From Well‐Defined Carbon‐Rich Precursors to Monodisperse Carbon Particles with Hierarchic Structures

Abstract

The creation of nanoscale particles with well-defined structures has long been considered as a promising approach to generate materials with novel properties. Carbonaceous nanoparticles (CNPs) with defined architectures, such as carbon nanotubes (CNTs), C 60 , carbon onions, carbon spheres, and carbon rods are particularly attractive owing to their unique electronic properties and many potential applications.[1] At the same time, when these CNPs are regularly organized, additional functions appear.[2] Such materials are believed to have hierarchic structures, [3] in which the organization of the CNPs forms the first-order structure (FOS) and the configuration of the single CNP forms the second-or higher-order structure (SOS or HOS). Because both the FOS and HOS are responsible for the properties of the bulk material, simple methods to prepare multidimensional carbon materials with hierarchic structures are needed. Template methods are commonly used to produce 3D order in which the silica opal or inverse opal crystals are the most frequently selected templates. [3b,4] Carbonaceous materials have been prepared in these templates by using sucrose or phenolic reactants as precursors, [5] but only amorphous CNPs were obtained. Alternatively, chemical vapor deposition (CVD) over inverse opals was reported to produce crystalline carbons.[4a] Unfortunately, such CVD procedures resulted in inverse carbon opals, not CNPs, and the control over the carbon structures was limited. The preparation of well-defined CNPs with 3D organization is still a challenge owing to the difficulties of controlling molecular interactions at high temperatures. Recent studies on solid-state pyrolysis (SSP) have implied that the structures of CNPs could be controlled by choosing well-defined organometallic precursors. [6][7][8][9] Thus, CNTs were obtained in high yield from SSP of diphenylethyne-metal complexes; [6] while dicobalthexacarbonyl-functionalized poly(p-phenyleneethynylene) afforded carbon-cobalt spheres.[7] Our previous SSP of dendritic polyphenylene-cobalt complexes resulted in uniformly shaped carbon-cobalt nanorods with rectangular cross sections, [8] whereas disclike structures with extended p-systems furnished bamboolike CNTs and carbon shell/metal core cablelike structures. [9] However, in all these experiments, the metal catalysts play a more important role for product formation than the chemical structure of the precursors; and these processes incorporate metals into the pyrolysis products. To prepare metal-free CNPs with defined structures, the design of the precursors requires more attention. Our recent attempts at precursordefined pyrolyses (PDP) produced graphitic nanotubes with brick-walled structures [10] and CNTs with 3D porous-walled structures.[11]

Hollow Micro‐/Nanostructures: Synthesis and Applications

“…Macroporous templates of other materials with very different surface properties (e.g., silica and carbon) have also been employed, [86,87] which further expand the diversity of hollow structures that can be prepared by the lost-wax approach. [88] Despite its elegance and versatility, shortcomings of the lost-wax approach include the relatively large number of steps required, the low efficiency of each step, and the stringent controls required in each step to secure the desired structures. As such, the method is not easily applied to X. W. Lou et al / Hollow Micro-/Nanostructures: Synthesis and Applications Figure 6.…”

Application of helium ion microscopy to nanostructured polymer materials

“…The filler may be of inorganic or polymer nature and can be of an isotropic (nanoparticles), anisotropic (nanowires, nanofibers, nanotubes), or hierarchical (dendrimers) shape. The nanofiller can be synthesized in situ in functional polymer matrix or can be dispersed in it during fabrication protocols (solution or melt mixing) [35]. Carbon nanotubes (CNTs) have been introduced more than two decades ago and possess unique mechanical, electrical, and thermal conductivity properties, which makes them very attractive as a filler material for developing conducting polymer composites for modern engineering applications.…”

Precursor‐Controlled Formation of Novel Carbon/Metal and Carbon/Metal Oxide Nanocomposites

“…[10] Recently, the solid-state pyrolysis of well-defined, carbon-rich precursors into carbonaceous particles with unique structures demonstrated the close relationship between precursor and product, [11] which stimulated the concept of precursor-controlled thermolysis towards defined carbon materials. [12] Herein, several examples are described to illustrate the power of this concept. For the first time, CMCs with various structures, for example, a one-dimensional carbon/cobalt hybrid wrapped by carbon nanotubes (CNTs), spherical carbon/cobalt composites covered by CNTs, and small cobaltcore/carbon-shell particles, were obtained via solid-state pyrolysis of very simple, but structurally defined, precursors.…”