NdF3-LiF-Nd2O3熔盐体系中下阴极电解金属钕研究

设计了下阴极结构的稀土金属电解槽,该电解槽底部以钨材料为容器兼阴极,上部悬挂多块石墨作阳极,在NdF3·LiF-Nd2O3体系中,探索研究了液态下阴极电解制备金属钕的工艺技术条件.研究表明,在槽温990～1020℃,阴极电流密度1～3 A·cm-2.槽电压5.6 V条件下,电解可平稳进行,电流效率达65.64%,稀土回收率达88%～92%;该工艺与目前主流上插阴极电解工艺相比,其电解温度和槽电压明显降低,降低了电耗.     

新型蓝光材料: 氟代三联(9,9-二苯基)芴的合成及其光电性能研究

使用HF/吡啶法在芴环的4位引入了氟原子, 使用五氟氯苯格氏试剂在芴环的9位引入了全氟苯, 合成了五个氟取代三联(9,9-二苯基)芴化合物. 测量了该系列化合物的电化学、光学和电致发光性能, 氟原子的引入提高了化合物的电子传输能力. 在溶液和薄膜状态下, 该类化合物都呈现出稳定的蓝光发射(色坐标x＝0.156, y＝0.078). 由化合物6f制备的简单器件的启亮电压为6 V, 最大亮度为452 cd/m2.     

阳极氧化铝模板法可控制备金属纳米线和纳米管阵列的生长机制

利用阳极氧化铝模板(AAO)进行Ni的电化学沉积, 通过在溶液中引入螯合剂控制电解质的有效浓度和电沉积的过电位, 实现了Ni纳米线和纳米管阵列的可控制备. 通过分析电沉积过程中纳米线和纳米管在不同位置生长速率(侧壁(Vw)和底端(Vb))的控制因素, 我们提出了纳米线和纳米管生长的可能机制. 当电解质浓度高而还原电位更负(如-1.5 V)时, 或者当电解质浓度低而还原电位较负(如-0.5 V)时, Vw>Vb, 可以获得Ni纳米管阵列; 当电解质浓度高而还原电位较负(如-0.5 V)时, 或者当电解质浓度低而还原电位更负(如-1.5 V)时, Vw≈Vb, 可以获得Ni纳米线阵列. 这种生长机制适用于多种金属纳米管或者纳米线阵列的可控制备.     

一种红光铱配合物的合成和电致发光性能

以1-(4-三氟甲基苯基)异喹啉(tfmpiq)为主配体,二(二(4-三氟甲基苯基)膦酰)胺(tfmtpip)为辅助配体,成功合成了Ir髥配合物Ir(tfmpiq)2(tfmtpip),并得到了配合物的晶体结构。配合物Ir(tfmpiq)2(tfmtpip)的分解温度为373℃,具有良好的热稳定性。Ir(tfmpiq)2(tfmtpip)的发射光谱主要是MLCT发射,峰位置为613 nm,量子效率为3.7%,HOMO和LUMO轨道能级分别为-5.62和-3.54 e V。基于Ir(tfmpiq)2(tfmtpip)的器件ITO/TAPC(40 nm)/Ir(tfmpiq)2(tfmtpip)(x%)∶mCP(20 nm)/TmPyPB(40 nm)/LiF(1 nm)/Al(100 nm),当掺杂浓度为4%(w/w)时,器件达到最大功率效率和电流效率分别为5.73 lm·W-1和7.13 cd·A-1,而且器件在12.8 V的驱动电压下达到亮度10 542 cd·m-2。     

基于掺杂氟的二氧化锡导电玻璃的苏丹红I号电化学降解研究

研究了基于掺杂氟的二氧化锡(FTO)导电玻璃的苏丹红I号电化学降解工艺,考察了电解质浓度、环境酸度、外加电压、初始浓度等因素对苏丹红I号去除率的影响.结果表明,以FTO导电玻璃为阳极,控制电解电压为12 V,对含20 g/L氯化钠的苏丹红I号(0.01 g/L)溶液(p H 9.0)进行电化学降解20 min后,苏丹红I号的脱色率可达到60%.     

