氧化锰表面改性活性炭电极材料的电化学特性

用Mn(NO3)2溶液浸渍-高温热解法对普通活性炭进行表面改性处理以改善其电化学性能. 采用氮气吸附、SEM、XRD等方法研究改性活性炭的比表面积、孔结构、形貌和氧化锰的晶体结构; 用循环伏安、恒流充放电、交流阻抗等电化学方法研究了改性活性炭电极构成的电化学电容器的性能. 结果表明, Mn(NO3)2热解产生的多价态氧化锰有法拉第赝电容效应, 尤其是立方晶形结构的α-Mn2O3, 与活性炭的双电层电容构成了复合电容, 因而改性炭材料的比电容有明显的提高, 其质量比电容达到254 F·g-1, 比未改性炭的165 F·g-1提高了54%. 改性炭电极电化学电容器具有优异的充放电可逆性和稳定性, 而且等效串联电阻较小, 只有0.40 Ω; 经2000次循环的长期测试, 容量保持率几乎达到100%.     

旋转铂盘电极上Cu(phen)_2~(2 )与6-巯基嘌呤的相互作用

在Tris-NaC1*(pH=7.2)缓冲溶液中,应用循环伏安法,微分脉冲伏安法、旋转圆盘电极实验、交流阻抗法及其数据模拟等技术研究了Cu(phen)2 25(phcn=1.10-邻菲咯啉)与6-巯基嘌呤(6-MP)的相互作用.结果显示.Cu(phen)2 2MP与6-MP无论在扩散控制过程或电化学控制过程都发生了相互作用.Cu(phen)2 2及其与6-MP的作用产物于铂电极上均呈现一对氧化还原峰,但后者呈现的氧化还原峰负移.峰电流减小.交流阻抗结果显示,无论6-MP存在与否,Cu(phen)2 2在交流阻抗谱上均呈现两个清晰的电容弧,但当6-MP存在时,电化学反应电阻和电化学吸脱附电阻均增大.Cu(phen)2 2在不同转速下的阻抗拟合结果显示.随转速增大.电化学反应电阻和电化学吸脱附电阻均减小.双电层电容呈增大趋势,而吸脱附电容呈减小趋势:当6-MP存在时.仍然呈现此变化规律.     

电化学合成TiO2/Al2O3复合粉体

以四氯化钛和六水三氯化铝为原料,采用电化学方法制备了TiO2/Al2O3复合粉体.以XRD对粉体进行表征发现,以电解TiCl4和AlCl3的混合溶液得到的粉体中,氧化铝主要分布在颗粒的表面.分别电解TiCl4与AlCl3的水溶液,待成胶后再混合而得到的粉体中,两种成分布比较均匀.对复合粉体进行高温处理,在500℃可以得到R-TiO2/γ-Al2O3的复合粉体,而在950℃可以得到R-mO2/α-舢2哂的复合粉体,在1200℃可以得到ALiO5复合陶瓷粉.     

硫酸溶液中电化学改性石墨电极对Fe3+/Fe2+的电催化性能与准电容特性

通过循环伏安(CV)、恒电流充放电和电化学阻抗谱(EIS)等测试方法,研究了电化学改性石墨电极对硫酸溶液中Fe3+/Fe2+的电催化性能与准电容特性.结果表明:由于电化学改性石墨电极表面存在大量的含氧活性官能团,使其对Fe3+/Fe2+的氧化还原反应具有极高的电催化性能,并具有可逆反应过程特征.在含有0.5mo·lL-1Fe3++0.5mo·lL-1Fe2+的2.0mo·lL-1H2SO4溶液中,其表观面积比电容是不含铁离子硫酸溶液的1.808倍,达到2.157F·cm-2;同时,铁离子浓度的增大也能够进一步提高其电容量.Fe3+/Fe2+电对的加入增加了充放电时间,有效提高了电化学电容器(EC)的电容存储容量和高功率特性.电化学阻抗谱测试同样证实体系具有明显的电容特性.因此,可以利用电化学改性石墨电极表面的含氧活性官能团和溶液中Fe3+/Fe2+的氧化还原特性来共同储存和释放能量.     

