Electrochemical and In situ FTIR Studies of Maleic Acid Reduction in BF_4

作者自行合成了离子液体[BMIM]BF4,用循环伏安法(CV)、计时电量法(CA)和电化学原位红外反射光谱(in situFTIR),从分子水平考察了离子液体中马来酸在玻碳(GC)电极上的电化学还原过程。结果表明,[BMIM]BF4中马来酸在GC电极上的还原为不可逆过程,测得扩散系数D=9.62×10-8cm2/s;in situFTIRS研究发现,马来酸在离子液体[BMIM]BF4和水溶液中的电还原生成丁二酸的机理不同。在[BMIM]BF4中马来酸还原发生在其中的一个羧基上,即马来酸首先获得一个电子生成阴离子自由基,随后可能获得一个电子生成二价阴离子,或者获得一个电子并在2个H+的作用下生成醛类物质和水。The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborates(BF4) was synthesized and used as both solvent and electrolyte.Electrochemical reduction of maleic acid in the ionic liquid was studied by cyclic voltammetry(CV),chronoamperometry(CA) and in situ FTIR spectroscopy.The results demonstrated that the reduction of maleic acid on GC electrode is an irreversible process controlled by diffusion.The diffusion coefficient D of maleic acid is determined to be 9.62×10-8 cm2/s.in situ FTIR results illustrated that the reduction of maleic acid in ionic liquids occurs on the carboxyl.The first step is to geaerte radical anions,which are reduced then to aldehyde species and water with two hydrogen ions.国家自然科学基金(批准号:20673091,20833005)~

Sb-Se系和Ge-Sb-Te系相变光盘记录介质微观结构及光学性能研究

利用X射线衍射仪 ,分光光度计对Sb Se系和Ge Sb Te系相变光盘记录介质材料非晶态薄膜相变前后结构的变化 ,光学性能进行了系统的研究 ,X射线衍射分析表明 :SbSe非晶态薄膜退火后有Sb的析晶峰 ,SbSe2 有Se的析晶峰 ,符合化学计量比的Sb2 Se3 全部是Sb2 Se3 的共晶峰 .GeSb2 Te4 非晶态薄膜在热退火过仇逐首先形成fcc亚稳相 ,升高退火温度 ,Fcc相转变为稳定的hex相 ,GeSb4 Te4 非晶态薄膜退火后在发生上述变化的同时 ,还有Sb的析晶峰 .分光光度计测试表明 :Sb Se系非晶态的光稳定性很不理想 ,随着波长的改变 ,反射率变化太快 .对于Ge Sb Te系合金 ,在各种波段处 ,两种合金都有较大的反衬度 ,其非晶态的光稳定性也较理想 ,随着波长的改变 ,反射率变化不

Electrochemical and in situ FTIRS of maleic acid reduction in[BMIM]BF_4 on Pt electrode

采用循环伏安法(CV)、计时电量法(CA)和电化学原位红外反射光谱(in situ FTIRS),从分子水平上研究了离子液体[BMIM]BF_4中马来酸在Pt电极上的电化学还原过程。结果表明,[BMIM]BF_4中马来酸在Pt电极上的还原是受扩散控制的准可逆过程,测得扩散系数为1.0×10~(-7)cm~2·s~(-1);in situ FTIRS研究发现, [BMIM]BF_4中马来酸在Pt电极上的还原发生在其中的一个羧基位上,即马来酸首先获得一个电子生成阴离子自由基,随后再获得一个电子生成二价阴离子。Electrochemical reduction of maleic acid in the ionic liquid was studied by cyclic voltammetry (CV),chronoamperometry(CA)and in situ FTIR spectroscopy.The results demonstrated that the reduction of maleic acid on Pt electrode is a quasireversible process controlled by diffusion.The diffusion coefficient of maleic acid is determined to be 1.0×10~(-7)cm~2·s~(-1).In situ FTIRS results illustrated that the reduction of maleic acid in ionic liquids occurs on the carboxyl.The first step is to generate radical anions, which are reduced to aldehyde species.国家自然科学基金项目(20833005,20873113)。~

