热补偿恒温控制条件下铂电极BZ反应体系中的电化学时间自组织——从极限环型电化学振荡到环面跳跃型非连续电化学振荡

在实验室的热补偿恒温控制条件下, 理论预测的等温恒电流(电压)电化学振荡实际上将发生变异. 用慢流型上准定态的线性化稳定性分析法全面分析了此类恒温控制条件下铂电极BZ反应系在以温度为慢变参数的慢流型上的准稳定性及绕温度轴慢变轨迹的动力学行为. 发现在温度围绕控制值上下往复波动的每一个周期内, 准定态点将穿梭跨越于振荡区与非振荡区之间, 表现为间隙性的沿温度轴的环面型电化学振荡. 计算机模拟结果证实了上述理论分析.     

铂电极BZ反应体系的系统动力学分析

在一定的条件下,将铂电极BZ化学反应的六变量高维动力学系约化为三变量体系,同时对该体系进行了全面的系统动力学分析.研究结果表明,通过改变耦合体系的外控参数条件,在将体相保持在均一稳定定态的参数范围内,电极反应相可能进入振荡区,而呈现出电极反应相与体相的动力学行为不一致性.进一步计算出体相处于非振荡状态时,电极反应相产生电化学振荡的外控参数区域.     

外控恒电流对BZ电化学反应体系动力学行为的影响

在使用探头对BZ反应体系进行观测时,原来纯粹的BZ反应系变成了由两个子系通过扩散过程耦合成的一类特殊电化学体系,所用的探头能否如实反映该体系的真实振荡行为值得探讨。本文基于FKN机理及Oregonator模型,分别对Pt电极BZ反应体系建立了动力学模型,讨论了两子系出现极限环振荡的动力学行为不一致性及外控电极电流的影响。     

外控弱周期电流约束下电极B-Z反应体系中的时间自组织

The coupled dynamical model consisting of the electrode B-Z system, and its related bulk phase B-Z system externally controlled by a periodical current is proposed on the basis of the Oregonator model. Dynamical behaviors of the electrode B-Z system, when subjected to external current constraint have been investigated systematically under the condition that the bulk phase is at a steady state. Furthermore, by means of the analytic method of slow manifold the regimes favorable to the appearance of limit-cycle oscillation have been determined on both the current~concentration of BrO3- and the current~model parameter plane respectively. The results are similar to those of experiments controlled externally by weak-periodical potential constraint, as reported in former works. It turns out that a limited cycle oscillatory regime degenerates under external periodical current constraint. Meanwhile, a kind of forced oscillations emerges in the regime where limit-cycle oscillations can t appear under constant current constraint.     

Thermokinetic Behaviour Degenerated from Limit Cycle Oscillation of Isothermal B-Z Reaction System due to Temperature Controlling of Heat Compensation Type

The thermokinetic behavior of the B-Z reaction system was influenced by both the chemical reaction-heat conduction coupling and the temperature undulation due to temperature controlling of heat compensation type. Quantitative research indicated that this kind of temperature fluctuation will lead to limit cycle degeneration and the periodic or quasi-periodic response behavior of the focus near a supercritical Hopf bifurcation.     

Location of Chemical Reaction of Indirect Electrochemical Synthesis in a Porous Hydrophobized Electrode

Location of chemical reaction of IES performed in a porous hydrophobized electrode is considered. Depending on the rate constant and order of the reaction, it can proceed in the electrode's porous space and in the electrolyte chamber.     

电化学浸渍法制备空间氢镍电池用镍电极的循环寿命研究

以空间储能电源4.5＇镍极板为对象,研究了过充电、高倍率及极板孔径对电化学浸渍电极循环寿命的影响.结果表明,5C过充电70%,电极初始容量为2.7 Ah,150次循环后容量逐渐下降,300次循环,放电容量约为1.7 Ah（保持率约63%）.5C无过充电,300次循环其容量保持率约100%,1000次循环,容量保持率仍可达76%.无过充电,极板孔径及小电流活化均可改善电极循环性能.     

