Thanks George .... By second paragraph I mean, I check 2 different electrodes in FeCN6, the two electrodes are quite the same (the CVs overlap). I then put them in H2So4, there they are quite diffrent. I know the graphs should be different. I mean the current read for the two electrodes are way different. 

I would do the same George Lane said. Hard polishing, try to change the electrode, check reference and potential limits. Shifts may also be due to something that is electrodepositing over your electrode.

The oxidation and reduction peak of Au electrode depends on its surface roughness also. Try to maintain the same roughness and carry out the electrochemical cleaning also. Hope this will resolve the problem. 

The problem is the shift also occurs during the cleaning process (H2SO4 cycling) and thats why its wierd ... I should mention that my ref and aux are also gold .... But I didnt have the problem with the same design before but lately there are wierd shifts and .... I dont know what is going wrong

1. The current can never be the same for 2 different electrodes whatever they are from same material because of the roughness factor of the surface. So, the main point that you have to normalize your current ( change it to current density ), In that case you have to measure the real surface area first before each experiment, because the roughness factor of your electrode will be changed after each experiment and the cleaning process.

2. concerning the potential shift, what is the meaning for use also the aux and ref electrode from gold too, this looks so strange for me? and of course you should have a drift in potential as your reference will be drifted

Thanks for the comment .... Can you tell me more about how to change my current to current density and as for measuring the real surface area, I normally do that by calculating Q is that OK or shall I do something else.

I want to use my electrodes in a microfluidic system and so I cant use ext auxillary and reference. But considering the limitations in our institute, everything is made of gold

You are welcome at any time

for Gold, it is normally calculated the charge associated with oxide reduction for the voltammogram recorded in acidic or alkaline media.

then you have to divide this on the charge associated with oxide reduction corresponding to one centimeter square.

for more details, please see the reference below

after that you can divide the current you obtained on the real surface area you calculate and then you will get the scale in current density

Rand DA, Woods R (1971) J Electroanal Chem 31:29

Hi, 

As mentioned above this may be due to the problem with the reference electrode.

However, with gold electrodes you can see other problems:

For examples: 1- with FeCN6, it will adsorb on your electrode and the  shape of the CV may vary by time when you collect multiple scans. 

 2- With H2SO4 probably you are oxidizing/dissolving the electrode and so the surface area may change by time and this may cause a little shift in the potential.

This why your second scans are different from the first ones.

Good luck 

Speed of the electrolyte is also a key factor, particularly within that time limits it cannot follow up.Different different electrolyte have different mobilities  

Could you explain more about the speed ?

Also the enviroment conditions can be effect too besides high speed rates, I had the same problem. It is better to finish all of the experimental measurings in the same day if you are doing electrochemistry.

It means that the sample has voltage fading each time. So, the best one should have the lowest shift. The current actually should increase after cycling.