Fe-N-C catalysts,as promising non-precious metal alternatives for the oxygen reduction reaction(ORR),still suffer from severe mass transport limitations in proton exchange membrane fuel cells(PEMFCs)due to water flood...Fe-N-C catalysts,as promising non-precious metal alternatives for the oxygen reduction reaction(ORR),still suffer from severe mass transport limitations in proton exchange membrane fuel cells(PEMFCs)due to water flooding of active sites embedded in micropores.Although pore engineering through a selected template is a general strategy,the structural features of an ideal template,particularly those governing the exposure of active sites and thus affecting mass transport,remain elusive.Here,we demonstrate that low-porosity carbon templates maximize the ratio of active sites distributed at or near the surface,thereby enhancing their exposure and accessibility while reducing mass transport resistance during the ORR process.The C_(lp-1)@PPy and C_(lp-2)@PPy(PPy=polypyrrole)catalysts,derived from low-porosity carbon templates,achieve peak power densities of 0.96 and 1.03 W·cm^(-2) under H_(2)/O_(2)and 0.50 and 0.52 W·cm^(-2) under H_(2)/air,demonstrating excellent performance in PEMFC tests.Structural and electrochemical characterizations reveal that the enhanced surface exposure of active sites effectively mitigates mass transport resistance during the ORR,thereby offering a general design principle for overcoming mass transport limitations in Fe-N-C catalysts for PEMFC applications.展开更多
基金the National Key R&D Program of China(No.2024YFA1509500)the National Natural Science Foundation of China(No.22479010)+5 种基金the financial support from the Chongqing Municipal Natural Science Foundation(No.CSTB2024NSCQJQX0034)Shenzhen Science and Technology Program(No.KJZD20240903101359020)the financial support from the National Natural Science Foundation of China(No.22372004)the support from the Experimental Center of Advanced Materials of the Beijing Institute of Technologythe technical support from Biological and Medical Engineering Core Facilities of Beijing Institute of Technologythe Analysis and Testing Center of Beijing Institute of Technology.
文摘Fe-N-C catalysts,as promising non-precious metal alternatives for the oxygen reduction reaction(ORR),still suffer from severe mass transport limitations in proton exchange membrane fuel cells(PEMFCs)due to water flooding of active sites embedded in micropores.Although pore engineering through a selected template is a general strategy,the structural features of an ideal template,particularly those governing the exposure of active sites and thus affecting mass transport,remain elusive.Here,we demonstrate that low-porosity carbon templates maximize the ratio of active sites distributed at or near the surface,thereby enhancing their exposure and accessibility while reducing mass transport resistance during the ORR process.The C_(lp-1)@PPy and C_(lp-2)@PPy(PPy=polypyrrole)catalysts,derived from low-porosity carbon templates,achieve peak power densities of 0.96 and 1.03 W·cm^(-2) under H_(2)/O_(2)and 0.50 and 0.52 W·cm^(-2) under H_(2)/air,demonstrating excellent performance in PEMFC tests.Structural and electrochemical characterizations reveal that the enhanced surface exposure of active sites effectively mitigates mass transport resistance during the ORR,thereby offering a general design principle for overcoming mass transport limitations in Fe-N-C catalysts for PEMFC applications.