涂钼石墨管分子吸收光谱法测定微量氟

本文对AIF分子吸收光谱法测量微量氟进行研究.使用涂钼石墨管可使灵敏度有较大提高.采用铂空心阴极灯做光源,峰值吸收测量方式,复合基体改进剂并先于氟进样,二次干燥等诸项技术联合运用时,可使AIF-MAS法具有实用意义.方法的灵敏度为9.6×10~(11)g/1%A,精密度为4.9%,在测试的浓度范围内,有两个线性范围:0.075～0.6μg·ml~(-1);0.6～1.5ug·ml~(-1).     

V（Ⅲ）-V（Ⅳ）电解液的电解合成

以硫酸氧钒(VOSO4)为原料,电解合成了用于制备钒电池的混合价态钒离子[V(Ⅲ)-V(Ⅳ)]电解液.较适宜的电化学反应条件为:以Ir-Ta/Ti为阳极,导电石墨板为阴极;4 mol·L-1 H2SO4为阳极电解液,2 mol·L-1 VOSO4-2 mol·L-1H2SO4混合溶液为阴极电解液,于1A电解6 h.在此条件下进行电化学反应,电解液的电化学活性高,电导率稳定;电解过程实现了较高的电流效率(接近100%)和较低的电能损耗(345 Wh·kg-1).     

载铁（Ⅲ）—配位体交换棉纤维素吸附剂对饮用水中砷（V）和氟联合去除的研究

使用新型载铁（Ⅲ）－配位体交换棉纤维素吸附剂，通过静态和动态吸附实验，研究了饮用水中砷酸钠[砷（V）]和氟化钠（氟）联合去除的效果和浓度因素的影响以及吸附剂经过反复吸附－洗脱再生－再吸附后性能的稳定性。结果表明，该吸附剂能够高效、高选择性地联合去除高砷（V）和高氟。吸附柱的饱和吸附容量可高达15mg/g干重，反复使用中饱和体积的相对标准偏差小于0.5%，柱处理出水的各项有关指标均符合我国生活饮用水卫生标准，特别是砷（V）的质量浓度低于0.010mg/L，符合世界健康组织（WHO）推荐的饮用水严格砷标准。说明该吸附剂在砷氟共存的地区具有很好的应用前景。     

泡沫铜电极电还原去除溴酸盐研究

电化学还原去除水中溴酸盐的研究表明,与石墨、碳纸及泡沫镍电极相比,泡沫铜电极对溴酸盐的去除效率较高.溴酸盐电化学还原速率随阴极电势降低先升高后降低.低pH条件下,溴酸盐电还原速率较高.初始溴酸盐浓度在50~350μg/L范围内,当阴极电势高于-1.5 V时,溴酸盐电还原过程受电子转移和溴酸盐扩散共同控制;当阴极电势小于-1.5 V时,溴酸盐的还原过程控速步骤主要是浓度扩散.溶解性有机物对溴酸盐电还原过程有明显的抑制作用.该电化学体系中,溴酸盐几乎彻底被还原为等量溴离子,溶液pH略有上升.自来水中溴酸盐的还原速率略低于去离子水.通过XPS分析了电化学还原反应前后泡沫铜电极上的Cu和O价态变化.     

二次微分简易示波伏安法测定酚磺乙胺

在0.2mol·L-1NaOH底液中,酚磺乙胺的氧化产物能够在示波图阴极支-0.3V处产生一个灵敏的切口,在一定的浓度范围内其二次微分简易示波伏安峰峰高随酚磺乙胺浓度的增大而线性增加,可用于酚磺乙胺片和注射液酚磺乙胺含量的测定.线性范围1.5×10-5～3.4×10-4mol·L-1,回归方程:h(V)=135.6+3.29×106C(mol·L-1),r=0.9921,检出限:6.0×10-6mol·L-1.对3.0×10-5mol·L-1酚磺乙胺5次测定的RSD为2.1%.与高效液相色谱及其他方法相比,本方法具有仪器简单、简便快速、无需通氮除氧等特点.     

