Effect of Specific Adsorption of Anions and Surface Structure of Pt(111) Electrode on Kinetics of Dissociative Adsorption of Ethylene Glycol

运用电化学循环伏安和程序电位阶跃方法研究了阴离子特性吸附和PT(111)电极表面结构对乙二醇解离吸附反应动力学的影响.结果表明,阴离子特性吸附显著影响乙二醇的解离吸附,在高氯酸介质中(无特性吸附)测得乙二醇解离吸附反应的初始速率VI以及解离吸附物种(dA)的饱和覆盖度均明显大于硫酸溶液(发生SO24-/HSO4-特性吸附)中的相应值;其平均速率V随电极电位的变化呈类似火山型分布,最大值位于0.22V(VSSCE)附近.还发现通过不同处理获得的PT(111)电极的不同表面结构对这一表面过程也具有显著的影响.The effect of specific adsorption of anions and the surface structure of a Pt(111) electrode on the kinetics of dissociative adsorption of ethylene glycol (EG) was studied using cyclic voltammetry and a programmed potential step technique.Quantitative results demonstrated that the specific adsorption of anions remarkably influenced the dissociative adsorption of EG.Both the initial reaction rate (vi) of the EG dissociative adsorption and the saturated coverage of dissociative adsorbates, measured in perchloric acid media (without specific adsorption), are significantly larger than the corresponding values acquired in sulfuric acid media (with specific adsorption of SO420-/HSO4-).We illustrate that the variation of the average reaction rate v of EG dissociative adsorption on Pt(111) in perchloric acid media with an electrode potential yields a volcano-like distribution with a maximum value near 0.22 V (vs SCE).Furthermore, different surface structures of the Pt(111) electrode that were obtained by different treatments also significantly affect this surface process.国家自然科学基金(20673091;20833005);广西师范大学博士科研启动基金资

Mechanism of Functional Molecules in Shape-Control Synthesis of Noble Metal Nanocrystal Catalysts

金属纳米晶催化剂(简称金属纳米催化剂)广泛应用于化学、能源等现代工业。铂等稀贵金属目前仍然是燃料电池等领域不可替代的催化剂材料,进一步提高金属催化剂的性能和利用率一直是重大挑战。金属的表面结构取决于晶体的形状。因此,形状控制合成可有效地调控金属纳米晶催化剂的表面结构和性质,近年来得到了大量研究。功能分子(保护剂、稳定剂、表面活性剂、添加剂等)对金属纳米晶的形状控制合成具有重要作用,尤其是在湿化学法形状控制合成中。深入认识功能分子在形状控制合成中的作用机理,可为理性地设计和制备具有特定功能的纳米催化剂提供指导。功能分子通常是通过在纳米晶核特定晶面上优先吸附,或刻蚀某些特定的晶面,或者加速或抑制某些晶面的生长实现对纳米晶催化剂表面结构的调控。虽然通过结构控制合成的电化学法和湿化学法已经制备出大量不同表面结构的金属纳米晶催化剂,但是对功能分子作用机理的认识还远未深入。本文综述了近二十年金属纳米晶催化剂形状控制合成的进展,侧重阐述对功能分子作用机理的研究,总结了功能分子在金属纳米晶催化剂形状控制合成中优先吸附的重要作用机制,以及优化功能分子在纳米粒子形状控制合成中的一些基本策略。Metal nanocrystal catalysts(abr.metal nanocatalysts) are widely used in chemical and energy industries.The rare and precious metals as platinum are actually irreplaceable materials for catalysts,therefore to improve the activity and utilization efficiency of metal catalysts is always a challenge.Shape-control synthesis is an efficient way to tailor the surface structure of metal nanocrystal and therefore create particular functions in catalysis.The functional molecules such as stabilizers,capping agents,surfactants and additives,etc.,are indispensable in the shape-control synthesis,especially in the wet chemistry route.In order to rationally design and synthesize metal nanocatalysts with high activity,high selectivity and high stability,it is important to explicit the roles and mechanisms of functional agents in shape-control synthesis.The functional agents usually assist in shape-control synthesis of nanocrystals through preferential adsorption on specific crystal facets,or etching particular crystal planes,or accelerating / inhibiting certain crystal growth directions.Although a mass body of metal nanocrystals with different shape have been synthesized,the explicit roles and mechanism of functional molecules in the shape-control synthesis are poorly defined and a full understanding is still elusive.The current paper reviews mainly the recent progress made in studies of mechanism of functional molecules in shape-control synthesis of metal nanocatalysts in the last two decades.The mechanism of preferential adsorption of functional agents and some basic strategy of optimizing the use of functional molecules in shape control synthesis of noble metal nanocatalysts are summarized.国家自然科学基金“界面电化学”创新研究群体项目(No.21021002)资

Effects of Low Energy Carbon Ion and Nitrogen Ion Implantation on Germinant Rate, Growth Weight and Peroxidase of Stevia rebaudiana Bertoni

