Study Of Oxygen Permeation Performance Of Pt-doped Composite Proton Exchange Membrane

The key to the development of proton exchange membrane fuel cells is to increase the lifespan,and one of the main factors affecting the lifespan is the attenuation of the proton exchange membrane.Therefore,to further improve the lifespan of fuel cells,it is necessary to develop long-life proton exchange membrane materials.Many studies have shown that the oxygen permeating from the cathode to the anode will directly react with hydrogen under the action of the anode catalyst.At the same time,because the anode potential is close to zero,the reaction is more inclined to two-electron reaction to generate free radicals,and the attenuation caused by the generation of free radicals.It is one of the main restricting factors of the lifetime decay of the proton exchange membrane.At present,the research on improving the oxygen permeation of fuel cells by proton exchange membranes has received more and more attention.Among them,Gore has developed a Pt-doped proton exchange membrane to hinder oxygen permeation.However,the role of Gore’s Pt-doped proton exchange membrane in hindering oxygen permeation is still unclear,so we used Gore’s Pt-doped proton exchange membrane to study the situation of oxygen permeation in fuel cell operation.And use magnetron sputtering Pt technology to prepare Pt on porous PTFE to prepare Pt-doped composite proton exchange membrane,and discuss the mechanism of Pt nanoparticles hindering oxygen permeation in the proton exchange membrane during battery operation,which is an anti-oxygen permeation membrane.The development of electrode materials provides a theoretical basis.The study found:1.An embedded microelectrode oxygen permeation in-situ online test method was used to evaluate the oxygen permeation of Gore’s black membrane.It was found that Gore’s Pt-doped composite proton exchange membrane does impede oxygen permeation from the cathode to the anode.The test results showed that the anode/cathode pressure difference was the main influence on the oxygen permeation of the proton exchange membrane,and the higher the anode pressure,the lower the oxygen permeation of the proton exchange membrane.The oxygen permeation behavior of the undoped Pt composite proton exchange membrane exists and decreases gradually with the increase of anode/cathode pressure difference,and disappears when the pressure difference is greater than 60 k Pa.In contrast,the Pt-doped composite proton exchange membrane has good oxygen consumption ability due to the presence of Pt nanoparticles,and no oxygen permeation occurs at the anode/cathode pressure difference from-100 k Pa to 100 k Pa.At the same time,it also shows that the Pt-doped composite proton exchange membrane of Gore M775.15 is overloaded with Pt and has room for further reduction.2.The composite proton exchange membrane was prepared by magnetron sputtering in porous PTFE loaded Pt nanoparticles followed by negative pressure vacuum impregnation with PTFE as the base material filled with perfluorosulfonic acid resin and then protonated,and the Pt particle size was found to be about the same(about 3 nm)and more uniformly dispersed compared with the Pt-doped composite proton exchange membrane from Gore by magnetron sputtering.The Pt-loaded composite proton exchange films prepared by magnetron sputtering can also control the Pt particle size by argon pressure and power supply,and the amount of Pt loading(0-30μg/cm~2)can be controlled by extending the sputtering time.The Pt-doped composite proton exchange membrane with magnetron sputtered Pt loading was tested by in situ oxygen permeation test method with embedded microelectrodes,and it was found that the Pt-doped composite proton exchange membrane with Pt loading of 3.404μg/cm~2and 2.125μg/cm~2could hinder oxygen permeation,which was consistent with the oxygen permeation phenomenon of Gore’s Pt-doped composite proton exchange membrane(Pt loading of 23.45μg/cm~2).The results are consistent with the oxygen permeation phenomenon of Gore’s Pt-doped composite proton exchange membrane(Pt loading 23.45μg/cm~2).Therefore,the experimental results show that the Pt loading of 23.45μg/cm~2in Gore’s M775.15 Pt-doped composite proton exchange membrane is much higher than the actual required Pt loading,which causes the waste of Pt and increases the cost of the proton exchange membrane.The effect of oxygen permeation can be achieved with the lowest Pt load.