DNA aggregation and cleavage in CGE induced by high electric field in aqueous solution accompanying electrokinetic sample injection

The phenomenon of peak area decrease due to high injection voltage (V_inj, e.g. 10–30 kV, 200–600 V/cm in the 50 cm capillary) was found in the analysis of very dilute DNA fragments (<0.2 mg/L) by using high‐sensitive electrokinetic supercharging‐CGE. The possibility of DNA cleavage in aqueous solution was suggested, in addition to the aggregation phenomenon that is already known. The analysis of intentionally voltage‐affected fragments (at 200 V/cm) also showed decreased peak areas depending on the time of the voltage being applied. Computer simulation suggested that a high electric field (a few kV/cm or more) could be generated partly between the electrode and the capillary end during electrokinetic injection (EKI) process. After thorough experimental verification, it was found that the factors affecting the damage during EKI were the magnitude of electric field, the distance between tips of electrode and capillary (D_e/c), sample concentration and traveling time during EKI in sample vials. Furthermore, these factors are correlating with each other. A low conductivity of diluted sample would cause a high electric field (over a few hundred volts per centimeter), while the longer D_e/c results in a longer traveling time during EKI, which may cause a larger degree of damage (aggregation and cleavage) on the DNA fragments. As an important practical implication of this study, when the dilute DNA fragments (sub mg/L) are to be analyzed by CGE using EKI, injection voltage should be kept as low as possible.     

锂离子电池LiTi_(0.25)Fe_(0.75)SO_4F正极材料的电子结构

采用密度泛函理论平面波赝势的方法,计算了LiFeSO_4F和LiTi_(0.25)Fe_(0.75)SO_4F正极材料的电子结构。计算结果表明:当锂嵌入材料后,S、O和F的原子布居变化较小,电子主要填充在过渡金属的3d轨道,导致过渡金属被还原,成为电化学反应的活性中心。在嵌锂态中,锂和氧(氟)之间形成了离子键,而过渡金属(Ti和Fe)与氧(氟)之间则形成了共价键,S-O键的共价性最强。态密度的计算结果则表明:Ti和Fe均保持高自旋排列结构;LiFeSO_4F的两个自旋通道的带隙分别为2.88和2.29 e V,其导电性很差;Ti掺杂使体系的带隙消失,显著地提高了正极材料的导电性;LiTi_(0.25)Fe_(0.75)SO_4F系统中Ti-O和Ti-F键均比纯相中的Fe-O和Fe-F键的共价性更强,因此Ti掺杂材料具有更好的结构稳定性。     

锂离子电池LiTi0.25Fe0.75SO4F正极材料的电子结构

采用密度泛函理论平面波赝势的方法,计算了LiFeSO₄F和LiTi_0.25Fe_0.75SO₄F正极材料的电子结构。计算结果表明：当锂嵌入材料后,S、O和F的原子布居变化较小,电子主要填充在过渡金属的3d轨道,导致过渡金属被还原,成为电化学反应的活性中心。在嵌锂态中,锂和氧（氟）之间形成了离子键,而过渡金属（Ti和Fe）与氧（氟）之间则形成了共价键,S-O键的共价性最强。态密度的计算结果则表明：Ti和Fe均保持高自旋排列结构;LiFeSO₄F的两个自旋通道的带隙分别为2.88和2.29 eV,其导电性很差;Ti掺杂使体系的带隙消失,显著地提高了正极材料的导电性;LiTi_0.25Fe_0.75SO₄F系统中Ti-O和Ti-F键均比纯相中的Fe-O和Fe-F键的共价性更强,因此Ti掺杂材料具有更好的结构稳定性。     

Effect of acid on morphology of calcite during acid enhanced defluoridation

Fluoride removal from water by lime materials is a promising defluoridation process. Acid enhanced limestone defluoridation (AELD) technique involves precipitation of CaF₂ as well as adsorption of fluoride on the surface of limestone which is capable of reducing fluoride concentration to below the WHO guideline value of 1.5 mg/L. Acids such as acetic acid and citric acid are added to the fluoride water before filtration through limestone column to enhance the Ca²⁺ activity in solution for precipitation of fluoride as CaF₂. This paper describes the effects of these acids on the quality of the limestone during the AELD process, which has been studied to evaluate the reusability of the limestone. The reaction products that formed during the AELD process have also been analyzed. The detail study of the morphology of the limestone before and after use have been done using various analytical techniques, viz., X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The study reveals that the limestone degrades to some extent in the process due to dissolution of calcium carbonate by the acids and adsorption of fluoride by the limestone. While appreciable quantity of the citrate salt of calcium was formed in the column, the acetate salt mostly remained dissolved in the water. Since mainly the surface of the limestone particles take part in the reaction, the limestone particles can be reused for the defluoridation process after cleaning the outer surface. The limestone after use remains also suitable as raw material for cement.     