氢气还原制备高电容多孔Mn3O4/rGO复合材料

Mn3O4资源丰富、结构稳定,具有较高的理论电容,是一种较有潜力的超级电容器材料,但其较差的导电性却阻碍了其在这方面应用。本论文以实心ε-MnO2微米粉体和具有亲水性的GO粉体为原料,在去离子水中通过磁力搅拌和冷冻干燥制备出具有良好接触的MnO2/GO复合粉体。然后经一步氢气还原处理,使实心ε-MnO2和GO同步转化为具有纳米多孔结构的多孔Mn3O4和RGO,从而获得分散均匀、具有高比表面积和优良导电性的高性能Mn3O4/RGO复合粉体。经电化学测试可知,Mn3O4/RGO复合粉体在2 mV/s的扫描速率下的比电容为25.2 F/g且具有较好的电容留存率。     

酚醛基活性炭纤维孔结构及其电化学性能研究

利用水蒸汽活化法制备了酚醛基活性炭纤维(ACF-H2O), 对其比表面积、孔结构与在LiClO4/PC(聚碳酸丙烯酯)有机电解液中的电容性能之间的关系进行了探讨. 用N2(77 K)吸附法测定活性炭纤维的孔结构和比表面积, 用恒流充放电法和交流阻抗技术测量双电层电容器(EDLC)的电容量及内部阻抗. 研究表明, 在LiClO4/PC有机电解液中, ACF-H2O电极的可用孔径(d)应在0.7 nm以上. 随着活化时间的延长, ACF-H2O的孔容和比表面不断增大, 但微孔(0.7 nm ＜ d ＜ 2.0 nm)和中孔(d ＞ 2.0 nm)率变化很小, 活化过程中孔的延伸和拓宽同步进行, 但过度活化则造成孔壁塌陷, 孔容和比表面迅速下降. 因此, 除活化过度的样品外, 电容量随比表面积呈线性增长, 最高达到109. 6 F•g-1. 但中孔和微孔的孔表面对电容的贡献不同, 其单位面积电容分别为8.44 μF•cm-2和4.29 μF•cm-2, 中孔具有更高的表面利用率. ACF-H2O电极的电容量、阻抗特性和孔结构密切相关. 随着孔径的增大, 时间常数减小, 电解液离子更易于向孔内快速迁移, 阻抗降低, 电极具有更好的充放电倍率特性. 因此, 提高孔径和比表面积, 减少超微孔(d ＜ 0.7 nm), 是提高 EDLC能量密度和功率密度的重要途径. 然而仅采用水蒸汽活化, 只能在小中孔以下的孔径范围内进行调孔, ACF-H2O电极电容性能的提高受限.     

LaF_3表面修饰LiMn_2O_4的合成方法及电化学性能的研究(英文)

通过高温固相法制得尖晶石LiMn2O4,然后在通过简单易行的无水乙醇蒸干法包覆LaF3来修饰LiMn2O4。利用XRD,SEM来表征LaF3修饰的LiMn2O4的结构和形貌特征,并通过电化学测试研究LaF3修饰LiMn2O4的高温和常温下的电化学性能,另外结合电化学阻抗谱(EIS)和循环伏安(CV)考察表面修饰的锰酸锂的循环阻抗和循环可逆性。结果显示:经LaF3修饰过的LiMn2O4仍具有尖晶石结构,并且具有良好的电学性能。其中,以3wt%的修饰效果最好,常温循环100次和高温循环50次的循环保持率分别是91%和90%;而且,EIS和CV分别表明经LaF3修饰的LiMn2O4的电荷传递阻抗明显减小,其循环可逆性也明显提高。     

