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[求助]
关于HER的tafel测量问题 已有1人参与
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本人电化学小白，最近在析氢测试，对于tafel斜率会进行拟合，但是对lsv的正负扫向问题很疑惑。 我知道析氢测试的lsv极化曲线是进行负扫，但看到有说tafel的拟合需要通过lsv正扫计算，通过测试这两者的拟合结果存在出入 负扫的tafel会更小一些。 那究竟正扫负扫哪个是正确的，为什么会存在出入呢，如果可以请帮我找到参考文献，谢谢大家了！ @Gamry-电化学 @langzhizhou @louderbe 发自小木虫Android客户端 |
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2楼2018-03-21 15:24:50
3楼2018-03-27 01:14:08
Gamry-电化学 
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【答案】应助回帖
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首先， 对电位的正负规定，欧洲和美国的科学家，尤其在电催化领域，有些不同，看下面的介绍： https://en.wikipedia.org/wiki/El ... al#Sign_conventions Sign conventions Historically, two conventions for sign for the electrode potential have formed:[2] convention "Nernst–Lewis–Latimer" (sometimes referred to as "American"  ,convention "Gibbs–Ostwald–Stockholm" (sometimes referred to as "European" .In 1953 in Stockholm[3] IUPAC recognized that either of the conventions is permissible; however, it unanimously recommended that only the magnitude expressed according to the convention (2) be called "the electrode potential". To avoid possible ambiguities, the electrode potential thus defined can also be referred to as Gibbs–Stockholm electrode potential. In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of E for a half-cell reaction when it is written as a reduction. The main difference between the two conventions[4] is that upon reversing the direction of a half-cell reaction as written, according to convention (1) the sign of E also switches, whereas in convention (2) it does not. The logic behind switching the sign of E is to maintain the correct sign relationship with the Gibbs free energy change, given by ΔG = -nFE where n is the number of electrons involved and F is the Faraday constant. It is assumed that the half-reaction is balanced by the appropriate SHE half-reaction. Since ΔG switches sign when a reaction is written in reverse, so to, proponents of convention (1) argue, should the sign of E. Proponents of convention (2) argue that it is more convenient to consider oxidants and reductants on the same scale. （2） 把BARD的JACS一篇文章， 放上，看其中的一种说法：析氢测试的lsv极化曲线是进行负扫: First, the MoS2 substrate potential was swept from 0 V to − 0.7 V at a scan rate of 5 mV/s to generate hydrogen continuously, and the hydrogen was then collected at the Pt UME tip. https://pdfs.semanticscholar.org ... 7029b2749dc3581.pdf 欢迎其他专家给出见解。 |
4楼2018-03-27 03:21:11
