Dear Layla Haythoor Kharboot , Details for WE preparation can be found in the material and methods part of any article relevant to your electrochemical study. Most commonly, the desired amount of catalyst (2-10mg) is dissolved in a solvent mixture of (Isopropanol/ethanol+water+nafion- 0.8+0.15+0.05). Here is the WE preparation protocol from the attached reference.
For the working electrode preparation, 2 mg sample was added into 200 µL mixture containing 10 µL Nafion (5%) 50 µL isopropanol and 140 µL ethanol followed by ultrasonication for 30 minutes to form a uniformly dispersed ink..