热处理碳纸电极上VO2+/VO+2氧化还原动力学

在不同温度下热氧化处理碳纸, 用循环伏安、极化曲线和交流阻抗方法研究碳纸电极上VO2+/VO+2氧化还原动力学. 循环伏安和极化曲线结果表明, 随着热处理温度的升高, VO2+/VO+2氧化还原反应的速率常数及交换电流增大. 建立了VO2+/VO+2氧化还原反应的交流阻抗等效电路模型. 拟合结果表明, 热处理增大了碳纸电极表面的双电层电容, 减小了VO2+/VO+2氧化还原反应的电荷转移电阻. 用循环伏安和交流阻抗两种方法求得的VO2+和VO+2的扩散系数基本相同, 表明所构建的交流阻抗等效电路模型与电极反应过程相符合.     

2，2′-联吡啶In（Ⅲ）配合物与DNA作用的电化学研究

应用循环伏安法、微分脉冲伏安法和交流阻抗法研究了配合物In(bpy)Cl3·H2O与DNA在Tris-HCl缓冲溶液(pH=7.2)中的相互作用.结果表明配合物中心In(Ⅲ)离子的循环伏安曲线上呈现一对准可逆的氧化还原波,DNA与配合物作用后,配位中心离子的氧化还原峰电流明显降低,扩散系数减小,电化学反应阻抗增大,式量电位负移,表明该配合物与DNA的作用方式为静电结合.     

2,2'-联吡啶In(Ⅲ)配合物与DNA作用的电化学研究

应用循环伏安法、微分脉冲伏安法和交流阻抗法研究了配合物In(bpy)Cl3.H2O与DNA在Tris-HCl缓冲溶液(pH=7.2)中的相互作用.结果表明:配合物中心In(Ⅲ)离子的循环伏安曲线上呈现一对准可逆的氧化还原波,DNA与配合物作用后,配位中心离子的氧化还原峰电流明显降低,扩散系数减小,电化学反应阻抗增大,式量电位负移,表明该配合物与DNA的作用方式为静电结合.     

循环伏安法定性分析矿物中某元素硫氧化物占比

根据硫化矿和氧化矿在电解液为硫酸钠的三电极体系中循环伏安曲线的差异，建立了循环伏安法定性分析矿物中某元素硫氧化物占比的方法，以铜的硫化物(黄铜矿)和氧化物(孔雀石)纯矿物进行循环伏安法测试。结果表明，在扫描速率0.1 V/s,扫描电压范围-0.8 V～0.8 V时，黄铜矿循环伏安曲线出现氧化还原峰，孔雀石循环伏安曲线未见明显氧化还原峰；黄铜矿和孔雀石混合物循环伏安曲线上的氧化还原峰电位与单一黄铜矿的氧化还原峰电位几乎一致，但峰电位对应的电流大小与矿物占比存在一定的关系。由此，可以通过循环伏安法定性判断混合矿中黄铜矿与孔雀石的占比，实现循环伏安法定性分析矿物中某元素硫氧化物占比。     

超氧化物歧化酶在纳米金/L-半胱氨酸修饰金电极上的电化学行为

通过L-半胱氨酸将纳米金修饰到金电极上,把超氧化物歧化酶(SOD)固定在修饰电极表面,制备了SOD-纳米金/L-半胱氨酸修饰电极。运用交流阻抗法、循环伏安法等方法表征了该电极,发现SOD在该电极上于0.15V和-0.05V左右产生较明显的氧化还原峰,在0.04～0.24V/s扫描速率范围内,其还原峰电流与扫描速速呈线性关系,表明该电极过程受吸附控制。研究了H2O2对SOD-纳米金/L-半胱氨酸修饰电极伏安行为的影响,发现该电极的还原峰电流与H2O2浓度在1.0×10-6～2.0×10-4mol/L范围内呈良好的线性关系,相关系数为-0.996,可用于对H2O2的分析检测。     

铜与烟酸和8-羟基喹啉配合物的电化学行为及与DNA的相互作用

采用循环伏安法研究了铜与烟酸和8-羟基喹啉配合物(Cu(Hq)(NA)0.5(Hq=8-羟基喹啉,NA=烟酸))的电化学行为。此外,以鲱鱼精DNA为靶点,采用紫外吸收光谱、DNA粘度滴定和差分脉冲伏安法,从分子水平研究了该配合物与DNA的键合方式。结果发现:配合物的中心Cu~(2+)在循环伏安图上呈现明显的氧化还原峰,峰电流随扫描速度的增加呈增加趋势,并且与扫描速度成正比。配合物的吸收峰强度随着DNA的加入减色显著,氧化还原峰电流也随之减小,式量电位发生正移;粘度实验结果发现DNA的相对比粘度随配合物的加入而增大。这些结果表明配合物与DNA通过嵌插方式发生作用。     

