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共有20条相似文献,以下是第1-20项 搜索用时 187 毫秒

1.  Impedance Studies of Spinel LiMn2O4 Electrode/electrolyte Interfaces  
   ZHUANG Quan-chao  FAN Xiao-yong  XU Jin-mei  WEI Guo-zhen  DONG Quan-feng  SUN Shi-gang《高等学校化学研究》,2008年第24卷第4期
   The formation process of solid electrolyte interphase(SEI) film on spinel LiMn2O4 electrode surface was studied by electrochemical impedance spectroscopy(EIS) during the initial storage in 1 mol/L LiPF6-EC:DMC:DEC electrolyte and in the subsequent first charge-discharge cycle. It has been demonstrated that the SEI film thickness increased with the increase of storage time and spontaneous reactions occurring between spinel LiMn2O4 electrode and electrolyte can be prevented by the SEI film. In the first charge-discharge cycle succeeding the storage, the electrolyte oxidation coupled with Li-ion insertion is evidenced as the main origin to increase the resistance of SEI film. The results also confirm that the variations of the charge transfer resistance(Rot) with the electrode potential(E) can be well described using a classical equation.    

2.  Theoretical Investigation of a Single Molecule Device: Geometrical Configurations and Electronic Properties  
   袁喆 苏长荣 张世忠 李家明《中国物理快报》,2004年第21卷第3期
   Using the first-principle molecular dynamics simulations, we have studied the molecular geometrical configurations as well as the corresponding electronic structures of a single molecule device assembled by the mechanically controllable break junction technique with variations of the electrode distance. There are some very interesting features varying with the electrode distance.    

3.  Simulation of Inelastic Electron Tunnelling Spectroscopy on Different Contact Structures in 4,4'-Biphenyldithiol Molecular Junctions  被引次数:1
   邹斌 李宗良 宋秀能 王传奎《中国物理快报》,2008年第25卷第1期
   A first-principles computational method is developed to study the inelastic electron tunnelling spectroscopy (IETS) of 4,4'-biphenyldithiol molecular junction with three different contact structures between the molecule and electrodes in the nonresonant regime. The obtained distinct IETS can be used to resolve the geometrical structure of the molecular junction. The computational results demonstrate that the IETS has certain selection rule for vibrational modes, where the longitudinal modes with the same direction as the tunnelling current have greatest contribution to the IETS. The thermal effect on the IETS is also displayed.    

4.  Electronic Transport in Molecular Junction Based on C20 Cages  
   欧阳芳平 徐慧《中国物理快报》,2007年第24卷第4期
   Choosing closed-ended armchair (5, 5) single-wall carbon nanotubes (CCNTs) as electrodes, we investigate the electron transport properties across an all-carbon molecular junction consisting of C20 molecules suspended between two semi-infinite carbon nanotubes. It is shown that the conductances are quite sensitive to the number of C20 molecules between electrodes for both configuration CF1 and double-bonded models: the conductances of C20 dimers are markedly smaller than those of monomers. The physics is that incident electrons easily pass the C20 molecules and are predominantly scattered at the C20-C20 junctions. Moreover, we study the doping effect of such molecular junction by doping nitrogen atoms substitutionally. The bonding property of the molecular junction with configuration CF1 has been analysed by calculating the Mulliken atomic charges. Our results have revealed that the C atoms in N-doped junctions are more ionic than those in pure-carbon ones, leading to the fact that N-doped junctions have relatively large conductance.    

5.  Interfaces in ionic devices  
   Werner Weppner《Ionics》,2001年第7卷第4-6期
   The technology of Ionics is based on the availability of materials with fast ion transport. Individual materials are, however, meaningless from a practical point of view; all applications require combinations of materials with appropriate ionic and electronic properties. This situation is similar to Electronics which requires combinations of semi-conducting or metallic conducting materials with differences in the chemical potentials of the electrons. The technology of Ionics requires interfaces between ionic and electronic conductors which generate strong electrical fields or allow to modify the field by the application of external voltages. Ions and electrons equilibrate both at these “ionic junctions”. While semi-conductor junctions have commonly a width in the μm-range, the space charge region is several orders of magnitude smaller in the case of ionic junctions, i.e. in the nm or even sub-nm-range. The interfaces have to be chemically stable for the lifetime of the device which is difficult to achieve in view of the commonly large number of components present in both phases and the existence of mobile species with sometimes large variations in the activity of the electroactive component. Furthermore, the kinetics of transfer of ions across the interface has to be fast to allow high current densities which are required in many cases. In addition, two such interfaces are required to convert the electronic current into an ionic one and again back into an electronic current at the opposite side of the electrolyte. The development of ionic devices depends to the strongest extent on the engineering of appropriate interfaces. Examples of the role and engineering of interfaces will be presented for applicationes such as chemical sensors, electrochromic devices, fuel cells, batteries and photogalvanic solar cells.    