铂电极BZ反应系双电层稀疏区中的Turing结构

将扩散流作为场函数, 考虑φ电势的空间分布, 建立了铂电极BZ反应系在双电层稀疏区的动力学演化机制, 确立了纳入稀疏区φ电势效应的反应-扩散型演化方程. 采用Boltzmann分布近似, 解决了演化方程中含φ电势的流项的线性化问题; 导出了可在算法上实现的三变量体系线性化算子本征值的解析形式. 分别以静态铂电极BZ反应系双电层稀疏区和对应的纯粹BZ反应系作为参考模型系, 分析了经空间对称性破缺产生Turing结构的参数范围. 数值模拟发现, φ电场的存在使铂电极BZ反应系的输运过程在静态双电层稀疏区趋于电化学平衡时, 在对应的纯粹BZ反应体系中可呈现的Turing结构已趋于消失; 而在电流强度不太大的恒流不可逆铂电极BZ反应体系双电层稀疏区中, 鲜明稳定的Turing结构又重新出现在原参数区间内. 同时, 在静态双电层稀疏区不出现Turing结构的参数范围内也可找到类似的恒流稳定空间结构.     

物理化学实验改进:修饰的BZ化学振荡反应在食品检测中的应用*

为适应创新应用型人才培养的需要,针对现有物理化学实验教材中的BZ振荡反应实验进行了验证-探索两段式教学尝试。在保留原有验证性实验基础上进行延伸,探索催化剂、反应底物的浓度对碘离子修饰的BZ振荡体系的影响,绘制了罗丹明B的标准曲线,用以检测食品中罗丹明B的含量。相比传统验证性实验,两段式教学模式更易于课上、课下相结合,既能训练学生物理化学基本实验技能,又有利于学生自主创新能力和科研能力的培养。     

Effect of Surface Impurities on Oscillation in NO+CO/Pt(100) Reaction System

A lattice gas model was proposed to explore the effect of inert surface impurities on the oscillation in the NO+CO reaction system on Pt(100). It was found that when the fraction of the impurities is small, the (1*1) phase resulting from the surface restructuring can form a connected phase and the system exhibits a global sustained oscillation. With the fraction of the impurities increasing, the (1*1) phase only can form many isolated patches and the spatial coherence between the local oscillators with a random phase relationship lost, and as a result, the sustained oscillation changes into a damped one. When the diffusion rate of adsorbed CO and NO increases, the synchronization between local oscillators is enhanced and the global sustained oscillation can appear again.     

Thermokinetic Oscillation of a Two-step Reacting System Coupled with Thermal Conduction and Apparent Uncertainty in the Phenomenological Kinetic Measure of Unimolecular Reactions

A nonisothermal two-step mechanism for a unimolecular reaction coupled with thermal conduction is suggested in this paper. The stability of the relevant thermokinetic steady states was investigated by means of linear stability analysis.     

苯酚的敞开体系化学振荡反应动力学法测定

利用KBrO3-Ce(SO4)2-Ch2(COOH)2-H2SO4敞开体系研究测定黄河水中苯酚污染物的新方法,在连续搅拌反应器（CSTR）中,当[KBrO3]=0.0625mol/L,[CH2(COOH)2]=0.187mol/,[Ce(SO4)2]=0.002mol/,[H2SO4]=0.8mol/L,蠕动泵单路流速为1.2mL/min时,苯酚的质量浓度在0.10-25mg/L范围内与振幅的改变、周期的改变呈线性关系,检出限为0.05mg/L;苯酚的加标回收率为95%-102%。     

毛细管电泳-电化学检测法测定硫酸铜-维生素C反应体系中的羟基自由基和菊花的抗氧化活性

采用毛细管电泳-电化学检测方法,以对羟基苯甲酸为自由基捕捉剂,测定了硫酸铜-维生素C反应体系(pH 7.4)中生成的羟基自由基。研究了电极电位、运行液的pH值、电泳电压及进样时间对体系中反应物和产物分离的影响,得到了最优化的测定条件;讨论了体系中各反应物浓度和反应时间对产物浓度的影响。以直径为300 μm的碳圆盘电极为检测电极,工作电极电位为0.95 V(vs.SCE),目标产物3,4-二羟基苯甲酸在1.5×10-4~6.0×10-6 mol/L范围内线性关系良好,检测限（S/N=3）为1.5×10-6 mol/L。应用该方法,研究测定了不同品种菊花的抗氧化活性。