Performance Optimization Of Membrane Electrode In Pemwe And Research On Non-precious Metal Catalyst

The consumption of fossil energy and the continuous deterioration of the ecological environment have led to vigorous development and use of renewable clean energy to solve the current energy crisis as a top priority.However,renewable energy has its own inhomogeneity and intermittent characteristics,which leads to its low utilization rate and relatively low proportion.Because hydrogen has the advantages of cleanliness,zero carbon emissions,and high energy density,converting and storing renewable energy into hydrogen energy has become a solution.At the same time,water electrolysis hydrogen production technology has gradually moved towards commercialization,especially the hydrogen production system based on proton exchange membrane(PEM)water electrolysis cell has a fast response speed,adapts to the characteristics of dynamic operation,and is suitable for hydrogen production by renewable energy.The hydrogen used as an energy carrier for industrial production or as a fuel for use in fuel cells is the development idea of hydrogen storage and energy recycling in recent years.However,PEM water electrolyzers still have problems such as insufficient catalyst utilization and high cost caused by the use of precious metals,which limit their large-scale commercial application in a short time.Therefore,on the one hand,improving the utilization rate of precious metal catalysts by optimizing certain aspects of the membrane electrode preparation process,on the other hand,developing high-activity non-noble metal catalysts to replace the currently used precious metal catalysts has become an urgent problem to be solved.In response to the above problems,this thesis mainly completed the following tasks:(1)By optimizing the Nafion content and IrO2 catalyst loading of the MEA of the PEMWE when using commercial IrO2 catalyst to prepare the catalyst layer,the performance of the MEA for water electrolysis can be greatly improved,the overpotential required for the reaction can be effectively reduced,and output current density of the MEA under the working voltage can be improved(current density of 2.32 A/cm2 can be generated under a voltage of 2.5 V).(2)By loading the commercial IrO2 catalyst on Vulcan carbon black and optimizing the loading amount,its surface area can be effectively increased,and its utilization rate can be improved in a wide range.Meanwhile,the prepared catalyst layer is more capable of utilizing the mass transfer of reactants and products.By optimizing the Nafion content and loading capacity after loading,the water electrolysis performance of the MEA is further improved(current density of 4.21 A/cm2 can be generated at a voltage of 2.5 V).(3)Using the non-precious metal cobalt nickel nitrate as the precursor,a highly active HER catalyst was prepared through a simple synthesis method and controlling the phosphating temperature,the amount of sodium hypophosphite,and the hydrophilicity and hydrophobicity of the carrier during the synthesis process.The test on the rotating disk electrode shows that the overpotential is only 43 mV at a current density of 10 mA/cm2,and the overpotential only increases by 17 mV after a 10 h stability test;it was carried out at 500 mA/cm2 for 14 h In the stability test,its overpotential hardly increased,indicating that it has high stability.(4)The prepared high-activity HER catalyst was prepared as a MEA and assembled on a PEMWE for water electrolysis performance test,and factors such as Nafion content and catalyst loading during the preparation process of the MEA were adjusted.The test results show that the current density of 2.21 A/cm2 can be generated at 2.5 V when 30℃,and the high current density of 2.77 A/cm2 can be generated at 2.5 V when 60℃,showing a good application in PEMWE prospect.The main goal of this thesis is to reduce the cost of cathode catalyst of the MEA in PEMWE.On the basis of optimizing the performance of anode catalyst layer of the MEA,a non-precious metal phosphide HER catalyst is constructed for MEA of PEMWE for water electrolysis.The final test results show that the use of non-precious metals to replace precious metals for electrolyzed water has a wide range of applications.