以经过碳、氮 (75× 1 0 14 ke V/ cm2 )离子注入处理后的甜叶菊 (Stevia rebaudianaBertoni)种子为材料 ,研究低能离子注入对甜叶菊萌发率、生长量及过氧化物同工酶的影响。结果表明 :(1 )萌发期处理组的萌发率低于对照 ,萌发延迟 ,幼苗成活率不及对照组 ;萌发后期处理组的相对生长量、过氧化物酶活性高于对照组。 (2 )幼苗移至实验地种植后 ,处理组幼苗长势明显优于未处理组 ,处理组 60 d蕾株比明显高于对照组。 (3)过氧化物酶同工酶谱分析发现 ,对照组具有完整 6条基本带的植株数为 1 2 ,具有完整 B1、B2基本带的植株数为 2 0 ;C+处理组分别为 5和 1 1 ,N+处理组分别为 5和 6。统计发现低能离子的注入影响最大的是同工酶谱 B1、B2带。 N+处理组生物学负效应大于 C+处理组The paper reports the effects of low energy Carbon and Nitrogen ion (75×10 14 keV/cm 2 )implantation into S. rebaudiana seeds.on germinant rate, relative growth weight and peroxidase of S. rebaudiana. The results showed: (1)The seed germinant rates were lower and seeding servival rates and deve lopment speeds were slower in the treated groups than those in the control in the initial period of seed germinating;but in the late period of seed germinating the relative growth weight and peroxidase activity were higher in treated groups than those in the control.(2)When seedings were transplanted into experimental field the growth and development were speeded up in treated groups than that in the control.The rate of flower bud plants were higher in treated groups than that in the control. (3)The isozymogram of peroxidase by PAGE showed that there were 12 plants which had 1～6 basic bands and 20 plants which had B1,B2 bands in the control,but only there were 5 plants and 11 plants, respectively, in C + treated groups,and there were 5 plants and 6 plants, respectively, in N + treated groups. The result also showed there were more negative effects by ion implantation into S. rebaudiana in N + treated groups than those in C + treated groups in the periods of seed germinating and plant growth.国家基金委重大项目资助课题!( 1 9890 30 0

Large Scale Numerical Simulations For Multi-Phase Fluid Dynamics With Moving Interfaces

This short communication presents our recent studies to implement numerical simulations for multi-phase flows on top-ranked supercomputer systems with distributed memory architecture. The numerical model is designed so as to make full use of the capacity of the hardware. Satisfactory scalability in terms of both the parallel speed-up rate and the size of the problem has been obtained on two high rank systems with massively parallel processors, the Earth Simulator (Earth simulator research center, Yokohama Kanagawa, Japan) and the TSUBAME (Tokyo Institute of Technology, Tokyo, Japan) supercomputers

Electrochemical behavior of p-dihydroxybenzene in DMPC biomimetic membrane

在金电极上构筑一种双肉豆蔻磷脂酰胆碱(DMPC)仿生浇铸膜。经椭圆偏振仪和电化学方法测量证实, DMPC仿生膜是较为致密的多层膜,同时对苯二酚能够透过DMPC仿生膜到达金电极表面进行氧化反应。结果表明,对苯二酚不仅可在脂质膜中进行电子转移,而且是一种重要的生物分子。反应在仿生环境内进行,也为研究生物小分子在真正的生物体内的反应提供有益的帮助。本文探讨对苯二酚在仿生膜修饰电极上的电化学行为,为生物膜中的电子转移过程提供了十分重要的信息。The casting method to form dimyristoyl phosphatidyl choline(DMPC)mimetic biomembrane on an Au electrode is proposed.The results of ellipsometer and electrochemical methods confirmed that the film is a compact membrane that can block the electron transferring process,p-Dihydroxybenzene can reach the electrode surface and occur redox reactions by passing through transient defects in individual bilayers.Such defects occur in biomembranes and are accentuated by relatively small electric fields.The electrochemical behavior of p-dihydroxybenzene in this membrane was also investigated,p-Dihydroxybenzene is biologically important molecule because of its function of transferring electrons in lipid layers.This reaction occur in the bionic environment,which provide the useful help to study the real reaction of small molecules in the biological organisms.Studies on the electrochemical behavior of p-dihydroxybenzene in the DMPC biomimetic membrane provide useful information for elucidating biological electron transfer processes concerning lipid layers.国家自然科学基金项目(20833005,20873116)。~

Pt(100)电极上乙二醇吸附和氧化的原位时间分辨FTIRS研究

运用原位时间分辨FTIR反射光谱在分子水平研究乙二醇(EG)在Pt(100)单晶电极上吸附和氧化的动力学过程.在0.10V的时间分辨光谱中,当t>5s于2050cm?1附近出现的红外谱峰归因于EG解离吸附产物线性吸附态CO(COL)的红外吸收.红外光谱特征及其变化还证实,吸附态CO在Pt(100)表面呈均匀分布;当t>70s于2342cm?1附近出现CO2的不对称伸缩振动谱峰,指认为EG的直接氧化.研究发现随着电位升高,直接氧化逐渐成为主要反应途径,使解离吸附反应削弱.当电位高于0.40V以后,EG的氧化主要通过活性中间产物(–COOH)的途径进行