6.  Theory and application of cyclic voltammetry for measurement of fast electrode kinetics at microdisk electrode  
   JIN  Bao-Kang ZHANG  Jian-Rong ZHANG  Zu-XunDepartment of Chemistry  Nanjing University  Nanjing  Jiangsu 210093  China《中国化学》,1996年第4期
   An analytical expression describing voltammetric behaviors responses at microdisk electrode for various diffusion conditions and degrees of reversibility is reported in this paper. Results of theoretical calculation made it possible to use cyclic voltammetry to evaluate heterogeneous rate constants under intermediate diffusion conditions. At relatively low scan rate, the distortion of current-voltage can be reduced due to small iR drops and charging current. The effects of transfer coefficient, a, kinetic parameter, (=k0r/4D), and switching potential, s, on potential peak separation are discussed in detail. The relationship obtained in this paper between potential peak separation and \ is in good agreement with that in Ref. 14, whose authors have got their results by using digital simulation technique. After the experiment of Fe(CN)64- oxidation, k0 and a were obtained by the theory of this paper. The result agrees with that in Ref. 19.    

7.  Electrochemical characteristics of poly(ophenylendiamine) film electrodes in phosphatic solution  
   YE  Bao-Xian ZHANG  Wu-Ming ZHOU  Xing-YaoDepartment of Chemistry  Wuhan University  Wuhan  Hubei 430078  China《中国化学》,1997年第4期
   The electrochemical characteristics of poly(o-phenylendiamine) (POPD) film modified electrodes have been investigated using different electrochemical techniques.The main interest is focused on the effect of potential and film thickness on the electrode process.Good agreement has been found for the apparent diffusion coefficient estimated by chronocoulometry and impedance spec-troscopy.The charge transfer process within POPD films is diffusion processes at negative and positive overpotentials and electron hopping mechanism at formal potential.The POPD film conductivity of the oxidized state is better than that of the reduced state.For all electrode processes,the H+ may penetrate the film/electrolyte interface and take part in charge transfer or protonation-deprotonation of phenazine rings.    

8.  Classical simulation of atomic beam focusing and deposition for atom lithography  
   陈献忠  姚汉民  陈旭南《中国光学快报(英文版)》,2004年第4期
   We start from the intensity distribution of a standing wave (SW) laser field and deduce the classical equation of atomic motion.The image distortion is analyzed using transfer function approach. Atomic flux density distribution as a function of propagation distance is calculated based on Monte-Carlo scheme and trajectory tracing method.Simulation results have shown that source imperfection,especially beam spread, plays an important role in broadening the feature width,and the focus depth of atom lens for real atomic source is longer than that for perfect source.The ideal focal plane can be easily determined by the variation of atomic density at the minimal potential of the laser field as a function of traveling distance.    

9.  Electric Field Analysis of Space Charge Injection from a Conductive Nano-Filler Electrode  
   肖春  张冶文  郑飞虎  魏雯婕《中国物理快报》,2010年第27卷第7期
   A simulation on the electric field distribution near the electrode is proposed to explain the reason for using nanosized carbon black mixed with ethylene vinyl acetate, as the electrode could lead to more charge injection into the polymer than using a deposited metal electrode. The electrode is simplified to a layer of conductive semi-spheres with fixed size and constant electric potential. By using the finite element method, it is found that both the size of the semi-spheres and the distance between adjacent semi-spheres could dramatically influence the electric field near the surface of the spheres; these are considered to be the two decisive factors for the charge injecting rate at electrodes of various materials.    

