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1.
应用光脉冲技术借助计算机由FFT运算测定了n-InP在Fe~(3+)/Fe~(2+)溶液中复收集率图,结果为一第四象限内半园,由理论模型从园心位置、园半径及特征频率可算出三个动力学参数;研究了电极电位及光强对这些参数的影响,并对结果进行了讨论。  相似文献   

2.
《电化学》2017,(6)
采用线性扫描伏安法和循环伏安法研究了含有Cl~-、SO_4~(2-)的酸性溶液中Fe~(2+)/Fe~(3+)相互转换对电极反应和Fe~(3+)还原过程的影响.结果表明,[Fe]T=1 mol·L~(-1)条件下,溶液中Fe~(3+)/Fe~(2+)的还原析出过程经过两个阶段:1)E=0.35 V左右Fe~(3+)还原成Fe~(2+)过程;2)E=-0.3 V之后H+的还原,同时Fe~(2+)离子与OH-相结合生产Fe(OH)_2;Fe~(3+)/Fe~(2+)的相互转化主要影响Fe~(3+)的第一还原阶段的还原峰电流和峰电位.|ipa/ipc|值随c(Fe~(3+))/c(Fe~(2+))的增大而增大,且扫描速率慢时影响大,扫描速率快时影响小;0.50 mol·L-1Fe~(2+)+0.50 mol·L-1Fe~(3+)时,随扫描速率的变化|ipa/ipc|值变化最小(|ipa/ipc|≈1.20).同时,c(Fe~(3+))/c(Fe~(2+))也影响着平衡电位,平衡电位随c(Fe~(3+))/c(Fe~(2+))增大而正移,电位从E1=0.501 V升至E5=0.565 V.  相似文献   

3.
应用光脉冲技术借助计算机由FFT运算测定了n-InP在Fe~(3+)/Fe~(2+)溶液中复收集率图, 结果为一第四象限内半园, 由理论模型从园心位置、园半径及特征频率可算出三个动力学参数; 研究了电极电位及光强对这些参数的影响, 并对结果进行了讨论。  相似文献   

4.
近年来,一些作者测定了半导体电极的复阻抗,而n-InP的复阻抗至今未见报道。本文测定了n-InP在Fe~(3 )/Fe~(2 )溶液中的复平面图,它在低频区为一直线,应用Randles频谱图,证明其符合混合控制机理,研究了电极电位及光强对频谱图的影响,并用理论模型对实验结果进行了解释。理论部分n型半导体当电极电位负于平带电位时,表面为反型层,则氧化剂阴极还原过程为O ne→R若反应完全不可逆,则电流密度J符合下列关系式:  相似文献   

5.
贵刊1987年第3期刊登的“鉴别 Fe~(2+)离子和 Fe~(3+)离子方法14种”一文,有几处不妥的地方,提出一点看法,以便商讨。一、二氧化硫法将 SO_2分别通入含 Fe~(2+)和 Fe~(3+)的溶液中,该文所叙述的现象和反应方程式,是错误的。1.从实验的角度讲,将 SO_2通入含 Fe~(2+)的溶液中并无浅黄色浑浊出现。为此,我又作了专门的验证实验,发现溶液中既无硫沉淀,也无 FeSO_(?)沉淀,(因溶液绝对呈酸性。)溶液也未呈褐黄色。2.从理论上讲,依电极电位(酸性介质):H_2SO_3+4H~++4e(?)S↓+3H_2OE~0=0.45伏Fe~(3+)+e(?)Fe~(2+) E~0=0.770伏显然,E~0H_2SO_3/S E~0Fe~(3+)/Fe~(2(?)),说明在酸性条件下,只能是 Fe~(3+)将 S 氧化为 H_2SO_3,而不  相似文献   

6.
本文主要研究了双组份离子共存体系的竞争还原容量、竞争反应动力学、影响竞争的各种因素以及竞争反应产物在活性碳纤维表面的形态。实验结果表明,在双组份离子体系中,活性碳纤维优先与电极电位高者反应,当两组份电极电位均较高时,两者先后都可与活性碳纤维反应,而两组份电极电位一高一低时,只有高电极电位离子能与活性碳纤维反应。当Au~(3+)与Fe~(3+)、Hg~(2+)等电极电位较低的离子共存时,活性碳纤维对Au~(3+)具有高度的选择还原特性。反应条件一般不改变离子参与反应的顺序。活性碳纤维制备工艺对产品的电极电位分布及选择反应特征没有本质上的影响。Hg~(2+)、Fe~(3+)的存在会影响Au在活性碳纤维表面的结晶形态。  相似文献   

