The potential of the RHE depends on the pH of the electrolyte solution. In 0.5 M H2SO4 the pH is close to 0. Therefore the potential of the RHE can be calculated to E0=0.0 - 0.059 * pH; in this case the potential of the RHE is therefore also 0.0V.

The potential of the Ag/AgCl electrode depends on the concentration of the solution used in the electrode itself. If you have a sat. solution then the potential is +0.197V. To convert now your CV data recorded with the Ag/AgCl electrode you have to shift the recorded potential according to this equation: E(RHE)=E(Ag/AgCl) + 0.197V. So you must simply add to your existing potential the shift of the Ag/AgCl electrode. If you have a Ag/AgCl electrode with 3.5M then add +0.205V or +0.210V for a electrode with 3.0M.

http://www.consultrsr.net/resources/ref/refpotls3.htm

 This link will be helpful in the interconversion of any reference electrode potential to the desired one. 

E vs. RHE = E Ag/AgCl + 0.06*pH +  Eo Ag/AgCl 

Here,  E Ag/AgCl = Potential that you got  Eo Ag/AgCl = 0.199 

In general,

For conversion of  potential collected with reference to any electrode in RHE following formula is used

E vs.RHE = E ref + E 0 ref + 0.06 * pH

Dear All

this link is suitable "for conversion"

http://www.consultrsr.net/resources/ref/refpotls3.htm

E/V vs RHE = E/V vs Ag/AgCl + 198 mV + (pH x 0.05916)

The formula is 

E(RHE) = E (Ref) + E0 (Ref) + 0.059pH

In 0.5 M H2SO4 solution, pH = 0, then

E(RHE) = E (Ref) + E0 (Ref) 

Experimentally also you can get the value by calibrating the reference electrode. Basically you should do calibration instead of directly using the equation.

The procedure is,

Use 3-electrode system using your reference electrode as the reference electrode, two Pt electrodes as working and counter electrode in the electrolyte (whatever you are using, in your case it is 0.5 M H2SO4 solution). Saturate the electrolyte with hydrogen gas by long time purging. Now you run a CV in the hydrogen evolution range (for the present case suppose from 0 to -0.5 V) with constant purging of hydrogen gas. 

Now in your CV, you have to see that potential where your CV crosses 0 current in both forward and backward sweeping. Take that / those potentials, take the average. This will be your calibration value. If your reference electrode is absolutely fine, then your calibration value (E (cali) will be very close to E0 (ref).

So,

E (RHE) = E (ref) + E (Cali)

For further understanding please go through the supporting information of the following paper

http://pubs.acs.org/doi/abs/10.1021/acsenergylett.6b00184

Dear Muhbuba, here is my short answer for your question:

you can use the following link to convert what you want

http://www.consultrsr.net/resources/ref/refpotls3.htm

To summarize, the potential of the Ag/AgCl electrode depends on the concentration of the solution used in the electrode itself. If you have a sat. solution then the potential is +0.197V. To convert now your CV data recorded with the Ag/AgCl electrode you have to shift the recorded potential according to this equation: E(RHE)=E(Ag/AgCl) + 0.197V. So you must simply add to your existing potential the shift of the Ag/AgCl electrode. If you have a Ag/AgCl electrode with 3.5M then add +0.205V or +0.210V for a electrode with 3.0M.

Hi everyone, I am working on characterizing the E1/2 of different catalysts. But I am confused about the reference electrode. Why most researchers convert their potential data with respect to RHE no mater what actual reference electrode they used? Since RHE is dependent on the pH value of the electrolyte, it is not possible to compare the E1/2 values obtained in different electrolytes. Why not convert all the potential data with respect to SHE? More specifically, I am working on the oxygen reduction catalysts. Some researchers test the ORR property in 0.5 M sulfuric acid (pH=0.3) someone prefer 0.1 M perchloric acid (pH=1). When they convert the E1/2 with respect to RHE. The experiment done in the perchloric acid would benefit ~40mV from the electrolyte for the same catalyst. Therefore, I am wondering why the reference point is not set to SHE for the direct comparison of different catalysts?

This is another link which you can convert and report your potential versus different standard electrode;

https://www.gamry.com/support/electrochemical-calculators-tools/convert-potentials-to-another-reference-electrode/

You can calculate the theoretical value by the equation mentioned above :

* E(RHE) = EAg/AgCl + 0.059 pH + Eo Ag/AgCl

*Where Eo Ag/AgCl = 0.1976 V at 25°C and  E Ag/AgCl is your working potential.

but, from point of view experimental: this value could be less than the theoretical one. So, you should verify your potential difference before experiment to be sure for your measurement. for this reason, i recommend Debdyuti Mukherjee measurement to determine the potential difference experimentally

what is the electrode potential of carbon electrode?

i think this link will be useful to u

http://www.consultrsr.net/resources/ref/refpotls3.htm

what about when the temperature is at 50 degrees?

The answer provided by Mohamed Benchakar is for 25 degrees Celsius. A more general form of the pH dependent component of the equation is: ln(10)*(RT/F)*pH, where R, T, and F are the universal gas constant, temperature in Kelvin, and Faraday's constant, respectively. Simply substitute the temperature you need into this equation (298.15 K yields the 0.059*pH correction referenced in Mohamed's answer).

Thank you very much

I'm confused.

is it now RHE = E0 + 60 mV *pH + E or RHE = E -- 60 mV*pH + E0 ??

Are there references for the derivation from the Nernst equation?

Help would be much appreciated.

If you work with reference electrodes, and do not have an extensive working knowledge of basic chemistry (as few people nowadays seem to have), I would recommend to take your time and read the standard book of Ives and Janz from the 60s. You should not be in a hurry, and you should get to know the basic principles involved in reference electrodes.

There are so many errors that you can make. For instance, sulfur compounds can wreak havoc. Especially in a biological environment, many things can go wrong: because of the low solubility of oxygen in water, a medium can easily turn anaerobic. If your medium smells, be careful!

It is always a good idea to prepare a set of reference electrodes, and compare their mutual voltage.

If your electronic system is moderately complex, look with a scope every now and then for hum.

The smaller the reference electrode, the higher the input voltage of the voltage meter should be.

It is a good idea to browse through some old textbooks, for instance on analytical chemistry, once in a while.