锈层下碳钢的腐蚀电化学行为特征

采用极化曲线、线性极化电阻(LPR)和电化学阻抗(EIS)研究了海水中带锈碳钢的电化学行为,结果发现:长期浸泡的内锈层对电极过程有较大影响;短期浸泡,LPR和EIS测定的极化电阻(Rp)逐渐增大;而长期浸泡,Rp却逐渐减小;随着浸泡时间的延长,Rp出现了先增大后减小的变化趋势.将锈层逐层剥离后研究了碳钢的电化学行为,并结合傅里叶变换红外(FTIR)光谱和横截面结构分析表明,这主要是因为长期浸泡后,内锈层中出现了具有较高电化学活性的β-FeOOH,并且其含量随着浸泡时间的延长而逐渐增加.当进行电化学测试时,在对体系进行一定程度极化的过程中,β-FeOOH参与了阴极还原反应,使电极过程不再是简单的阳极金属溶解和阴极氧还原,加快了阴极反应速度,从而导致Rp逐渐减小.     

新型质子酸掺杂聚苯胺的合成及其电化学电容行为

用化学氧化聚合法制得了草酸掺杂聚苯胺(H2C2O4-PANI)和柠檬酸掺杂聚苯胺(C6H8O7-PANI),并与盐酸掺杂聚苯胺(HCl-PANI)做了对比研究.用红外光谱(FT-IR)、X射线衍射(XRD)和透射电镜(TEM)对掺杂聚苯胺的结构和形貌进行了表征.用循环伏安,恒流充放电和交流阻抗测试对材料在1 mol/L HCl溶液中的电化学电容行为进行了研究.结果表明:3种酸掺杂的聚苯胺具有不同的空间结构,电化学性能也有差异.与盐酸和柠檬酸掺杂的聚苯胺相比,草酸掺杂制备的聚苯胺表现出更优良的电化学电容行为,单电极比电容可达670 F/g.     

电化学阻抗谱法测定固态聚合物电解质的本体电阻

采用电化学阻抗谱法,对阻抗谱中的聚合物电解质本体电阻（Rb）与膜厚（L）的关系和固体聚合物电解质/惰性电极间的界面阻抗随直流电压的变化趋势进行了研究.结果表明,阻抗谱中聚合物电解质本体电阻（Rb）含有一定的阻塞电极/聚合物电解质间的界面阻抗;由于界面双电层电容的变化,在直流电压0.15～3 V范围内,界面阻抗随电压的增大而减小.     

Effects of Cr2O3 modification on the performance of SnO2 electrodes in DSSCs

In this paper, we demonstrate that Cr(2)O(3), a visible absorbing insulator, can be used as an efficient blocking layer material for the anode of dye-sensitized solar cells (DSSCs). We prepared SnO(2) electrodes surface-modified with Cr(2)O(3) with various Cr/Sn ratios and studied the effect of the modification on the performance of DSSCs. DSSCs with Cr/Sn ratios 0.02, 0.05, and 0.10 showed increased overall photon-to-electricity conversion efficiency from that of pure SnO(2). Especially, the DSSC with the Cr/Sn ratio 0.02 showed a remarkably large increase by 55%. The electrode materials were analyzed by powder X-ray diffraction, transmission electron microscopy, N(2) adsorption studies, and UV-Vis diffuse reflectance spectroscopy. The Cr-containing species appears to be Cr(2)O(3) nanoparticles, spread evenly on the SnO(2) nanoparticles and filling the gap space between SnO(2) particles. The electrochemical properties of the electrodes were characterized by Mott-Schottky plots and electrochemical impedance spectroscopy. As the Cr-content increases, the flat-band potential is negatively shifted. The impedance spectroscopy data show that Cr/Sn = 0.02 and 0.05 samples have lower charge transport resistance at the electrode, which can be explained by the rise of the conduction level due to the charge transfer from the more basic Cr(2)O(3) nanoparticles to SnO(2) nanoparticles. These observations corroborate with the trends of the short-circuit current and the open-circuit voltage of the DSSCs.     

