Is there an empirical or theoretical standard value for this (at room temperature) and for different electrolyte concentrations? Is there a resource available that provides a chart of values for common electrode materials in common electrolytes?
Thanks, I have found values over a range of 20 to 100 µF/cm2 stated in the literature. I have been getting about 70 µF/cm2 fairly consistently by using either electrochemical impedance spectroscopy (and fitting to a simple series RC model) or by measuring the height of the rectangular CV curve sweeping from -100mV to +100mV re Ag/AgCl.
It depends on surface morphology and how smooth is your electrode, but also on potential. It has been studied in the last century, look for the works of the group of D.Kolb,One place to start:
T.Pajkossy, Th.Wandlowski, D.Kolb, Impedance aspects of anion adsorption on gold single crystal electrodes, J.Electroanal.Chem., 1996, 414(2), 209-220
Generally, you are right, surface specific capacitance of Au/H2SO4 interface is in the range 35-70 uF/cm2 (integral capacitance). But, as I said, it depends on surface conditions.
The best way to find it is to measure it your self. Measure integral capacitance (by intergrating CV curve), and divide it by surface area. The latter for Au you can easily and precisely measure by Cu-upd, for example. And if you want differential capacitance, divide current density by sweep rate.
The more detailed analysis involves impedance measurements, of course. But this is more complicated. Depends on your needs.
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