Keggin型缺位硅钨杂多阴离子的电化学性质及电催化还原H2O2

应用循环伏安、方波伏安和交流阻抗法研究了Keggin型缺位硅钨杂多阴离子SiW11O398-(SiW11)在0.1mol.L-1NaHSO4+Na2SO4溶液中的电化学性质及其对H2O2还原的间接电催化作用.结果表明,SiW11的酸性水溶液在玻碳(GC)电极上显示两对可逆的还原-氧化波,对应的电荷迁移数均为1,且有2个质子参与反应.根据第1对波的还原峰电流与扫描速率平方根关系得到SiW11在溶液中的扩散系数DO为8.92×10-6cm2.s-1.SiW11对H2O2的还原具有明显的电催化活性,催化峰电位随溶液pH的降低而正移,峰电流增大.质子H+在催化反应中起协同促进作用.实验测定该电催化过程的均相准一级反应速率常数为0.30 s-1.SiW11电催化还原H2O2的机理被认为是经过形成所谓"七配位过氧化物"而发生的.     

对苯二酚在普鲁士蓝修饰电极上的电化学行为

利用循环伏安法制备普鲁士蓝修饰玻碳电极(PB/GC),电极对对苯二酚具有良好的电催化作用,PB/GC电极上的氧化还原峰电流比裸电极大两个数量级,峰电位之差从0.83V减少到0.48V;考察了修饰电极膜的厚度与峰电流关系,当扫描圈数大于60圈时,峰电流不再随着薄膜厚度的增加而变大,峰电流与扫描速度的平方根呈线性关系,说明膜电极在界面传质为线性扩散控制;采用计时电量和电化学阻抗法研究对苯二酚的电化学行为,求得在不同厚度修饰电极膜上的扩散系数,此电极可用来快速检测对苯二酚。     

Eastman-AQ/四硫富瓦烯修饰碳纤维微盘电极

利用新型的阳离子聚合物膜将四硫富瓦烯修饰到电极表面上，并研究了修饰电极的电化学行为。研究了浸泡时间、扫描速度和支持电解质对修饰电极性能的影响；循环伏安法、计时电流法和交流阻抗法表明四硫富瓦烯在膜中的扩散是控制步骤。四硫富瓦烯在膜中的第一对氧化还原峰呈现可逆的、单电子反应。用循环伏安法测得了ＴＴＦ＋ＴＴＦＺＴＴＦ反应的平衡常数。     

阿昔洛韦在硼掺杂金刚石电极上的电化学行为及其与DNA相互作用的研究

利用硼掺杂金刚石(BDD)电极通过循环伏安法和微分脉冲伏安法研究了阿昔洛韦在0.10 mol/L磷酸盐缓冲溶液(pH 7.4)中的电化学行为及其与DNA的相互作用.与玻碳电极相比,阿昔洛韦在BDD电极上的循环伏安曲线在1.17 V处的氧化峰电流更大,背景电流较低.根据峰电位随溶液pH值和扫描速率的变化趋势考察了阿昔洛韦...     

Electrically conductive epoxy‐based nanocomposite adhesives loaded with silver‐coated copper and silver‐coated reduced graphene oxide nanoparticles

In this research, a conductive adhesive based on epoxy resin as the polymer matrix and silver‐coated copper powder and silver‐coated reduced graphene oxide as conductive fillers was synthesized. Graphene oxide was synthesized by modified Hummer's method. It was reduced and modified by silver powder. Copper particles were coated with silver using the electroless plating method. Finally, conductive nanocomposite adhesives were prepared using conductive fillers with different weight fractions. The structural properties of fillers were identified by Fourier‐transform infrared (FTIR) and induced coupled plasma (ICP) analysis and the morphology of the samples by scanning electron microscopy (SEM). Finally, conductive properties, lap shear strength, and thermal stability of adhesive were evaluated. The conductive adhesive prepared with optimized properties have 70% weight percentage silver‐coated copper powder and 1% weight percentage silver‐coated reduced graphene oxide. The bulk resistivity of the optimum sample was 1.6 × 10^‐2 Ω.cm, and the lap shear strength was 7.10 MPa. Also, thermogravimetric analysis showed that the weight loss of adhesive decreased from 88.72% to 30.55% during heating, which showed the addition of fillers improves the thermal stability of adhesive.     

