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[求助] 请问在做电容器的时候,测CV的时候氧化还原的峰在逐渐增大,因...

请问在做电容器的时候,测CV的时候氧化还原的峰在逐渐增大,因此物质的电容也在增大。同样的,在测GCD的时候,为啥电容会减小 @Gamry-电化学

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Gamry-电化学

金虫 (职业作家)


好的问题。CV中峰对应的电容和GCD对应的电容,某些情况对应不一样。请看下面链接了解更多牛人讨论。https://www.google.com/amp/s/www ... lic_voltammetry/amp

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2楼2017-09-03 21:04:36
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Gamry-电化学

金虫 (职业作家)


引用和Copy:
George Zheng Chen
109.41 ·
University of Nottingham (UK and China Campues)
Capacitance value can be determined from CV and GCD. For this purpose, the CV must be rectangular, and the GCD be linear (or triangular). Peak-shaped CV and non-linear GCD should not be used for capacitance analysis.

The differential capacitance as mentioned above is useful for capacitance analysis in the context of supercapacitor only if the CV is rectangular.

For using a rectangular CV and linear GCD, the simple equation below is used.

C = Q/U

where C is the capacitance, Q the charge passed for recording the CV or GCD. Note that in both cases, you can use either the Q value from forward or backward scan; or charging or discharging. However you can also use the total Q value derived from the area enclosed in the CV, and of course the total Q needs to be divided by 2.

I shall point out that the CVs attached to your message are peak-shaped and hence not suitable for capacitance analysis. However, you may obtain a rectangular CV if you record your CV in a narrower potential range, e.g. between -0.1 V and -0.6 V. If so, you can use the above simple equation.

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3楼2017-09-03 21:06:59
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新虫 (小有名气)

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3楼: Originally posted by Gamry-电化学 at 2017-09-03 21:06:59
引用和Copy:
George Zheng Chen
109.41 ·
University of Nottingham (UK and China Campues)
Capacitance value can be determined from CV and GCD. For this purpose, the CV must be rectangular, and the GCD ...

首先,谢谢回复,但是没太懂。我的东西吧,刚准备做测试,然后一开始测GCD,恒流充放电100次后,电容大小不变,然后我就继续测CV100次,CV给出的氧化还原峰一直在增加,然后我就又继续测GCD,此时,电容就增大了许多,这是为什么呢?

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4楼2017-09-03 23:30:55
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Gamry-电化学

金虫 (职业作家)


主要由于CV测试,引起活性材料表面发生变化。问一下,CV的电位区间和GCD的分别是什么范围。

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5楼2017-09-06 23:43:52
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