Experimental Study as Well as DFT Calculations for Ion Transport in Hydrogen/Platinum/Iridium Electrode of Fuel Cells through h-BN Layers in Proton Exchange Membrane
摘要
In the fuel cell of a solid acid electrolyte, H+ conducting oxyanion salt (solid acid) consists of a solid supported within the membrane which is saturated with H2O for any further ions transporting. In this study, Platinum-Iridium binary electrodes were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical techniques, and CO stripping. By this work we simulated our system to reduce the poisoning effect of mono oxide carbon (CO) problem, and an acceptable progress has already been made in improving the anode CO tolerance. We used Platinum-Iridium alloys to reduce the poisoning effect, which exhibited an alloy with Pt(30%)/Ir(70%) to be more tolerant to CO than pure Pt. By DFT method, we calculated the energetics of CO adsorbed on the system to be such that CO tends to diffuse from catalytically active Platinum onto the Iridium substrate. This mechanism requires Platinum-Iridium islands to be small. Meanwhile further DFT calculations exhibited the propensity of Platinum-Iridium atoms to coalesce and form with iridium. For any further confirmation of the results the cyclic voltammograms of a Platinum(111) electrode before and after deposition of various amounts of Platinum-Iridium alloys were also tested and finally hydrogen and water diffusion through h-BN located in two electrodes were discussed. As a result, it was confirmed that Iridium loading up to 70% was caused in electrochemically active surface (EAS) area and better electro-catalytic performance toward methanol electro-oxidation reaction.