Armor-like Inorganic-rich Cathode Electrolyte Interphase Enabled by the Pentafluorophenylboronic Acid Additive for High-voltage Li||NCM622 Batteries

Lithium metal batteries (LMBs) comprising Li metal anode and high-voltage nickel-rich cathode could potentially realize high capacity and power density. However, suitable electrolytes to tolerate the oxidation on the cathode at high cut-off voltage are urgently needed. Herein, we present an armor-like inorganic-rich cathode electrolyte interphase (CEI) strategy for exploring oxidation-resistant electrolytes for sustaining 4.8 V Li||LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) batteries with pentafluorophenylboronic acid (PFPBA) as the additive. In such CEI, the armored lithium borate surrounded by CEI up-layer represses the dissolution of inner CEI moieties and also improves the Li⁺ conductivity of CEI while abundant LiF is distributed over whole CEI to enhance the mechanical stability and Li⁺ conductivity compared with polymer moieties. With such robust Li⁺ conductive CEI, the Li||NCM622 battery delivered excellent stability at 4.6 V cut-off voltage with 91.2 % capacity retention after 400 cycles. The excellent cycling performance was also obtained even at 4.8 V cut-off voltage.     

Eliminating Voltage Decay of Lithium‐Rich Li1.14Mn0.54Ni0.14Co0.14O2 Cathodes by Controlling the Electrochemical Process

A lithium‐rich cathode material Li_1.14Mn_0.54Ni_0.14Co_0.14O₂ (LNMCO) is prepared by a co‐precipitation method. The issue of voltage decay in long‐term cycling is largely eliminated by control of the charge–discharge voltage range. The LNMCO material exhibits 9.8 % decay in discharge voltage over 200 cycles between 2.0–4.6 V, during which the working voltage decays significantly, from 3.57 V to 3.22 V. The decay was decelerated by a factor of six by using a voltage window of 2.0–4.4 V, from 3.53 V to 3.47 V. IR and Raman spectra reveal that the transformation of layered structure to spinel is significantly retarded under 2.0–4.4 V cycling conditions. Transmission electron microscopy (TEM) was also applied for examining phase change in an individual particle during cycling, showing that the spinel phase occurs both at 2.0–4.6 V and at 2.0–4.4 V, but is not dominant in the latter. Normalization of Li can remove the additional impact on the voltage decay which is brought by different amounts of Li intercalation. The mechanism of no voltage decay at 2.0–4.4 V cycling is raised and electrochemical impedance spectrum data also support the hypothesis.     

A19F NMR study of the anion mobility in lanthanum oxide fluorides

Conclusion All the oxide fluorides studied show intensive diffusion of the fluoride ions, and this is responsible for their high electrical conductivity. The anisotropy of the magnetic shielding of the fluorine nuclei in the rigid lattice has been determined from the field dependence of the second moment. In the high-temperature range, the anisotropy was measured from the form of the resonance line. The coincidence of the values of the anisotropy at high and low temperatures shows that in stoichiometric lanthanum oxide fluoride below the temperature of the phase transformation into the cubic modification, the fluoride ions move only through the equivalent positions of the fluorine sublattice. Analysis of the chemical shifts and their anisotropy shows that the movement of the fluoride ions has vacancy character. Above T_c, the exchange of positions with oxygen is possible. The behavior of the spectra in the intermediate range indicates high dynamic nonuniformity of the fluoride ions, brought about by the existence of regions with an increased fluorine mobility, which apparently have a structure similar to that of the nonstoichiometric lanthanum oxide fluorides with an increased fluorine concentration. The replacement of oxygen by fluorine at first leads to a sharp increase in the mobility of the fluoride ions (x=0.04), after which it has practically no influence up to x=0.143. It is not excluded that the increase in the mobility is related not to the excess of fluorine but to a rearrangement of the crystal structure. Judging from the behavior of the spectral lines in the intermediate range, nonstoichiometric lanthanum oxide fluorides are dynamically more uniform.L. V. Kirenskii Institute of Physics, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 24, No. 5, pp. 44–48, September–October, 1983.     

