| Résumé | Three mesoporous carbon spheres (MPCs) are synthesized using three different templates with sizes of22, 35 and 50 nm, respectively. These three MPC materials are then used as catalyst supports to formthree catalysts (Fe-N X/MPC22, Fe-NX/MPC35, and Fe-NX/MPC50) for oxygen reduction reaction (ORR).SEM images show that after catalyst deposition on the synthesized mesoporous carbon, the sphericalmorphology of mesoporous carbon is well maintained. EDX measurements show that the average Fecontent in the formed mesoporous carbon supported catalysts is very close to the initial synthesis valueof 5 wt%. BET and linear scanning voltammetry are used for characterizing the surface area and electro-chemical properties of the synthesized MPC support materials to study the effect of template size (orpore size). The results show that mesoporous carbon with template size of 50 nm has the largest BETsurface area (2125 m2/g). The measurement results show that all ORR activities of these three MPC sup-ported catalysts are higher than that of commercially available carbon supported one, demonstratingthe advantage of MPC support. Among these three catalysts, the performance order is Fe-N X/MPC50 > Fe-NX/MPC35 > Fe-NX/MPC22, showing the effect of template size on the ORR activity of the catalyst, i.e., theORR activity increases when the template size (or MPC pore size) is increased. The results also clearlyindicate that the mesopores in the range of 22-50 nm can still affect the ORR activity, suggesting thatmesopores are also important in the formation of ORR active sites besides micropores. |
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