Activity, Performance, and Durability for the Reduction of Oxygen in PEM Fuel Cells, of Fe/N/C Electrocatalysts Obtained from the Pyrolysis of Metal-Organic-Framework and Iron Porphyrin Precursors

作者：Yang Lijun; Larouche Nicholas; Chenitz Regis; Zhang Gaixia; Lefevre Michel; Dodelet Jean Pol^*

来源：Electrochimica Acta, 2015, 159: 184-197.

DOI：10.1016/j.electacta.2015.01.201

• Catalyst
• O-2 reduction
• Proton Exchange Membrane Fuel Cell
• ZIF-8
• ClFeTMPP

Fe/N/Ctype catalysts have been produced by ballmilling ZIF-8 (a metal-organic-framework) and a chloroiron-tetramethoxyporphyrin (ClFeTMPP). The resulting material was first pyrolyzed in Ar at temperatures ranging from 850 to 1150 degrees C, then in NH3 at 950 degrees C in order to produce two series of catalysts: the Ar and the Ar + NH3 ones. They were labeled NC Por_x-T Ar or NC Por_x-T Ar + NH3, where x is the nominal Fe loading in wt% and T is the temperature of the first pyrolysis in Ar. At 80 degrees C inH(2)/O-2 fuel cell, the most active and performing catalyst is NC Por_0.8-1050 Ar + NH3. All NC Por_0.8-T Ar + NH3 catalysts with T comprised between 850 and 1050 degrees C display the same instability behavior. The only catalyst showing an improvement in durability is NC Por_0.8-1150 Ar + NH3. It is proposed that the drastic change in durability upon increasing the first pyrolysis temperature, from 1050 to 1150 degrees C in Ar, is attributable to an important decrease in the heteroatom content (a drop of 32% for both N and O atoms) of the catalyst upon graphitization, reducing the hydrophilic character of its carbonaceous support and decreasing the possibility of water flooding its catalytic sites, particularly the sites located in micropores.

• 出版日期2015-3-20