Mathematical Modelling of Cyclic Voltammogram and Linear Sweep Voltammogram for Cathode of Polymeric Fuel Cell

Voltammetry is one of the electrochemical methods used to test the electrode processes of fuel cells, generally in two forms of cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Based on the results of especially two mentioned methods, many information about structure and performance of fuel cell catalyst layer can be obtained. These information include electron transfer kinetic, electrochemical active surface area, activity and stability of catalyst layer [1]. Solvation and oxidation of platinum as the most practical catalyst metal are important processes which influence on the reduction of oxidant and stability of platinum in the cathode of polymer exchange membrane fuel cell (PEMFC). These two processes are responsible for coverage percentage of catalyst area by oxidized materials (PtOn), which prevents the operation of oxygen reduction reaction (ORR) and therefore the activity of catalyst decreases [2]. In this study, the typical model of cyclic voltammogram and linear sweep voltammogram for the cathode of PEMFC are investigated. For these purpose, the mechanism and kinetic of solvation and oxidation of platinum and the effect of structural parameters were assayed. In order to mathematical modelling, the Butler–Volmer equation and a series of electrochemical fundamental equations with considering desirable boundary conditions were used. Furthermore, the effect of environmental parameters such as temperature, humidity, size of nanoparticles and amount of catalyst loading on outcoming current caused by scan of potential between 0 – 1.2 volts with different scan rates were investigated and the results were compared with the experimental data. The obtained results showed that relative humidity increased the rate of surface oxidation and therefore decreases the activity of catalyst. However, increment of 383 temperature of cell and nanoparticles size of catalyst lead to increase the catalyst activity as observed by experiments [3, 4].