer film （ICPF） actuators have been one of the strong candidates. The ICPF investigated here was a cation-exchange membrane （Nation 117, Du Pont）. When a voltage is given between the metal eIectrodes of an ICPF actuator, the ICPF actuator bends in the water due to the motion of Li＋ cations with associated water. In order to increase the freedom of the deformation of the ICPF actuator, structures of independent electrode pairs were proposed. The electrodes were selectively deposited by non-electrokvzed plating including the Pt [（NH3）6]^4＋ deposition process in a [Pt（NH3）6]Cl4 solution and the reduction process in a NaBH4 solution. Here, an elastomer adhesive tape with a fine electrode patterns was used performances were reported in detail. as a mask. The actuators processing conditions and their actuator

Anodic Alumina Supported Pt Catalyst for Total Oxidation of Trace Toluene

Featuring an assembly of identical pores, through-pore anodic alumina （AAO） makes an ideal monolith-like cat- alyst support for volatile organic compound （VOC） combustion. This work employs the oxidation of toluene as a model reaction to investigate the applicability of AAO supported Pt catalysts in VOC catalytic combustion. In order to modify the microstructure of AAO, some AAO samples were exposed to hot water treatment （HWT） firstly. Re- sults show that the optimum HWT time is 18 h. Pt/HWT18 gives a toluene conversion of95%; at 200 ℃, which is comparable to the initial activity of commercial γ-A1203 particle supported Pt catalyst. Considering its confine- ment effect for the supported metal and its monolith-like compact unit, AAO support offers potential applications in VOC catalytic combustion.

Mechanism for nucleation and growth of electrochemical deposition of palladium(II) on a platinum electrode in hydrochloric acid solution

Palladium（II） and chloride ions tend to form complexes in aqueous solution. Both theoretical and experimental （by UV spec- trum） results indicate that there are four complexes formed in aqueous solution containing 3 mol/L hydrochloric acid and 20 mmol/L PdC12. This work evaluates the kinetics of electrochemical deposition of palladium on a Platinum electrode. For this purpose, palladium electrodeposition was investigated by means of cyclic voltammetry （CV）, potentiostatic current-time tran- sients （CTTs） and Tafel curve. By CTTs curves, the regions corresponding to the charge transfer control, mixed control and diffusion control were identified. In the diffusion control region, palladium electrodeposition mechanism was characterized as progressive nucleation with three-dimensional （3D） growth under diffusion control; as for the mixed control region, an adsorp- tion （1Ads）, ion transfer （liT）, and nucleation and growth （ING） model were proposed to analyze the current-time transients quan- titatively, which could separate the IAds, lit and IN~ perfectly.

Ternary PtRuTe alloy nanofibers as an efficient and durable electrocatalyst for hydrogen oxidation reaction in alkaline media

Sluggish kinetics of anodic hydrogen oxidation reaction(HOR)in alkaline media,which arises from the two orders of magnitude lower HOR activity in alkali than that in acid media for platinum group metals,hinders the commercial implementation of anion exchange membrane fuel cells(AEMFCs).Consequently,the development of platinum-based catalysts combined with high efficiency and durability is urgently required.Herein,we report a facile route for the synthesis of ternary PtRuTe alloy nanofibers with Pt atomic ratio of only 11%via a simple galvanic replacement reaction.We optimize the adsorption strength of platinum and ruthenium towards hydrogen and hydroxyl species by regulating the electron donation from tellurium to platinum and ruthenium.Hence,the obtained trimetallic alloy catalyst exhibits an impressive kinetic current density of 30.6 mA cm^(−2)_(geo) at 50 mV and an exchange current density of 0.426 mA cm^(−2)_(metal),which shows 3.0-and 2.5-fold enhancement compared with the commercial Pt/C in alkaline electrolyte,respectively.Moreover,the catalyst also demonstrates excellent stability with merely 5%activity attenuation after 2000 potential cycles.This work offers new pathways to boost alkaline HOR by rationally designing multicomponent alloys.

Investigation of flexible electrodes modified by TiN,Pt black and IrO_x

TiN, platinum （Pt） black and iridium oxide are introduced to the stimulating sites to improve the performance of the flexible electrode. Low temperature process is used to fabricate the modifying films. TiN is coated on the gold sites by magnetron sputtering while platinum black and iridium oxide are coated by electroplating and electrodeposifion, respectively. The impedance of the electrode decreases dramatically after modification. The combined analysis of surface morphology and cyclic voltammograms （CV） in phosphate buffer saline （PBS） solution indicates that the modified electrode sites have larger electrode-electrolyte capacitance and smaller faradic resistance than unmodified sites, thus they have smaller electrochemical impedances.

A glucose biosensor based on direct electrochemistry of glucose oxidase immobilized onto platinum nanoparticles modified graphene electrode

The platinum nanoparticles were adsorbed on graphene oxide sheets and played an important role in catalytic reduction of graphene oxide with hydrazine, leading to the formation of graphene-Pt nanoparticles. Because of their good electronic properties, biocompatibility and high surface area, graphene-Pt based composites achieved the direct electron transfer of redox enzyme and maintained their bioactivity well. The graphene-Pt nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED). The amperometric biosensor fabricated by depositing glucose oxidase over Nafion-solubilized graphene-Pt electrode retained its biocatalytic activity and has offered fast and sensitive glucose quantification.

关于提前工业电快报报送日期的—些体会

1958年2月份的工业电快报和计划执行情况分析报告我们于3月2日夜12时做完,3日一清早就送到国家统计局和本市各党政领导机关,比国家统计局原规定的报送日期提前了4天.

旅大市的物资统计在工业“抗旱”运动中发挥了巨大作用

旅大市开展了一个工业“抗旱”运动,发动群众千方百计挖掘钢铁材料,解决在生产跃进形势下出现的原材料供应不足的困难.在这次中心运动中,我们统计部门不是站在运动之外,而是积级主动地投入运动的洪流中去,把统计任务统盘担当起来,为具有重大政治经济意义的工业“抗旱”运动服务.