科研之友
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摘要
Vesicular nitrogen doped carbon (VNC) material, with BET surface area of high up to 555 m(2) g(-1), has been prepared by pyrolyzing the polyaniline covering on the Fe2O3 nanoparticles, followed by acid leaching with H2SO4 and graphitization. For the cathodic reduction of oxygen, the catalyst exhibits excellent activity and stability. Its onset potential and half-wave potential for the oxygen reduction reaction reach 0.93 V and 0.82 V (vs. reversible hydrogen electrode) in 0.5 M H2SO4, which are comparable to the performance of commercial 20 wt% Pt/C catalyst. It is demonstrated that the air/hydrogen single cell with VNC as cathode catalyst, has an open-circuit cell potential of 0.85 V and 191 mW cm(-2) of maximum power density at cell temperature of 70 degrees C. It is suggested that the high performance of this type of catalyst results from its high active center density, which may be caused by the high surface area of the vesicular structure of the catalyst. Furthermore, we believe that the ferric oxide may act as the template of the vesicular structure, and the iron may just participate in the construction of active sites, but not as a component of the active site.
