Bai Lu, Liu Jingjun, Gu Weiwei, Song Ye, Wang Feng
Static Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Electrochemical Process and Technology for Materials , Beijing University of Chemical Technology , Beijing 100029 , P. R. China.
ACS Appl Mater Interfaces. 2019 May 8;11(18):16452-16460. doi: 10.1021/acsami.8b20619. Epub 2019 Apr 26.
Controllable pyrolysis of collapsible metal-organic frameworks (MOFs) into carbon-based nanostructures without obvious collapse and aggregation is of importance for the fabrication of well catalytic active and durable carbon-based catalysts for the oxygen reduction reaction (ORR). Herein, we fabricate morphology-controlled carbon-based nanostructures derived from the Co-based zeolitic imidazolate framework (ZIF-67) that epitaxially grows on layered lanthanum oxycarbonate (LaOCO) as a structure-oriented template, followed by pyrolysis at 800 °C. These synthesized carbon-based nanostructures show a well-defined dodecahedron morphology and vertical array on the template surface. In 0.1 M KOH solution, the ORR activity and durability of the carbon-based nanostructures are not only much higher than those obtained by pyrolytic carbons derived from pure ZIF-67 but also exceed commercial Pt/C (20 wt %, Pt). The significantly improved ORR performance can be ascribed to the increased Co-N level, high specific surface area, and graphitization of the pyrolytic carbon, caused by the introduction of the LaOCO phase into the composite catalyst. Therefore, using LaOCO as the template may be a smart synthetic strategy for MOF-derived nanocarbons with a controlled morphology and composition for energy storages and conversions.
将可塌陷的金属有机框架（MOF）可控热解为碳基纳米结构，且无明显塌陷和聚集，这对于制备用于氧还原反应（ORR）的具有良好催化活性和耐久性的碳基催化剂至关重要。在此，我们制备了由钴基金属有机框架（ZIF-67）衍生而来的形态可控的碳基纳米结构，该ZIF-67在层状碳酸镧（LaOCO）上外延生长作为结构导向模板，随后在800℃下进行热解。这些合成的碳基纳米结构在模板表面呈现出明确的十二面体形态和垂直阵列。在0.1 M KOH溶液中，碳基纳米结构的ORR活性和耐久性不仅远高于由纯ZIF-67热解得到的碳，而且超过了商业Pt/C（20 wt%，Pt）。ORR性能的显著提高可归因于复合催化剂中引入LaOCO相导致的Co-N含量增加、高比表面积和热解碳的石墨化。因此，使用LaOCO作为模板可能是一种制备具有可控形态和组成的用于能量存储和转换的MOF衍生纳米碳的明智合成策略。