7.
本文测定了不同电位及不同光强下, n-InP在Fe~(3+)/Fe~(2+)溶液中的复阻抗图, 从一个等放电路用计算机对结果进行了拟合, 并对拟合结果进行了讨论。  相似文献   

8.
空白试验证明,用浓度大于1mol/L的盐酸溶液做Fe~(3+)的提取液,或用过浓盐酸溶液酸化试液,盐酸中的Fe~(3+)都会给检验试液中的Fe~(3+)带来干扰;检验食品中的铁元素时,若铁是以Fe~(2+)形式存在,如果加入硝酸将其氧化为Fe~(3+),硝酸中Fe~(3+)会对检验试液中的Fe~(3+)带来干扰。  相似文献   

9.
用恒电位下电流衰减和动电位扫描方法研究了锌电极在KOH溶液中阳极溶解过程的中间吸附步骤;用旋转圆盘电极动电位扫描法考察了不同扫描速度下传质过程的影响。在接近于锌的阳极活性溶解的电位区,在恒电位下,衰减的电流的对数lgi与时间t呈线性关系,在电流降落的最初350ms的时间内,这一直线的斜率?lgi/?t与氢氧根离子浓度[OH~(-1)]成直线关系。在随后的350ms至1000ms的时间内,直线的斜率(?lgi/?t)’与  相似文献   

10.
(一)前言螯合电位滴定是电位滴定的一个主要组成部分,文献极为丰富。这些滴定主要是在金属电极和离子选择电极上进行的。金属电极分为两类:配偶型和非配偶型。配偶型电极如Pt/Fe~(3+);Fe~(2+)、Hg/Hg~(2+);HgY~(2-);MY~(n-4)M~(n+),其“电极/溶液”界面上总有一对决定电位的电对。非配偶型电极的界面上则不存在明显的电对,如铂电极上EDTA滴定Ca~(2+),溶液中不外加高价的铂离子;滴定Fe~(3+),也不外加Fe~(2+)。关于非配偶型电极上的螯合滴定,虽有  相似文献   

11.
应用小信号电流阶跃法研究了光照下n-InP/Fe~(3+), Fe~(2+)界面, 此时电位变化符合双指数规律, 这和理论推导是一致的。在时间很短时, 电位与时间成线性关系, 从直线斜率可求出空间电荷区电容。  相似文献   

12.
用微分电容法及强光照开路电位法研究了电解质溶液的pH、氧化还原对、交流电频率、n-InP晶面及表面处理对其液结界面平带电位的影响,并测定了n-InP半导体电极的一些参数.  相似文献   

13.
In this work, the tunneling breakdown of n-InP electrode using large signal current density step has been investigated. The influence of current density on the tunneling breakdown is not obvious, but the light intensities affect the breakdown severely. Some parameters are calculated during breakown and explained.  相似文献   

14.
An electrochemical approach to fabricate a nanostructured Fe/Pt-Fe catalyst through electrodepo-sition followed by galvanic replacement is presented. An Fe/Pt-Fe nanostructured electrode was prepared by deposition of Fe-Zn onto a Fe electrode surface, followed by replacement of the Zn by Pt at open-circuit potential in a Pt-containing alkaline solution. Scanning electron microscopy and energy-dispersive X-ray techniques reveal that the Fe/Pt-Fe electrode is porous and contains Pt. The electrocatalytic activity of the Fe/Pt-Fe electrode for oxidation of methanol was examined by cyclic voltammetry and chronoamperometry. The electrooxidation current on the Fe/Pt-Fe catalyst is much higher than that on flat Pt and smooth Fe catalysts. The onset potential and peak potential on the Fe/Pt-Fe catalyst are more negative than those on flat Pt and smooth Fe electrodes for methanol electrooxidation. All results show that this nanostructured Fe/Pt-Fe electrode is very attractive for integrated fuel cell applications in alkaline media.  相似文献   

15.
An electrochemical approach to fabricate a nanostructured Fe/Pt-Fe catalyst through electrodeposition followed by galvanic replacement is presented. An Fe/Pt-Fe nanostructured electrode was prepared by deposition of Fe-Zn onto a Fe electrode surface, followed by replacement of the Zn by Pt at open-circuit potential in a Pt-containing alkaline solution. Scanning electron microscopy and energy-dispersive X-ray techniques reveal that the Fe/Pt-Fe electrode is porous and contains Pt. The electrocatalytic activity of the Fe/Pt-Fe electrode for oxidation of methanol was examined by cyclic voltammetry and chronoamperometry. The electrooxidation current on the Fe/Pt-Fe catalyst is much higher than that on flat Pt and smooth Fe catalysts. The onset potential and peak potential on the Fe/Pt-Fe catalyst are more negative than those on flat Pt and smooth Fe electrodes for methanol electrooxidation. All results show that this nanostructured Fe/Pt-Fe electrode is very attractive for integrated fuel cell applications in alkaline media.  相似文献   