热处理对线团状二氧化锰结构及其电化学性质的影响

以氯化锰与高锰酸钾为原料, 在低浓度下大数量合成由无数片状纳米层组成的线团状二氧化锰粒子. 采用X衍射, 扫描电镜, 液氮等温吸附脱附、循环伏安、交流阻抗及恒流充放电等方法研究了温度对产物结构及电化学性质的影响. 结果表明处理温度升高, 微孔减少, 比表面积减小, 孔径变大, 在300 ℃以下二氧化锰粒子的结构保持无定型结构. 交流阻抗测试显示随着处理温度的升高, 样品的法拉第电荷传递能力和离子在电解液与活性材料界面的扩散能力均得到提高. 比电容测试显示在200 ℃处理的二氧化锰具有最高的比电容, 以1 mol·L^-1 Na₂SO₄为工作介质, 扫速为2 mV·s^-1时, 其比电容是210.6 F·g^-1. 该研究表明: 材料的电化学性质可以通过热处理进行调整, 适当的热处理能提高该材料作为超级电容器活性材料的性质.     

Production from ilmenite of TiO2-supported catalysts for selective catalytic reduction of NO with NH3

Economic production of titanium dioxide (yield >98 %) from ilmenite has been achieved by use of a modified sulfate reduction process. A series of samples were prepared by varying the concentration of titanium dioxide nuclei (0.2, 0.3, and 0.6 %) and further impregnation with antimony and vanadia. The structural and acidic properties of the samples were comprehensively studied by X-ray diffraction (XRD), transmission electron microscopy, BJH pore size distribution, and temperature-programmed desorption of NH₃. The XRD results revealed the presence of intense peaks from anatase titanium dioxide. Enhancement of surface area was observed for second-time filtered samples, possibly because of loss of iron from the bulk. As a result, formation of additional micropores was apparent from N₂ adsorption and desorption isotherms. Among all the antimony and vanadia-doped samples, the first-time filtered sample with the low concentration of nuclei (0.2 %) had the highest catalytic activity at low temperatures, owing to its larger pore size and abundant acidic species.     

尖晶石LiMn2O4纳米粉的合成 及其交流阻抗性能研究

以LiOH和电解二氧化锰(EMD)为原料,葡萄糖为还原剂,制备了粒径为200nm左右的球状尖晶石LiMn2O4纳米粒子,并用X射线衍射(XRD)和扫描电镜(SEM)对样品进行了结构和形貌的表征.在循环伏安测试(CV)峰电位下研究了该材料嵌脱锂相变过程中的交流阻抗(EIS)图谱,并提出一种新的等效电路对EIS图谱进行拟合...     

The electrical properties of chemically obtained barium titanate improved by attrition milling

Barium titanate ceramics were prepared using the nanopowder resulting from a polymeric precursor method, a type of modified Pechini process. The obtained nanopowder was observed to agglomerate and in order to de-agglomerate the powder and enhance the properties of the barium titanate the material was attrition milled. The impact of this attrition milling on the electrical properties of the barium titanate was analysed. The temperature dependence of the relative dielectric permittivity showed three structural phase transitions that are characteristic for ferroelectric barium titanate ceramics. The relative dielectric permittivity at the Curie temperature was higher for the attrition-treated sample than for the non-treated barium titanate. The dielectric losses were below 0.04 in both barium titanate ceramics. The grain and grain-boundary contributions to the total resistivity were observed using impedance analyses for both ceramics. A well-defined ferroelectric hysteresis loop and piezoelectric coefficient d₃₃ = 150 pC/N were obtained for the ceramics prepared from the de-agglomerated powder. In this way we were able to demonstrate that by attrition milling of chemically obtained powders the ferroelectric and piezoelectric properties of the ceramics could be enhanced.     

ZnO/TiO2复合涂层电极的制备及其光电性能

以氧化铟锡导电玻璃为基材,采用电泳沉积法制备负载型ZnO/TiO2复合涂层,经450℃后续烧结处理后,采用XRD、SEM、EDX和UV-Vis DRS对ZnO/TiO2复合涂层进行表征;在pH=7.00的磷酸盐缓冲溶液中,分别测试ZnO/TiO2复合涂层电极在紫外灯和100 W白炽灯辐照下的电化学阻抗谱、Tafel极化曲线和循环伏安等电化学性质。结果表明:ZnO以200~300 nm晶粒分散于复合涂层中,质量百分比为0.74%;ZnO/TiO2复合涂层在可见光区有一定的吸收;在可见光辐照下ZnO/TiO2复合涂层电极具有较好的光电活性,并对水的分解具有较强的光电催化活性。     

