Study On The Electrocatalysts And The Cathode Structure Of Proton Exchange Membranes Fuel Cells

Electrocatalyst is one of key materials of proton exchange membrane fuelcells (PEMFCs). At present, the cost of the electrocatalysts used in PEMFCs isvery high, which is one of the obstacles for the commercialization of PEMFCs.Membrane electrode assembly (MEA) is the core of PEMFC, and it is the placefor the electrochemical reaction. But the three-phase reaction zones are notextended effectively and the utilization of catalysts is very low in MEAs preparedby the present processes. Therefore, the aims of this thesis are to develop low Ptloading catalyst with high activity, to optimize the cathode structure and toexplore new method for preparing catalyst layer.The cathode structure of PEMFCs was studied in this thesis. At first, theconditions and parameters for preparation of MEAs and operation of fuel cellswere optimized. And then a novel method for preparing catalyst layer wasdeveloped by pyrolyzing Nafion partly. In this Nafion-prolyzed electrode, Nafionis a bonder and a proton conductor and partly prolyzed Nafion without sulfonicacid group is a hydrophobic material.Incipient wetness method was successfully used to prepare electrocatalystsfor PEMFCs. Pt-M/C (M=Fe, Co) catalysts for oxygen reduction in cathode andPtRu/C catalysts for CO tolerance in anode were prepared by incipient wetnessmethod, respectively, and they were characterized by XRD, TEM, RDE, TG-MSand single cell test.In this thesis, Au was firstly used to prepare electrocatalyst for CO tolerancein PEMFCs as an active component. A new kind of CO tolerant catalysts,PtAu-Fe2O3/C catalysts, was developed using incipient wetness method. Theeffect of Au content in catalyst and the heat-treatment temperature were studied.A good performance for CO tolerance was acquired using this kind of catalyst asanode catalyst in single PEM fuel cell.