Fabrication of free-standing pure carbon-based composite material with the combination of sp2–sp3 hybridizations

Composite structures have been in a center of interest for many decades. Carbon–carbon composites combine different carbon-based allotropes. Combining different carbon structures each with its unique property results in a new composite material with designed properties. In this contribution we present a technological procedure for preparation of a new flexible material consisting of single-wall carbon nanotubes (SWNTs) and nanocrystalline diamond (NCD). The fabrication process starts from the preparation of a paper made of SWNTs bundles followed by the CVD-growth of NCD in the interior of the SWNT paper. Keeping balance between the two competing processes during the CVD, i.e. growth of diamond particles versus etching SWNTs, is found as a key factor for the formation of a compact SWNT/NCD composite material. From a technological point of view, both processes are influenced mainly by the CVD conditions (temperature, gas composition, etc.) and/or substrate pretreatment. The essential idea of the diamond integration into the SWNT paper is demonstrated and discussed in more details. The morphology and structural aspects of the prepared composite material are further characterized by scanning electron microscopy and Raman spectroscopy.