Studies on Synthesis and Electrochemical Performance of Li1+δNi1-xCoxO2-yFy Cathode Materials for Lithium-ion Rechargeable Batteries

It is a technological problem of LiNiO2 cathode material for lithium-ion secondary batteries because of the difficult preparation and hard purification, instable performance, remarkable capacity fading at initial discharge, worse thermal stability and safety of Ni-series cathode materials,and it is also the key factor of hindering LiNiO2 cathode material from practical applications.Recently, by doping some metal cations such as Co, Mn, Mg, Al, Cr and so on[1-5] into LiNiO2, the preparation difficulty and the purification hardness can be obviously improved, and the initial irreversible discharge capacity can be reduced, and the ratio of the initial discharge to charge capacity can be enhanced. But the cyclic stability, thermal stability and safety of LiNiO2 are not enough to satisfy the demand of commercial use.At present, the synthesis of LiNiO2 cathode material must be sintered under oxygen atmosphere in most cases, and the improved effect of fluoride doping on the electrochemical properties of LiNiO2 has seldom been reported in the literatures.In this paper, the cobalt cation and fluorine anion co-doping cathode materials Li1+δNi1-xCoxO2-yFy( 0≤δ≤0.2, 0≤x≤0.5, 0≤y≤0.1 ) were synthesized by solid state reaction method at 650℃ ～750℃ under air atmosphere, and characterized by XRD、 SEM、 TEM、 BET、 laser particle-size distribution measurement and electrochemical performance testing, the effect of different nickel sources on the properties of as-synthesized cathode materials was investigated. The results demonstrated that the cobalt and fluorine ions co-doping cathode materials Li1+δNi1-xCoxO2-yFy have complete layered structure, uniform surface morphology and better particle-size distribution as well as excellent electrochemical performances. At 20～25℃, 0.15～0.25mA charge and discharge current,4.25～2.70V cut-off voltage, 0.2～0.5C charge and discharge rate and 0.2～0.5 mA/cm2 current density,LiNi0.8Co0.2O1.95F0.05 cathode material has higher initial charge and discharge capacity and better cyclic properties which can be mainly attributed to the doping of the higher electronegativity fluorine which improves the structural stability and the synergistic reaction of cobalt and fluorine ions co-doping on the cathode materials. Under the above conditions, the initial charge and discharge capacity of LiNi0.8Co0.2O1.95F0.05 is 165.70mAh/g and 146.10mAh/g, respectively. After 50 cycles, it has more than 140mAh/g of discharge capacity and displays preliminary application possibility in the future.     

Electrolysis of ammonia for hydrogen production catalyzed by Pt and Pt-Ir deposited on nickel foam

Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic curves. The low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water (1.6 V), can be obtained at a current density of 2.5 mA/cm². Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H₂ produced can be estimated.     

Bifunctional o-CoSe2/c-CoSe2/MoSe2 heterostructures for enhanced electrocatalytic and photoelectrochemical hydrogen evolution reaction

The bottleneck of alkaline hydrogen evolution reaction lies in the kinetically sluggish brought from multistep reaction processes involving water adsorption and dissociation, as well as hydrogen adsorption. In this work, we successfully synthesized o-CoSe₂/c-CoSe₂ heterostructures anchored on MoSe₂ nanosheets to powerfully promote reaction processes. As an electrocatalyst, it exhibits a low overpotential of 112 mV at 10 mA/cm² and a Tafel slope of 96.9 mV/dec for an alkaline hydrogen evolution reaction. Moreover, the as-prepared catalyst can behave as both cathode and anode for overall water splitting, which only requires 1.61 V cell voltage at 10 mA/cm². Significantly, the cell voltage can be further reduced to 1.53 V at 10 mA/cm² for water electrolysis under the simulated solar irradiation owing to such a semiconductor-based heterostructure that facilitates the separation of photogenerated charges. Here, the improving overall performance of this ternary electrocatalyst is attributed to the multifunctionality and synergistic interaction of different components in this heterogeneous material. The work provides a novel strategy to design active catalysts simultaneously using electric energy and solar energy for effective water splitting.