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Direct Access to Metal or Metal Oxide Nanocrystals Integrated with One-Dimensional Nanoporous Carbons for Electrochemical Energy Storage

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journal contribution
posted on 2010-10-27, 00:00 authored by Yanyu Liang, Matthias Georg Schwab, Linjie Zhi, Enrico Mugnaioli, Ute Kolb, Xinliang Feng, Klaus Müllen
Metal and metal oxide nanocrystals have sparked great interest due to their excellent catalytic, magnetic, and electronic properties. Particularly, the integration of metallic nanocrystals and one-dimensional (1D) electronically conducting carbons to form metal−carbon hybrids can lead to enhanced physical and chemical properties or even the creation of new properties with respect to single component materials. However, direct access to thermally stable and structurally ordered 1D metal−carbon hybrids remains a primary challenge. We report an in situ fabrication of Co3O4 or Pt nanocrystals incorporated into 1D nanoporous carbons (NPCs) via an organometallic precursor-controlled thermolysis approach. The AB2-type (one diene and two dienophile) 3,4-bis(4-dodecynylphenyl)-substituted cyclopentadienone and its relevant cobalt or platinum complex are first impregnated into the nanochannels of AAO (anodic alumina oxide) membranes. The intermolecular Diels−Alder reaction of these precursor molecules affords the formation of cobalt or platinum functionalized polyphenylene skeletons. Subsequent thermolysis transforms the polyphenylene backbones into 1D nanoporous carbonaceous frameworks, while the metallic moieties are reduced into Co or Pt nanocrystals, respectively. After removal of the AAO template, 1D NPCs/Co3O4 or NPCs/Pt are obtained, for which structural characterizations reveal that high-quality Co3O4 or Pt nanocrystals are distributed homogeneously within carbon frameworks. These unique 1D metal−carbon hybrids exhibit a promising potential in electrochemical energy storage. NPCs/Co3O4 is evaluated as an electrode material in a supercapacitor, for which Co3O4 nanocrystals contribute an exceptionally high gravimetric capacitance value of 1066 F g−1. NPCs/Pt is applied as an electrocatalyst showing excellent catalytic efficiency toward methanol oxidation in comparison to commercial E-TEK (Pt/C) catalyst.