Electrochemical insertion of magnesium ions into V2O5 from aprotic electrolytes with varied water content

The electrochemical performance of V2O5 has been studied in propylene carbonate (PC)-containing magnesium perchlorate [Mg(ClO4)2] electrolytes in view of their application as positive electrode in the rechargeable magnesium batteries. V2O5 exhibited good properties in hosting magnesium ions and its electrochemical performance depended on the amount of H2O in the electrolytes. The highest first discharge specific capacities of V2O5 electrode was up to 158.6 mAh/g in 1 mol dm(-3) Mg(ClO4)2 + 1.79 mol dm(-3) H2O/PC electrolytes. Electrochemical impedance spectroscopy (EIS) and charging-discharging tests showed that a reasonable amount of H2O in the electrolyte solution facilitated the electrochemical performance of V2O5 electrodes.     

LiV3O8在Li2SO4水溶液中的电化学性能

采用低温固相法合成了具有纳米结构的LiV₃O₈材料.扫描电子显微镜（SEM）及透射电子显微镜（TEM）测试显示该材料具有纳米结构.X射线衍射（XRD）表明该材料属于单斜晶系,P2₁Im空间群.并采用循环伏安法（CV）及电化学阻抗谱图测试对该材料在1、2 mol·L^-1Li₂SO₄水溶液及饱和Li₂SO₄水溶液中的电化学行为进行了研究.结果表明,LiV₃O₈在饱和Li₂SO₄水溶液中具有最好的电化学性能.以LiV₃O₈作为负极材料,LiNi_1/3Co_1/3Mn_1/3O₂作为正极材料,饱和Li₂SO₄水溶液作为电解液组成了水性锂离子电池,进行恒流充放电测试,结果表明,在0.5C(1C=300 mA·g^-1)的充放电倍率下,该水性锂离子电池的首次放电比容量为95.2 mAh·g^-1,循环100次后仍具有37.0 mAh·g^-1的放电比容量.     

含稀土钇电极材料的声化学制备及电化学性能

通过超声浸渍法以不同浓度的Y(NO3)3溶液成功地制得几种声化学改性锌粉, 以期改善碱性电池锌电极的电化学性能. 利用扫描电镜(SEM)、X射线衍射(XRD)及电化学测试等方法考察了改性锌粉上Y(OH)3/Y2O3的形成及相应锌电极的耐腐蚀和循环性能. 结果表明, Y(NO3)3浓度为0.036 mol·L-1时, 声化学改性锌粉表面均匀分布着颗粒状的Y(OH)3/Y2O3, 且这些钇化合物优先生长在锌粉表面的缺陷位置, 阻挡了电化学过程中锌酸根离子向碱性电解液中的溶解与扩散, 使得相应锌电极的缓蚀效率达79.6%, 且20次循环伏安曲线的阴、阳极峰电位差比空白样减小了285 mV. 将这种改性锌粉和空白锌粉组装成模拟锌银电池, 在250 mA·cm-2的高放电电流密度下测试发现, 声化学改性锌粉的锌电极从1次到30次循环的放电容量损失仅为62.7 mAh·g-1; 且放电容量在50周期时达到322.6 mAh·g-1, 说明声化学改性锌粉可明显提高电极的放电容量和循环寿命.     

Mg-8Li,Mg-8Li-0.5Ce和Mg-8Li-1Ce合金在0.7mol·L~（-1）NaCl溶液中电化学性能的研究

采用真空熔炼法制备了铸态Mg-8Li,Mg-8Li-0.5Ce和Mg-8Li-1Ce三种Mg-Li合金.采用Tafel极化曲线、恒电势氧化法和电化学阻抗谱法,研究了Mg,Mg-8Li,Mg-8Li-0.5Ce和Mg-8Li-1Ce电极作为Mg-H2O2半燃料电池的阳极材料在0.7 mol·L-1 NaCl溶液中的电化学...     

