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[交流] 关于ECAS的求法请大牛解惑

本人电催化刚入门的一个新虫近日看到两篇文章ECAS的算法有些不明白，求大神指导
1、Calculation of ECAS: The calculation of electrochemically active surface area (ECAS) is estimated from the double layer capacitance (Cdl) of the different catalysts in 1 M KOH based on the previous published report.1-3 The charging current (ic) was measured from the CVs at different scan rates, as shown in Figure S4c and Figure S13. The relation between ic, the scan rate (ν) and the Cdl was given in equation (1). ic = νCdl，Therefore, the slope of ic as a function of ν is equal to Cdl. For the calculation of ECAS, the specific capacitance (Cs) value is 0.040 mF cm-2 in 1 M KOH. So the ECAS of is calculated according to equation (2). ECSA=Cdl/Cs。文章题目：A General Approach to Ultrathin NiM (M = Fe, Co, Mn) Hydroxide Nanosheets as High-Performance Low-Cost Electrocatalysts for Overall Water Splitting
这个是说用Cdl/Cs，但是Cs直接给出了，这个是需要测的吗？如果需要测那么测试的电流密度是多大的？
2、Estimation of Effective Electrode Surface Area. Based on literature, cyclic voltammetry (CV) could be carried out in neutral media to probe the electrochemical double layer capacitance of various samples at non-Faradaic overpotentials as the means for estimating the effective electrode surface areas. Accordingly, a series of CV measurements were performed at various scan rates (4 mV s-1, 8 mV•S-1, 12 mV•S-1, 16 mV•S-1, etc.) in 0.104 to 0.204 V vs. RHE range, and the sweep segments of the measurements were set to 10 to ensure consistency. By plotting the difference in current density (J) between the anodic and cathodic sweeps (Janodic - Jcathodic) at 0.15 V vs. RHE against the scan rate, a linear trend was observed. The slope of the fitting line is found to be equal-to-twice the geometric double layer capacitance (Cdl), which is proportional to the effective electrode surface area of the materials. Therefore, the electrochemical surface areas of different samples can be compared with one another based on their Cdl values. However, it should be noted that this comparison makes sense only when the measurement of materials are carried out under same condition.
这个是那另外一个材料进行比较，把二者之间的Cdl都给求出来，我们的材料是直接长在泡沫镍上片的如果要对比的话需要选用什么样的材料，其实对整个过程还是有些糊涂求大神详解。
3、是没有在文献查找是在网上的查到的，是利用可根据Randles-Sevcik公式在25°C时，ip=(2.69×105)n3/2ADo1/2ν1/2C （没法下标这个公式有点乱那个是10的五次方不是105）。0.05mM K3Fe（CN）6 （0.1M KCl）其扩散系数 Do=7.6*10-6。在此溶液中根据不同扫速做ip与V1/2的关系来求A。这个方法适合什么样的样品？我们现在做的是过渡金属化合物直接长在泡沫镍上，不知道能不能用。
希望各位大牛能够提供帮助

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1楼2017-11-06 15:09:57

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我也在想这个问题，第一个我也不清楚为啥求得了Cs的值我看的这个文献给了个参考文献：Anothumakkool, B.; Torris A. T, A.; Bhange, S. N.; Badiger, M. V.; Kurungot, S.Electrodeposited Polyethylenedioxythiophene with Infiltrated Gel Electrolyte Iinterface: A Close Contest of an All-Solid-State Supercapacitor with its Liquid-State Counterpart. Nanoscale 2014,6, 5944–5952.
希望对你有帮助。第二个意思是说在同一条件下测得Cdl值由于线性关系和ECAS一样的。能看到谁最好就可以了。
第三个你说的那个公式没看明白。