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首页> 外文期刊>Catalysis science & technology >Hierarchically porous Fe-N-C nanospindles derived from a porphyrinic coordination network for oxygen reduction reaction
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Hierarchically porous Fe-N-C nanospindles derived from a porphyrinic coordination network for oxygen reduction reaction

机译：分层次多孔Fe-N-C nanospindles派生从porphyrinic协调网络氧还原反应

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摘要

We report the size and morphology-controlled synthesis of PCN-222 crystals, a class of zirconium-based iron porphyrinic coordination networks, and their pyrolytic derivation of hierarchically porous Fe-N-C electrocatalysts for the oxygen reduction reaction (ORR). By optimizing precursor concentrations, nanometer-scaled and spindle-shaped PCN-222 crystals are obtained through a solvothermal method. A NaCl salt-assisted pyrolysis is employed to convert the PCN-222 crystals to an Fe-N-C catalyst, so as to inherit the nanospindle morphology and the Fe-N coordination structure in the PCN precursor, and at the same time to increase the graphitization degree. A post-activation procedure using concentrated sulfuric acid is further designed to induce a controlled NaCl removal and carbon etching process that optimizes the porous structures and surface properties of the final nanospindle Fe-N-C catalyst. The reaction between the concentrated sulfuric acid and NaCl produces heat to activate acid etching of carbon, and on the other hand consumes the acid to prevent the carbon from over-etching. The unique nanospindle shape and hierarchically porous structure allow efficient exposure of the high-density active sites and their accessibility to reactants, while the high degree of graphitization ensures efficient conduction of electrons involved in the electrocatalytic reaction and good stability of the carbon matrix during the electrocatalytic processes. Based on the results, the as-prepared Fe-N-C catalyst exhibits remarkable ORR performance, with a half-wave potential that is ca. 30 mV more positive than that of the state-of-the-art Pt catalyst, and excellent stability in alkaline solution, as well as an ORR activity comparable to Pt in acid solution.
机译：我们报告的大小和morphology-controlledpcn - 222的合成水晶,一个类zirconium-based铁porphyrinic协调网络,及其热解的推导分层次多孔Fe-N-C electrocatalysts氧还原反应(ORR)。优化前体的浓度,纳米级和纺锤形pcn - 222通过solvothermal晶体了方法。使用pcn - 222晶体转换为一个Fe-N-C催化剂,以承受nanospindle形态学和Fe-N协调结构(PCN的前兆,以及基督教民主党的在同一时间石墨化程度增加。激活后程序使用集中硫酸是进一步设计的诱导除氯化钠和碳腐蚀控制多孔结构和优化的过程最终nanospindle的表面性质Fe-N-C催化剂。浓硫酸和氯化钠会产生热量激活酸蚀刻的碳,另一方面消耗酸防止从over-etching碳。形状和分层多孔结构允许高密度活跃的有效接触反应物和可访问性网站,高度石墨化的保证高效的电子参与导电electrocatalytic反应和良好的稳定性在electrocatalytic碳矩阵流程。Fe-N-C催化剂表现出非凡的奥尔性能的半波电位ca。30 mV的比这更积极最先进的Pt催化剂,和优秀的稳定的碱性溶液,以及一个奥尔活动与Pt酸溶液。

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