A rapid intermittent charge method with variable current for VRLA battery

VrlA蓄电池充电分为两段：先控电流，后控电压。对于完全放电态电池（6-fM-4.0），采用恒电流充电使电池达到85%荷电态，最佳充电电流是0.1C，充电时间需要9H。采用变电流间歇充电，充电时间不足3H，可达到92%以上荷电态。最后采用相同的控电压充电使电池恢复至完全充电态，前者需要9H，后者只需6H。本文已给出变电流间歇充电器的原理电路。There are two charging stages: the first one is a charging current control, and the second is charg-ing voltage control.A fully discharged battery (3-FM-4) can be charged up to 85% SOC (state of charge)at the current rate of 0.1C for 9 hours.If the intermittent charge method with variable current is used for thesame condition, the battery can be charged to 92% SOC for less than 3 hours.Afer the first stage both are.chaopd tmder the same charging condition of the constant voltage to reach a full charge state.As for lhe chare-ing duration of the constant voltage, the former needs 9 hours while the latter just 6 hours.The principle cir-cuits of the intendttent charger with variable curmnt have been shown in this paper

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

Electrochemical Behavior of Irreversibly Adsorbed Sb on Au Electrode

用电化学循环伏安法和电化学石英晶体微天平(EQCM)技术研究了Sb在Au电极上不可逆吸附的电化学过程.研究结果表明,在-0.25V到0.18V(vs SCE)范围内,Sb可在Au电极上稳定吸附,并且在0.15V附近出现特征氧化还原峰.根据EQCM实验数据,在电位0.18V时,Sb在Au电极上的氧化产物是Sb2O3;同时Sb的吸附阻止了电解液中阴离子和水在Au电极上的吸附.当电极电位超过0.20V时,Sb2O3会被进一步氧化成Sb5+化合物,同时逐渐从Au电极表面脱附.The electrochemical processes of irreversibly adsorbed antimony (Sbad) on Au electrode were investigated by cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). CV data showed that Sbad on Au electrode yielded oxidation and reduction features at about 0.15 V (vs saturated calomel electrode, SCE). EQCM data indicated that Sbad species were stable on Au electrode in the potential region from-0.25 to 0.18 V (vs SCE);the adsorption of Sb inhibited the adsorption of water and anion on Au electrode at low electrode potentials. Sb2O3 species was suggested to form on the Au electrode at 0.18 V. At a potential higher than 0.20 V the Sb2O3 species could be further oxidized to Sb(V) oxidation state and then desorbed from Au electrode.国家自然科学基金(20673091,20433060

Pt单晶(210)、(310)和(510)阶梯晶面上CO_2电催化还原的表面过程

研究Pt单晶(210)、(310)和(510)三个阶梯晶面上CO_2电催化还原的表面过程.通过改变处理条件获得单晶电极不同的表面结构.研究结果指出,当铂单晶电极表面保持其确定原子排列结构时,对CO2还原的电催化活性随晶面上(110)台阶密度的降低而减小,即Pt(210)>Pt(310)>Pt(510);当三个电极表面发生氧的吸附导致原子排列结构重建时,其电催化活性均有不同程度的提高.虽然其活性顺序未发生变化,但(110)台阶位密度越大的表面其电催化活性增加的程度越高.研究指出Pt单晶电极的表面结构越开放,其电催化活性也越高,并且在外界条件诱导下更易于转变为具有更高反应活性的表面结构.而相对有序的表面结构则比较稳定.研究结果从微观层次获得CO2与Pt单晶电极表面相互作用的规律,深化了对CO2电催化还原表面过程的认识.国家自然科学基金(批准号:20673091,20433060,20373059);; “973”计划(批准号:2002CB211804)资助项

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

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

Electrochemical behavior of irreversibly adsorbed Sb on Au electrode

The electrochemical processes of irreversibly adsorbed antimony (Sb-ad) on An electrode were investigated by cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). CV data showed that Sb-ad on An electrode yielded oxidation and reduction features at about 0.15 V (vs saturated calomel electrode, SCE). EQCM data indicated that Sb-ad species were stable on Au electrode in the potential region from -0.25 to 0.18 V (vs SCE); the adsorption of Sb inhibited the adsorption of water and anion on An electrode at low electrode potentials. Sb2O3 species was suggested to form on the An electrode at 0.18 V. At a potential, higher than 0.20 V the Sb2O3 species could be further oxidized to Sb(V) oxidation state and then desorbed from Au electrode

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