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

Voltammetry is one of the electrochemical methods used to test the electrode processes of fuelcells, 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 andperformance of fuel cell catalyst layer can be obtained. These information include electrontransfer 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 processeswhich influence on the reduction of oxidant and stability of platinum in the cathode of polymerexchange membrane fuel cell (PEMFC). These two processes are responsible for coveragepercentage of catalyst area by oxidized materials (PtOn), which prevents the operation of oxygenreduction reaction (ORR) and therefore the activity of catalyst decreases [2].In this study, the typical model of cyclic voltammogram and linear sweep voltammogram for thecathode of PEMFC are investigated. For these purpose, the mechanism and kinetic of solvationand oxidation of platinum and the effect of structural parameters were assayed. In order tomathematical modelling, the Butler–Volmer equation and a series of electrochemicalfundamental equations with considering desirable boundary conditions were used. Furthermore,the effect of environmental parameters such as temperature, humidity, size of nanoparticles andamount of catalyst loading on outcoming current caused by scan of potential between 0 – 1.2volts with different scan rates were investigated and the results were compared with theexperimental data. The obtained results showed that relative humidity increased the rate ofsurface oxidation and therefore decreases the activity of catalyst. However, increment of temperature of cell and nanoparticles size of catalyst lead to increase the catalyst activity asobserved by experiments [3, 4].

Keywords:

Mathematical Modelling , Cyclic Voltammogram , Linear Sweep Voltammogram , Platinum Catalyst , PEMFC