The tafel curves of methanol electro - oxidation on tmchnodified pt / ti anode can be divided into three distinct regions 从tafel曲线来看,甲醇的电氧化过程分三个步骤。
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Transport in the diffusion layers and catalyst layers are described by a superposition of knudsen diffusion and stefan - maxwell diffusion , and electrochemical kinetics for anodic methanol oxidation and cathodic oxygen reduction are described by tafel equation 模型以stefan - maxwell扩散和knudsen扩散的叠加描述了气体混合物在多孔电极中的扩散过程,以tafel方程描述了甲醇在阳极氧化和氧在阴极还原的电化学动力学。
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Corrosion action slope cable used in cable - stayed bridge in different corrosion medium such as synthesis sea water , solution nacl and simulation acid rain are studied by electrochemical method , for example , linear polarization , tafel extrapolation and ac impedance method 对此,本论文以人造海水、 nacl溶液、模拟酸雨作为腐蚀介质,针对不同类型的钢绞线,采用线性极化法、 tafel外推法和交流阻抗法等电化学方法研究斜拉桥拉索结构中钢绞线在不同介质中的腐蚀行为。
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The corrosion potential was the biggest and the corrosion current was the smallest one when the concentration of super - 3900 was 0 . 5 % ; the corrosion potential was increased with the addition of mps - dl , but the smallest corrosion current is under 0 . 01 % mps - dl . the rust time was the longest one when the concentration of super - 3900 was 0 . 5 % as well as mps - dl was 0 . 01 % . it was increased as a peak curve with al2o3 concentration in plating solution and ph value increased gradually with cathodic current density ; the corrosion weight 通过测量tafel曲线可知,在super - 3900浓度为0 . 5 % (相对于镀液的体积百分含量)时获得的镀层腐蚀电位最正,腐蚀电流密度最小;随着镀液中mps - dl含量的增加,获得的镀层的腐蚀电位逐渐正移,在浓度为0 . 01 % (相对于镀液的体积百分含量)时腐蚀电流密度最小。
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6 ) , the process that h20 is adsorbed on the electrode surface and the hydroxyl group is formed to oxidize the co may be the rate - determining step ; in the region iil ( logi > l . 6 ) , all of the tafel curves show a curvature until the current densities reach the peak value , indicative of a possible limiting current . the effect of rare earth elements on methanol electro - oxidation has not been reported in literatures 在低极化区( logi 1 . 3 ) ,甲醇发生脱氢反应并形成反应中间体,其中co成为未被氧化的毒物,此过程成为速率限制步骤;在更高的极化区( 1 . 3 logi 1 . 6 ) , h _ 2o吸附在电极表面并解离生成[ oh ] ,促进了co的氧化,此为此阶段速率控制步骤:在第3个极化区( 10gi 1 . 6 ) , tafel曲线发生弯曲,电流密度也最终达到峰值。
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In acid copper sulphate solution , the nc copper has a more negative corrosion potential which is decreasing with reducing the grain size and diffusion impedance was only found in the as - prepared and as - annealed at 180 ? nc copper due to the diffusion within the pores and channels on the surface . both the tafel plots and eis study demonstrated that the nc copper exhibits a higher corrosion current and lower polarization resistance than its mc couterpart 在酸性硫酸铜溶液中,纳米晶铜的腐蚀电位比微米晶铜要负,并且随着晶粒尺寸的减小而降低。 eis研究表明,未退火的和180退火的纳米样品中发现了扩散阻抗,与表面孔洞和通道中的扩散有关。极化曲线外推法和电化学阻抗研究都表明纳米晶铜的腐蚀电流比微米晶铜高,而极化电阻要低。
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In the first part of this paper , mn ( iii ) / mn ( ii ) couple in h2so4 was firstly applied as the positive couple to this system , i . e . redox flow cell . its chemical , electrochemical properties , redox kinetics and related parameters were characterized and discussed by rotating disc electrode ( rde ) , cyclic voltammetry ( cv ) , a . c . impedance ( a . c . imp ) , chronoamperometry , tafel curve , and galvanostatic charge / discharge techniques . conclusions have been drawn as follows : 1 . the electrochemical kinetics of mn ( iii ) / mn ( ii ) redox couple in 6 . 3m h2so4 solution were studied by means of rotating disc electrode ( rde ) technique on platinum electrode 本文第一部分首次成功地将酸性介质中的mn ( iii ) / mn ( ii )电对应用于氧化还原液流电池这一新型储能装置的正极活性材料,通过旋转圆盘( rde ) 、循环伏安( cv ) 、交流阻抗( a . c . imp ) 、恒电位阶跃、 tafel实验以及mn ( iii ) / mn ( ii )单电极的恒流充放电实验,我们得出以下结论: 1 .在旋转圆盘电极上,不同转速范围,不同的极化过电位, mn ( ) / mn ( )体系氧化还原电极过程的控制步骤不同,电荷传递、扩散传质可分别或联合成为控制步骤。