16.
应用光阳极极化曲线, 电流-光强曲线、光谱响应曲线、平带电位以及电流相对增加与吸附时间之间的关系曲线研究了Ru~(3+)表面吸附对n-InP光电化学性能的影响, 还研究了其它一些阳离子吸附的影响。  相似文献   

17.
The influence has been investigated of the electrode filling of carbon paste electrodes on voltammetric measurements (peak current, peak potential, current voltage curve). Greater effects have been observed with the reduction of [Fe(CN)6]3? and with systems with adsorptive enrichment.  相似文献   

18.
Liteanu C  Haiduc I 《Talanta》1972,19(9):1009-1017
The behaviour of the bright palladium electrode toward the redox systems Cr(2)O(7)(2-)/Fe(2+) and Ce(4+)/Fe(2+) (in potentiometric titration) has been investigated as a function of pretreatment of the electrode. Anodization of the electrode at potentials higher than 800 mV increases DeltaE at the equivalence point by 300-400 mV for the dichromate titration. The sharp change in potential is due to the reaction between PdO(2) and Fe(2+). The equivalence point corresponds to the beginning of the potential drop, rather than the inflexion point, especially for dilute solutions. If the electrode is ignited before use the surface oxide PdO is oxidized to PdO(2) by Cr(V), the potential increases during the titration and DeltaE is 200 mV bigger than when an untreated electrode is used. In the titration of Ce(4+) with Fe(2+) the DeltaE is largest with untreated electrodes, and if the anodized electrode is used, the titration curves clearly show the reaction between PdO(2) and Fe(2+).  相似文献   

19.
The experimental conditions and parameters that control the transition from a steady to an nonsteady limiting current and vice versa in the anodic Fe dissolution are studied in sulfuric acid solutions by using a downward-facing Fe electrode. Periodic and chaotic current oscillations are observed at the beginning of the limiting current region within a fixed potential region by decreasing the sulfuric acid concentration, by increasing the Fe-disk rotation rate and by increasing a series external resistance. It is found that current oscillations emerge when theIR drop exceeds a critical value (IR)crit. The latter depends on the hydrodynamic conditions pertaining to the system. This is realized by the differences appeared in the value of (IR)crit on using a stationary or a rotating Fe electrode. The effect of hydrodynamic conditions is shown by additional experimental results obtained by using an upward-facing Fe electrode, by increasing the density and viscosity of the solution on addition of glycerol, and by altering the solution properties near the Fe surface on addition of halide ions. Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth. This article was submitted by the authors in English.  相似文献   

20.
The influence of electrolyte concentration on the potential dependent adsorption and desorption of octadecanol to/from a Au(111) electrode was investigated utilizing electrochemical and elastically scattered light techniques. The electrolyte concentration was found to influence the potential driven changes of the adsorbed layer (adsorption and desorption). The capacitive changes in the adsorbed layer were found to occur at more negative potentials with lower electrolyte concentration. The changes in the optical measurement, used to measure the characteristics of the desorbed species, or aggregates, were also found to be affected similarly. The magnitude of the overall change in the scattered light intensity was slightly dependent on electrolyte concentration. The re-adsorption of the aggregates was influenced by electrolyte concentration. The scattered light signal for an intermediate adsorbed state (adsorbed aggregate) was more prevalent for higher electrolyte concentration, suggesting that these intermediates were somewhat different compared to lower electrolyte concentrations. The lower electrolyte concentration displayed a larger potential region where this intermediate was stable, but the intensity of the scattered light was much lower. The electrolyte concentration most strongly influenced the potentials of adsorption and desorption, as well as the potential region of stability for the adsorbed intermediates. The sweep rate also has an influence on the scattering characteristics of the desorbed species, suggesting a possible method for measuring the kinetics of the adsorption–desorption process or for controlling the character of the desorbed species. These changes were explained in terms of a mechanism for the wetting or de-wetting of a surface. The influence of electrolyte concentration provides another opportunity for investigating the dynamics of this adsorption–desorption process.  相似文献   

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