Abstract
Nanodiamonds represent a burgeoning class of carbon nanomaterials that possess favorable physical and chemical properties useful in abrasives, chemocatalysis, biomedicine, etc. Nowadays, the research on nanodiamonds has developed rapidly, with impressive control over particle size and morphology. However, the synthesis of nanodiamonds with ubiquitous nanotwinned substructure has yet to be realized. Here, we report the synthesis of nanotwin-structured nanodiamond particles from onion carbon precursors (with potassium chloride working as the isolation layer) under high pressure and high temperature conditions. The structural characterizations indicate that the synthetic nanodiamonds contain a nanotwinned substructure within individual particles, with an average twin thickness of ∼5 nm. The current work demonstrates an effective approach to nanodiamond particles with a nanotwinned substructure, which may promote applications in related areas.
Highlights
We report the synthesis of nanotwin-structured nanodiamond particles from onion carbon precursors under high pressure and high temperature conditions
The interlayer spacings in onion carbon determined from high-resolution TEM (HRTEM) measurement are 0.35–0.38 nm, slightly larger than that (0.34 nm) of graphite
The selected area electron diffraction (SAED) pattern shows diffraction rings corresponding to the crystal planes of diamond, which is in agreement with the X-ray diffraction (XRD) result
Summary
Diamond has the highest hardness and thermal conductivity, excellent wear resistance, high luminousness, and high chemical stability, leading to its wide applications in mechanics, electronics, and optics. In addition to these advantages, nanodiamonds (NDs) possess the distinctive properties of nanomaterials, such as large specific surface area and high surface activity. the non-toxic NDs exhibit good biocompatibility and feasible surface functionalizability. The unique combination of these properties makes NDs a promising material for grinding, composite coatings, chemical catalysis, and biomedicine.6–8NDs were first produced from detonation (shock wave synthesis) in the 1960s.9 In the following decades, different methods were developed to synthesize NDs, including high-energy ball milling, plasma-assisted chemical vapor deposition (CVD), autoclave synthesis from supercritical fluids, and electron irradiation of carbon onions. With a diversity of synthesis methods to NDs available, it remains a challenge to introduce ubiquitous nanotwinned substructures into individual nanodiamond particles. Diamond has the highest hardness and thermal conductivity, excellent wear resistance, high luminousness, and high chemical stability, leading to its wide applications in mechanics, electronics, and optics.. Diamond has the highest hardness and thermal conductivity, excellent wear resistance, high luminousness, and high chemical stability, leading to its wide applications in mechanics, electronics, and optics.1,2 In addition to these advantages, nanodiamonds (NDs) possess the distinctive properties of nanomaterials, such as large specific surface area and high surface activity.. NDs were first produced from detonation (shock wave synthesis) in the 1960s.9. Different methods were developed to synthesize NDs, including high-energy ball milling, plasma-assisted chemical vapor deposition (CVD), autoclave synthesis from supercritical fluids, and electron irradiation of carbon onions.. With a diversity of synthesis methods to NDs available, it remains a challenge to introduce ubiquitous nanotwinned substructures into individual nanodiamond particles. Even though twin substructures can be identified in detonation nanodiamonds (DNDs), a relatively high proportion of DND particles without twin substructures were observed, as revealed from the transmission electron microscopy (TEM) investigation.
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