In situ time-resolved FTIRS study of adsorption and oxidation of ethylene glycol on Pt(100) electrode

Adsorption and oxidation of ethylene glycol (EG) on Pt(100) electrode were studied by in situ time-resolved FTIRS (TRFTIRS). The TRFTIR spectra recorded at 0.10 V illustrate that an IR band appears near 2050 cm(-1) at t > 5 s, corresponding to linearly bonded CO formed in dissociative adsorption of EG The TRFTIR results have confirmed also that CO species are distributed uniformly on Pt(100) surface. Another band appears near 2342 cm(-1) at t < 70 s, associating with IR absorption of CO2 produced in the direct oxidation of EG With the increase of electrode potential, the direct oxidation of EG becomes gradually the main reaction. When the potential is above 0.40 V, the oxidation of EG occurs mainly via the reactive intermediates, i.e. species containing -COOH determined by in situ TRFTIRS

Effect of Specific Adsorption of Anions and Surface Structure of Pt(111) Electrode on Kinetics of Dissociative Adsorption of Ethylene Glycol

The effect of specific adsorption of anions and the surface structure of a Pt(111) electrode on the kinetics of dissociative adsorption of ethylene glycol (EG) was studied using cyclic voltammetry and a programmed potential step technique. Quantitative results demonstrated that the specific adsorption of anions remarkably influenced the dissociative adsorption of EG. Both the initial reaction rate (v(i)) of the EG dissociative adsorption and the saturated coverage of dissociative adsorbates, measured in perchloric acid media (without specific adsorption), are significantly larger than the corresponding values acquired in sulfuric acid media (with specific adsorption of SO42-/HSO4-). We illustrate that the variation of the average reaction rate (v) over bar of EG dissociative adsorption on Pt(111) in perchloric acid media with an electrode potential yields a volcano-like distribution with a maximum value near 0.22 V (vs SCE). Furthermore, different surface structures of the Pt(111) electrode that were obtained by different treatments also significantly affect this surface process

Determination of Trace Metal Elements in Crude Oils by Microwave Digestion-Inductively Coupled Plasma-Mass Spectrometry Assisted with Organic Solvent

李景喜( 1980 － ) ，男，山东临沂市人，研究实习员，从事分析化学研究。E-mail: jxli@fio．org． cn。[中文摘要]建立了二氯甲烷溶剂辅助微波消解-电感耦合等离子体质谱法测定原油中V、Cr、Fe、Ni、Cu、Zn、Mo、Co、Pb等16种微量金属元素。研究表明,用CH2Cl2分散原油样品,以浓HNO3-H2O2为消解体系,采用CEM微波消解系统消解样品,各元素线性关系良好,相关系数≥0.9995;检出限可达ng/L;方法精密度较高,相对标准偏差(RSD,n=3)<5.0%;回收率为92%～110%。以w(Ni)/w(V)与w(Fe)/w(V)比值为变量参数对不同原油样品进行聚类分析,表明国内与国外不同地区原油样品中各金属元素含量差异较大。[英文文摘]A method for determination of V,Cr,Fe,Ni,Cu,Zn,Mo Co,Pb,etc in different crude oils was established by inductively coupled plasma-mass spectrometry assisted with organic solvent microwave digestion.The oil sample was digested by microwave using HNO3-H2O2 as oxidant after dispersing in organic solvent(CH2Cl2).The results showed that the detection limits of the method reached ng/L level for sixteen elements.The linear correlation of the method was preferable with the correlation coefficient of better than 0.9995． The recoveries of the method were in the range of 92% ～ 110% with the precision of less than 5.0% RSD (n=3)．The ratios of w(Ni)/w(V) and w(Fe)/w(V) were distinct in different crude oil samples from oversea and domestic，and the index can be used to the cluster analysis for differencing the crude oil samples．国家海洋局第一海洋研究所基本科研业务费专项资助(2010G23);海洋公益性行业科研专项资助(200705011);海洋溢油鉴别与损害评估技术重点实验室开放基金资助(200920

风波水气界面湍流涡旋结构研究

采用有限体积方法和自由界面捕捉格式,发展了基于单流体模型的水气两相流数值仿真模型.所用的对流格式具有良好的数值黏性,不仅能够有效地保证在密度不连续和具有奇异源项条件下的计算稳定性,还可＂隐式＂地模拟亚网格尺度湍流的黏性效应.作为该领域的探索性研究,我们模拟了风驱动水面波（风波）的发生和发展过程,研究了水气两相流空气侧涡旋运动的发展演变规律.揭示了自由界面附近空气侧涡旋的主要结构特点,涡旋结构与雷诺应力的相互关系,以及两相流中流向涡输运过程的主要特征,并与单相槽道平壁湍流进行了对比分析