Structure of hydrated tin dioxide doped with Sb(III) ions

The effect of antimony doping of tin dioxide at Sb/Sn = 0.2–2.5 on the physical properties and structure of air-dry samples of hydrous tin dioxide, SnO₂ ? nH₂O (HTD), was studied by IR and Raman spectroscopy, powder X-ray diffraction, impedance measurements, TGA, and electron microscopy. The doped materials retained the structure of undoped HTD materials if the Sb/Sn ratio did not exceed the threshold value of 1.0. When Sb/Sn > 1, crystalline antimony oxide admixture appeared. The data of IR spectroscopy attested to the presence of two types of water in HTD-Sb, namely, physisorbed and chemisorbed water. The major part of water of the former type can be removed by evacuation at room temperature. Chemisorption occurs upon coordination of water molecules by metal ions through the formation of metal–oxygen bonds. Water molecules of the latter type are retained in evacuated samples at room temperature and on heating above the boiling point of liquid water. By impedance spectroscopy, HTD-Sb samples were shown to possess fairly high proton conductivity at high humidity; however, the conductivity decreased by two orders of magnitude after partial removal of water molecules of the former type. This attests to the destruction of the loosely bound hydrogen bond network, across which proton transfer takes place. It was also found that under conditions of constant humidity, the proton conductivity successively decreases with increasing antimony concentration. This is attributable to the fact that Sb(III) ions polarize the local environment to a lesser extent than Sn(IV) ions.     

Ag-TiO2-MnO2复合材料的制备与电化学性能研究

采用高温固相法制备了Ag-TiO₂共修饰的二氧化锰锂电池阴极材料,通过X射线衍射仪（XRD）、扫描电子显微镜（SEM）、傅立叶红外光谱仪（FT-IR）、X射线光电子能谱仪（XPS）、能量散射X射线能谱（EDS）、循环伏安测试（CV）、恒流放电测试、交流阻抗测试（EIS）等分别检测了所制备样品的物理-化学特性及相应的电化学性能特征.结果表明：空白二氧化锰与修饰后二氧化锰均为β 晶型,相比于未修饰样品,Ag-TiO₂-MnO₂ 样品的形貌得到了明显的改变.修饰后样品大倍率的放电比容量显著提升,1C 下的容量由 75mAh·g^-1 增加到 115mAh·g^-1,Ag-TiO₂-MnO₂ 样品 Mn-O 键能的增强对于抑制放电过程中体积膨胀也有一定作用,可以使二氧化锰材料保持较好的结构稳定性.     

CoSm_xFe_(2-x)O_4铁氧体纳米粉晶的制备及其电磁性能

用W/O微乳液法制备了CoSmxFe2-xO4(x=0.00,0.02,0.04,0.06,0.08,0.10)铁氧体纳米粉晶。用X射线衍射仪(XRD),透射电子显微镜(TEM)、振动样品磁强计(VSM)和阻抗/材料分析仪表征了样品的结构、形貌和电磁性能。结果表明,掺杂少量Sm3+对样品的晶体结构没有影响,但其晶粒尺寸、饱和磁化强度、矫顽力和电磁损耗性能等都有不同程度的改变。样品的晶粒尺寸随Sm3+含量的增加而减小,在35~20 nm之间变化;而饱和磁化强度随着钐掺杂量的增加呈先减小后增大的变化趋势(x=0.00→0.04→0.08,Ms=52.95→51.03→52.56emu.g-1);当钐掺杂量x分别等于0.6和0.4时,其磁损耗性能和电损耗性能在1 MHz~1 GHz的频率范围达到最大,且低频区优于高频区。     

Antimony Doped Tin Oxide Nanoparticles Deposited onto Nb−TiO2 Nanotubes for Electrochemical Degradation of Bio‐refractory Pollutions

To improve the service life of SnO₂?Sb electrodes in degradation of refractory wastewater, we report anodic information of tin oxide antimony on top of Nb?TiO₂ nanotubes (Nb?Ti/Nb?TiO₂?NTs/ATONPs) prepared through screen‐printing. It was found that the Nb?Ti/Nb?TiO₂?NTs/ATONPs anodes presented a significantly enhanced in electro‐catalytic oxidation performance (in Acid Red 73) compared to titanium‐based tin antimony electrodes (Ti/ATONPs). Additionally, the electrochemical properties and the stability were further studied by the electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry (CA) measurements and accelerated life test, respectively. These results indicated that Nb?TiO₂?NTs/ATONPs anode possessed Nb?TiO₂ nanotubes which exhibited a higher oxygen evolution potential (2.24 V vs. Ag/AgCl), as well as a better wettability, a larger current at constant potential and 2.1 times longer lifetime than the conventional Ti/ATONPs anode.