10.  One-step synthesis of Pt nanoparticles/reduced graphene oxide composite with enhanced electrochemical catalytic activity  
   CHEN Chen  LONG MingCe  WU HaoDong  CAI WeiMin《中国科学:化学(英文版)》,2013年第56卷第3期
   A one-step electrochemical approach for synthesis of Pt nanoparticles/reduced graphene oxide(Pt/RGO) was demonstrated.Graphene oxide(GO) and chloroplatinic acid were reduced to RGO and Pt nanoparticles(Pt NPs) simultaneously,and Pt/RGO composite was deposited on the fluorine doped SnO 2 glass during the electrochemical reduction.The Pt/RGO composite was characterized by field emission-scanning electron microscopy,Raman spectroscopy and X-ray photoelectron spectroscopy,which confirmed the reduction of GO and chloroplatinic acid and the formation of Pt/RGO composite.In comparison with Pt NPs and RGO electrodes obtained by the same method,results of cyclic voltammetry and electrochemical impedance spectroscopy measurements showed that the composite electrode had higher catalytic activity and charge transfer rate.In addition,the composite electrode had proved to have better performance in DSSCs than the Pt NPs electrode,which showed the potential application in energy conversion.    

11.  掺杂纳米金粒子的火焰氧化TiO2膜的光电化学性质的研究  
   徐红  刘玲  贾能勤  杨洁  严曼明  江志裕《中国化学》,2005年第23卷第1期
   A nano-Au modified TiO2 electrode was prepared via the oxidation of Ti sheet in flame and subsequent modification with gold nanoparticles. The results of SEM and TEM measurements show that the Au nanoparticles are well dispersed on TiO2 surface. A near 2-fold enhancement in photocurrent was achieved upon the modification with Au nanoparticles. From the results of photocurrent and electrochemical impedance experiments it was found that the flatband potential of nano-Au/TiO2 electrode negatively shifted about 100 mV in 0.5 mol/L Na2SO4 solutions compared with that of bare TiO2 electrode. The improvement of photoelectrochemical performance was explained by the inhibition for charge recombination of photo-induced electrons and holes, and the promotion for interracial charge-transfer kinetics at nano-Au/TiO2 composite film. Such nanometal-semiconductor composite films have the potential application in improving the performance of photoelectrochemical solar cells.    

12.  Energy relationship and the polarization of C_(60) cage in the endohedral complexes (X@C_(60))  
   徐志瑾  朱传宝  严继民《中国化学》,1998年第3期
   In this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Kb, Cs; F, Cl, Br, I), where the position of X changes along 5 typical symmetry directions. For the calculation of quantum chemistry we use EHMO/ASED method, for the calculation of molecular mechanics we use Buckingham potential (exp-6-1) function, and for the calculation of thermo-chemical cycle we use individually isolating the processes such as the structure variation, charge transfer and charge distribution, and their interactions etc. The calculation results show that (1) In the region of radius r≈0.2 nm of the Ceo cage, the potential field is nearly spherical; (2) Except for Li and Na, the systems are the most stable with minimum energies at the center of C60 cage. For Li and Na, the systems are the most stable with minimum energies at r≈0.16 nm and r≈0.13 nm, respectively. In view of the interactive region of chemical bonds, the interactions between X and the C60 cage do not belong to the classical chemical bonds; (    

13.  Electrocatalytic oxidation of NADH at glassy carbon electrodes modified with an electropolymerized film of nile blue A  被引次数:1
   蔡称心  薛宽宏《中国化学》,2000年第2期
   The kinetic parameters for the electrocatalytic oxidation of di-hydronicotiamide adenine dinucleotide (NADH) at glassy carbon electrodes modified with an electropolymerized film of nile blue A (PNB) have been determined based on rotating disk electrode measurements. The rate constant for the chemical reaction between NADH and PNB is strongly influenced by NADH concentration and the pH value of solution, and it decreases with increasing NADH concentration, indicating that the electrocatalytic process proceeds via the formation of an intermediate of charge-transfer complex between NADH and PNB.    

14.  A molecular dynamics study of the structural change differences between Au225 and Au369 clusters on MgO surfaces at low temperature  
   张林  王绍青  陈难先《中国物理 B》,2012年第3期
   The differences in structural change between Au 225 and Au 369 clusters with their(111) facets supported on MgO(100) surfaces at 5 K are studied by using molecular-dynamics simulations with the atomic interchange potentials of the Au/MgO interface.The parameters are obtained from the ab initio energies using the Chen-Mo¨bius inversion method.Analyses of the pair distribution functions show that the two Au clusters use different deformation processes to adjust the distances between the interface atoms,owing to the misfit between the atom distances among the clusters and the substrates.The local structural changes are identified by atomic density profiles.    