The diamond/aqueous electrolyte interface: an impedance investigation

We have investigated the electrochemical interface between diamond electrodes and aqueous electrolytes using electrochemical techniques such as cyclic voltammetry and ac impedance spectroscopy. High-quality CVD-grown boron-doped polycrystalline diamond electrodes and IIa single crystalline natural diamond electrodes have been used in this study. In the case of hydrogen-terminated diamond electrodes, the electrochemical interface is dominated by the electrochemical double layer. Frequency-dependent impedance spectroscopy reveals a potential regime in which the contribution of ion adsorption becomes relevant. We have conducted experiments to evaluate the effect of pH and ionic strength on the double layer. Our results suggest that only ions resulting from water auto-dissociation, i.e., hydroxide and hydronium ions, are responsible for ion adsorption and, thus, able to modify the charge at the double layer. In contrast, no effect of the adsorption of several dissolved ions (such as Na+, K+, Cl-) has been observed On the basis of the electrochemical characterization of H-terminated diamond surfaces, we also discuss the phenomenon of the surface conductivity in diamond, as well as the pH sensitivity of the diamond surface. The influence of the O2/OH- and H2/H3O+ redox couples on the origin of the surface conductivity is discussed.     

钡添加剂对二次碱性锌电极性能的影响

采用直接化学合成法制备以钡作添加剂的二次碱性锌电极活性物质,样品的表面形貌及其晶态结构由SEM和XRD表征,并以循环伏安、充放电循环及电化学阻抗谱测定样品的电化学性能.实验表明,锌电极因Ba的添加而生成一种化学式为BaZn(OH)4·xH2O的锌酸钡,改善了电极的电化学性能.此外发现,Zn电极的电化学阻抗谱含有一个对应于电极表面放电产物覆盖率的时间常数.     

锂离子电池正极材料LiMn_(2-2x)Sm_xSr_xO_4的合成及电化学性能

采用高温固相反应合成了一系列的LiMn2-2xSmxSrxO4正极材料(0≤x≤0.1);采用X射线衍射仪分析了合成产物的晶体结构;利用充放电试验测定了产物的电化学性能,利用电化学阻抗谱分析了产物的电化学循环机理.结果表明,所合成的LiMn2-2xSmxSrxO4(x=0,0.01,0.02,0.03,0.04,0.05)样品均保持尖晶石相,属于Fd3m空间群.LiMn1.9Sm0.05Sr0.05O4的电化学性能最佳,首次放电容量为96.8 mAh/g,在3.0~4.4 V区间内50次循环后容量保持率超过96%.与此同时,LiMn2O4和LiMn1.90Sm0.05Sr0.05O4的电极阻抗变化不同,进而影响其电化学性能.     

Experimental study and modeling of impedance of the her on porous Ni electrodes

The electrochemical activity towards the hydrogen evolution reaction of pressed powder electrodes (Ni---Zn and Ni---Al) was studied in alkaline solutions after leaching out the more active element. These electrodes displayed porous character, and electrochemical impedance spectroscopy was used to characterize surface porosity. The influence of overpotential, temperature, poisons, electrode composition and electrolyte concentration was studied and distinction criteria between faradaic and geometrical effects were formulated. Digital simulations of impedance values in different pore geometries were also carried out. The kinetic parameters of hydrogen evolution were determined. The main factor influencing the electrode activity seems to be the real surface area.     

Modified electrodes with Keggin-type silicotungstates and poly(brilliant cresyl blue)

Electrosynthesis of poly(brilliant cresyl blue) in aqueous solution in the presence of Keggin-type polyoxotungstates, [SiW₁₁Fe(H₂O)O₃₉]^5? or [SiW₁₁Co(H₂O)O₃₉]^6?, was used to prepare modified glassy carbon electrodes. The deposited hybrid organic/inorganic films were studied and characterised by cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry showed that the electrochemical features of the polyoxoanions were maintained after immobilisation, with the first tungsten reduction peak involving the uptake of protons from the solution. The chemically modified electrodes were stable, and their preparation was easy to perform. The results provide valuable information for exploring future applications of these films in electrochemical sensors or electrocatalysis.