Preparation And Study Of Proton Exchange Membranes And High Efficiency Electrocatalysts For Fuel Cells

Proton exchange membrane fuel cell?PEMFC?is a device that can convert chemical energy of fuels into electricity directly.It is considered to be one of the cleanest and most efficient power generation technologies in the 21st century because of its high energy efficiency,good stability and environmental benefits.However,PEMFCs are not produced in large quantity and applied commercially until now.One of the obstacles is the low conductivity of PEM in the high temperature and low humidity.The others are the high cost of catalysts,low performance and poor stability.?1?In this work,the electrocatalysts Pt/WC_x/C were prepared by in-situ carbonization.The composition and microstructure of Pt/WC_x/C were characterized by XRD,SEM,TEM and EDS.The results show that the particle size of Pt and WC increases from 5 nm to 25 nm with the increase of WC content.The catalytic performances of Pt/WC_x/C were tested in acid solution.The results indicate that,in the CV curves of electrooxidation methanol,the peak current density of Pt/WC_20%/C and ETEK are 556.20 mA mg^-1_Ptt and 405.6 mA mg^-1_Ptt respectively.The peak current density of Pt/WC_20%/C is about 150 mA mg_Pt^-1bigger than the ETEK.In the CV curves of CO dissolution,the peak potential of Pt/WC_25%/C and ETEK are 0.55 V and0.66 V respectively.The peak potential of Pt/WC_20%/C is lower than the ETEK,which means the introduction of WC enables the catalyst to oxidize CO at a lower potential.?2?Pd_xCo_y/rGO composite catalysts with different Pd:Co ratios were prepared by electrodeposition.The composition and structure of catalysts were characterized by SEM,TEM,EDS and FTIR.The results show that the molar ratios of the composite catalysts are corresponding to the stoichiometric ratios.When Pd:Co ratio is 1:3,the metal has smallest diameter and uniform distribution.The electrochemical performances of the catalysts were tested in acidic electrolytes.The results indicate that Pd₁Co₃/rGO catalyst demonstrates the biggest ECSA and best stability for formic acid electrooxidation and strongest anti-CO poisoning ability in acid environment.?3?In this work,a novel nanocomposite material,HMSN impregnated with HPW,briefed as HMSN-I,was synthesized by vacuum-assisted impregnation.The HMSN-I was used as inorganic filler for synthesizing Nafion/HMSN-I.The composition and structure of HMSN-I were characterized by SEM,TEM,BET and FTIR.The results show that HPW was successfully injected into the interior of the HMSN and into the mesoporous of the shell.The cell performances show that the Nafion/HMSN-I composite membrane has much higher conductivity than pristine Nafion 115membrane under identical conditions.The Nafion/HMSN-I composite membrane has a maximum output of 230 mW cm^-22 at 120°C and 50%RH,which is 3.8 times that of the conventional Nafion 115 membrane.The as-prepared composite membrane is very promising for promoting the development of high temperature and low humidity PEMFCs.