Sb-Se系和Ge-Sb-Te系相变光盘记录介质的热力学参数、微观结构及光学性能

利用DSC,X射线衍射及分光光度计,对Sb-Se系和Ge-Sb-Te系记录介质的热力学参数、非晶态薄膜相变前后结构的变化及光学性能进行了系统的研究,结果表明:Sb—Se系非晶态的光稳定性很不理想,随着彼长的改变,反射率变化太快。对于Ge—Sb—Te系的两种成分合金,在各种波段处都有较大的反衬度,其非晶态的光稳定性也比较理想,随着波长的改变,反射率变化不大

EFFECT OF NO_2 AND Cl~- ON THE CORROSION BEHAVIOR OF REINFORCING STEEL IN SIMULATED CONCRETE PORE SOLUTIONS

作者简介:乔冰：女. 1984年生，硕士生。[中文摘要]应用极化曲线法和电化学阻抗技术研究了NO_2~-和Cl~-对钢筋在不同pH值的模拟混凝土孔隙液中的腐蚀行为,结果表明,钢筋耐蚀性与溶液的pH值,以及NO_2~-和Cl~-的浓度相关,pH值的降低和Cl~-浓度的增高都会使钢筋的耐蚀性降低。在含Cl~-的模拟液中,随着NO_2~-浓度升高,钢筋腐蚀速率降低,在pH值为12.50和10.50的溶液中,当[NO_2~-]/[Cl~-]≥0.4时,NO_2~-对钢筋具有良好的阻锈作用。[英文摘要]Under normal conditions,reinforcing steel in concrete maintaills its passivity because of the high alkalinity of the concrete pore solution. However, steel passivity rnay be broken and the steel corrosion takes place due to concrete carbonation and/or chloricle ingress. In fact,premature failure of reinforced concrete structures due to the steel corrosion has been a major problem in civil engineering. Therefore, the study of corrosion and protection of reinforcing steel is of indispensable importance to prolonging the service life of reinforced concrete structures. The application of inhibitors is an effective and economical method to prevent the corrosion of reinforcing steel.NaN02 is a notable corrosion inhibitor which is effective in the steel corrosion control by reacting with ferrous ions to form a protective ferric oxide film on the steel surface,but unfortunately it can also accelerate the steel corrosion when the amount of nitrite is insufficient in a medium. In the present work,the linear polarization and electrochemical impedance spectroscopy were used to study the effect of nitrite and chloride ions on the corrosion behavior of reinforcing steel in simulated concrete pore solutions with different pH values. The results showed that the corrosion resistance of reinforcing steel is related with the pH value of the solution, nitrite ion concentrations and chloride ion concentrations. The drop of pH value and the increase of chloride ion concentration would result i且the clecline of corrosion resistance of reinforcing steel in the solution. The corrosion rate of reinforcing steel decreased with the NO2-concentration increasing in the simulated concrete pore solutions with Cl-, and the N02 ions had a good inhibiting effect on the steel when the concentration ratio of N02 and Cl- was 0.4 or higher for the solutions of pH=12.50 or pH=10.50.国家自然科学基金项目20473066; 国家自然科学基金重点项目50731004; 国家科技支撑计划项目2007BAB27B04资

背照式GaN／AlGaN p-i-n紫外探测器的制备与性能

文章研究了p-GaN／i—GaN／n-Al0.3Ga0.7N异质结背照式p-i—n可见盲紫外探测器的制备与性能。器件的响应区域为310～365nm，最大响应率为0．046A/W，对应的内量子效率为19％，优值因子R0A达到1．77×10^8Ω·cm^2，相应的在363nm处的探测率D^＊=2．6×10^12cmHz^1/2W^-1