15.  Theoretical Study on the Charge Transport Properties of Coronene and Its Derivatives  
   蔡静  胡競丹  徐布一  李权  赵可清《结构化学》,2009年第28卷第7期
   Molecular structures, reorganization energies and charge transport matrix elements of coronene and its fluoro-, hydroxyl- and sulfhydryl-substituted derivatives have been studied at the B3LYP/6-31G** level. Based on the semi-classical model of electron transfer, charge transport rate constants of the title molecules have been calculated. The results indicate that the coronene molecule is helpful to the transport of negative charge, and the transport rate of positive charge is between those of hexaazatriphenylene and triphenylene.    

16.  Investigation of Co304 nanorods supported Pd anode catalyst for methanol oxidation in alkaline solution  
   《天然气化学杂志》,2014年第6期
   A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3-5 nm) are uni- formly deposited onto the surface of Co304 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of log/against logv reveals that MEO on Pd-CO304 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-CO304 is observed at -0.05 V, which coincides with the potential of MEO peak.    

17.  Promising supercapacitor electrodes based immobilization of proteins onto macroporous Ni foam materials  
   Mohamed Khairy  Sherif A.El-Safty《天然气化学杂志》,2015年第1期
   Immobilizing biocomponents on solid surfaces is a critical step in the development of new devices for future biological, medical, and electronic applications. Therefore, numerous integrated films were recently developed by immobilizing different proteins or enzymes on electrode surfaces. In this work, hemeproteins were safely immobilized onto macroporous nickel-based electrodes while maintaining their functionality.Such modified electrodes showed interesting pseudo-capacitive behavior. Among hemeproteins, hemoglobin(Hb) film has a higher electrochemical performance and greater charge/discharge cycling stability than myoglobin(Mb) and cytochrome C(Cyt C). The heme group in an alkaline medium could induce the formation of superoxides on the electrode surface. These capacitive features of hemeprotein-Ni electrode were related to strong binding sites between hemeproteins and porous Ni electrode, the accumulation of superoxide or radicals on the Ni surface, and facile electron transfer and electrolyte diffusion through the three-dimensional macroporous network. Thus, these new protein-based supercapacitors have potential use in free-standing platform technology for the development of implantable energy-storage devices.    

18.  Electron Holography of Barrier Structures in Co/ZrAlOx/Co Magnetic Tunnel Junctions  
   张喆 朱涛 沈峰 盛雯婷 王为刚 肖强 张泽《中国物理快报》,2005年第22卷第7期
   We investigate the potential profiles and elemental distribution of barriers in Co/ZrAlOx/Co magnetic tunnel junctions (MTJs) using electron holography (EH) and scanning transmission electron microscopy. The MTJ barriers are introduced by oxidizing a bilayer consisting with a uniform 0.45-nm Al layer and a wedge-shaped Zr layer (0-2 nm). From the scanning transmission electron microscopy, AlOx and ZrOx layers are mixed together, indicating that compact AlOx layer cannot be formed in such a bilayer structure of barriers. The Eli results reveal that there are no sharp interfaces between the barrier and magnetic electrodes, which may be responsible for a smaller tunnelling magnetoresistance compared with the MTJs of Co/AlOx/Co.    

19.  The effect of electric charge on the mechanical properties of graphene  
   HAO Peng  GAO YuanWen  ZHOU YouHe《中国科学:物理学 力学 天文学(英文版)》,2013年第6期
   The effect of electric charge on the mechanical properties of graphene under tensile loading is investigated by using molecular dynamics method.A modified atomistic moment method based on the classical electrostatics theory is proposed to obtain the distribution of extra charges induced by an external electric field and net electric charges stored in graphene.The electrostatic interactions between charged atoms are calculated using the coulomb law.The results show that the Young’s modulus and the critical fracture stress under uniaxial tension decrease with the increase of electric potential and net charges on graphene.The failure of graphene induced by electric charges is found to be controlled by charge level.The results indicate that the carbon-carbon bonds at the edge of graphene will break first.    

20.  Energy band alignment at ferroelectric/electrode interface determined by photoelectron spectroscopy  
   陈峰  吴文彬  李舜怡  Andreas Klein《中国物理 B》,2014年第23卷第1期
   The most important interface-related quantities determined by band alignment are the barrier heights for charge transport, given by the Fermi level position at the interface. Taking Pb(Zr,Ti)O3(PZT) as a typical ferroelectric material and applying X-ray photoelectron spectroscopy(XPS), we briefly review the interface formation and barrier heights at the interfaces between PZT and electrodes made of various metals or conductive oxides. Polarization dependence of the Schottky barrier height at a ferroelectric/electrode interface is also directly observed using XPS.    

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