Estimation of Active Surface Area of Platinum by Electrochemical Impedance Spectroscopy

Abstract

Platinum is used as an electro-catalyst for the oxidation of hydrogen and reduction of oxygen in fuel cell. High surface area of platinum is achieved by using 2-5nm particle size. However, this also leads to loss of active surface area with the operation of fuel cell. In this study, active surface area of Pt in 0.5M H2SO4 solution was estimated from capacitance value measured by electrochemical impedance spectroscopy (EIS) and under potential deposited hydrogen (UPD-H) from CV and compared. The results showed that both the techniques gave similar trend in the variation of active surface area with the CV cycle. The active surface area estimated from capacitance value was slightly higher than that estimated from UPD-H value.