酸性镀铜添加剂对电沉积循环伏安曲线成核环的影响

金属电沉积的循环伏安(CV)曲线上的成核环可以用于分析添加剂对电沉积的影响及其作用机理。以常用的3种酸性镀铜添加剂为例,探讨了不同添加剂下成核环的形成特点,并从其成核环的位置以及构成成核环的电流曲线来探讨添加剂对铜沉积的影响及其机理。结果表明:当成核环分别位于不加添加剂的阴极电位和阳极电位方向时,添加剂对金属电沉积分别具有阻化和促进作用;阴极扫描方向电流密度Jb和回扫的阳极电流密度Ja是CV曲线成核环的两个特征参数,添加剂作用下的Ja和Jb与不加添加剂的接近,表明添加剂通过吸附-脱附机理影响金属的沉积,反之表明添加剂在电极表面参与化学反应。

Lead electrodeposition from alkaline solutions containing xylitol

The electrodeposition of lead in alkaline solutions containing xylitol （1, 2, 3, 4, 5-pentahydroxypentane） was studied. The lead electrodeposition and the chemical stability of xylitol in alkaline solutions were investigated by cyclic voltammetry. Apparent activation energy, apparent transfer coefficient and exchange current density were obtained by linear sweep voltammetry. Initial stages of lead electrocrystallization were determined by chronoamperometry. Voltammograms of a AISI 316 stainless steel electrode in xylitol solution exhibit no current in the potential range of-1.3 V to 0.75 V （vs Hg/HgO）, implying that xylitol is stable to oxidation and reduction. The apparent activation energy, apparent transfer coefficient and exchange current density were calculated to be 35.15 kJ/mol, 1.56 and 9.65x10^-5 A/m^2. Analysis of the chronoamperometric responses implies three-dimensional growth of nuclei, with the type of nucleation depending on overpotential.

Electrochemical behavior of Li incorporation in Al in LiTFSI/KTf molten salt electrolyte

The electrochemical behavior of lithium incorporated in aluminum electrode in LiTFSI/KTf （lithium bis （trifluoromethylsulfonyl） amide/CF3SO3K） molten salt electrolyte was studied by a variety of electrochemical techniques including cyclic voltammetry, chronopotentiometry and chronoamperometry. The reduction reaction is found involving a nucleation process on the aluminum electrode. The results of chronopotentiometry indicate that the process of lithium incorporation in aluminum is smooth and uniform. The galvanostatic cycle experiments show that the coulombic efficiency is very low in the first cycle, which is mainly due to the ＂retention capacity＂ of Li-Al alloys. This characteristic is testified by the results of XRD and SEM. The results of chronoamperometry indicate that the incorporation of lithium into aluminum for the formation of a-phase Li-Al alloy is limited by its diffusion rate, with a measured diffusion coefficient of 1.8× 10^-10 cm2/s.

An improved activity-based costing model for product cost estimation applied in a complex manufacturing environment

In order to evaluate and estimate me cosEs oi prouuct~ plt, uu^u e vironment properly, an improved activity-based costing （ABC） model is presented. By utilizing the input-output analysis method, the complex consumption relationships in a complex manufacturing environment are first expressed. The consumption characteristics （mainly presented by the activity rates） of all production activities are extracted by solving these relationships. Then with the con- sumption characteristics and operating parameters of these activities, the detailed cost consumption of a product in its manufacturing process is estimated. A case study is finally given based on the compressor products of a manufacturing company, and its effectiveness is shown. As the cost influ- ence of complex consumption relationships is fully considered, the limitation of traditional ABC method is overcome, and therefore a high accuracy in product cost estimation under the complex manufacturing environment can be achieved.

Ag(I)-Catalyzed Addition of Cyclopropenones and Alcohols via C—C Bond Cleavage

An efficient method for the synthesis of α-phenylcinnamates via silver catalyzed C—C bond activation reaction of cyclopropenone and alcohol was developed.This protocol features a simple reaction system,specific regioselectivity,good functional group compatibility and good yields.It is of great significance for the later modification of natural products.

Reaction mechanism and chemoselectivity of gold(Ⅰ)-catalyzed cycloaddition of 1-(1-alkynyl) cyclopropyl ketones with nucleophiles to yield substituted furans

The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.

Initial stages of copper electrodeposition from acidic sulfate solution in the presence of alklpyridinium hydrosulfate ionic liquids

The effect of two alklpyridinium hydrosulfate based ionic liquids(ILs)including N-butylpyridinium hydrogen sulfate(BpyHSO4)and N-hexylpyridinium hydrogen sulfate(HpyHSO4)as additives on the nucleation and growth of copper from acidic sulfate bath was investigated using cyclic voltammetry,chronoamperometric and scanning electron microscopy techniques.Results from cyclic voltammetry indicated that the two studied additives had a blocking effect on copper electrodeposition process and this effect initiated by HpyHSO4was more pronounced in comparison to BpyHSO4.Dimensionless chronoamperometric current-time transients for the electrodeposition of copper from the bath free of additives were in good accord with the theoretical transients for the limiting case of instantaneous three-dimensional nucleation with diffusion-controlled growth of the nuclei.However,the instantaneous nucleation mechanism observed in the additive-free bath was changed to a more progressive one when additives were present in the bath.Surface morphology analysis indicated that alklpyridinium hydrosulfate ILs can induce the formation of leveled and finer grained deposits by the adsorption of additive at the first stages of deposition process,leading to decrease of the nucleation and growth rate of nuclei.