Activity evaluation of Pt/C catalyst for oxygen evaluation reaction in regenerativePEM fuel cell

Energy storage and conversion is a very important link between the stages of energyproduction and energy consumption. Fossil fuels are a traditional method of natural energystorage and an unsustainable method with limited reserves and pollution problems. Therefore,there is a need for a better choice to store and use green and renewable energy sources in thefuture, which is regenerative fuel cells (RPEMFC) due to the ability to hydrogen production inelectrolysis mode for energy storage and electricity generation in fuel cell mode can providehuman needs. Such a reversible system has several distinct advantages such as high specificenergy, low pollution, and most importantly, energy storage capacity (۱). In general, it can besaid that the mentioned system is a combination of a proton exchange membrane fuel cell(PEMFC) and a Proton exchange membrane water electrolyzer (PEMWE). Currently, carbonsubstrates are used as the catalyst substrate of fuel cells. In this work, the oxygen evolutionreaction (OER) activity of commercial Pt/C catalyst is evaluated using Linear sweepvoltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. Fig. ۱shows the LSV curves and Tafel slopes of the Pt/C Catalyst (۲۰ wt%) with potential cyclingbetween ۱.۲ and ۱.۸ V vs. RHE without and with ۱۶۰۰ rpm rotation rates. Onset potentials arethe parameters for evaluating the lowest potential required for starting the reactions. Whenevaluating the performance of an electrochemical catalyst, the onset potential is normally thefirst to be measured. However, it is difficult to obtain an exact value of the onset potentialsince the currents at this point are naturally very low. The Tafel analysis is usually employed tounderstand the reaction kinetics and mechanism, which is needed to compare the catalyticactivities of different catalysts. The onset potential and Tafel slope are listed in Table ۱, whichshows that the Tafel slope and the Onset potential change with the change of rotation. To elucidate the physical origins of the high catalytic performance in the Pt/C catalyst,electrochemical impedance spectroscopy (EIS) was used to examine the frequency-dependentresistances during the OER operating conditions. Fig۲ shows the Nyquist plot of the Pt/CCatalyst (۲۰ wt%) at ۱.۶ V vs. RHE with a ۵.۰ minute delay time, ۱۰۰ KHz to ۱۰ mHzFrequency Range, and ۱۰ mV AC amplitude, and Its fitting parameters are listed in Table ۲.According to the obtained results, the commercial Pt/C is an active catalyst for OER and can be ...

کلیدواژه ها:

Electrochemical impedance spectroscopy ، Nanocatalyst ، Oxygen evolution reaction ، Regenerative fuel cell.