Nanodiamonds (NDs) are members of the diverse structural family of nanocarbons that includes many varieties based on synthesis conditions, post-synthesis processes, and modifications. First studied in detail beginning in the 1960s in Russia, NDs have now gained world-wide attention due to their inexpensive large-scale synthesis based on the detonation of carbon-containing explosives, small primary particle size (∼ 4 to 5 nm) with narrow size distribution, facile surface functionalization including bio-conjugation, as well as high biocompatibility. It is anticipated that the attractive properties of NDs will be exploited for the development of therapeutic agents for diagnostic probes, delivery vehicles, gene therapy, anti-viral and anti-bacterial treatments, tissue scaffolds, and novel medical devices such as nanorobots. Additionally, biotechnology applications have shown the prospective use of NDs for bioanalytical purposes, such as protein purification or fluorescent biolabeling. This review critically e...

Nanodiamond Particles: Properties and Perspectives for Bioapplications

Carbon onions are a relatively new member of the carbon nanomaterials family. They consist of multiple concentric fullerene-like carbon shells which are highly defective and disordered. Due to their small size of typically below 10 nm, the large external surface area, and high conductivity they are used for supercapacitor applications. As electrode materials, carbon onions provide fast charge/discharge rates resulting in high specific power but present comparatively low specific energy. They improve the performance of activated carbon electrodes as conductive additives and show suitable properties as substrates for redox-active materials. This review provides a critical discussion of the electrochemical properties of different types of carbon onions as electrode materials. It also compares the general advantages and disadvantages of different carbon onion synthesis methods. The physical and chemical properties of carbon onions, in particular nanodiamond-derived carbon onions, are described with emphasis on those parameters especially important for electrochemical energy storage systems, including the structure, conductivity, and porosity. Although the primary focus of current research is on electrode materials for supercapacitors, the use of carbon onions as conductive additives and for redox-active species is also discussed.

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Review: carbon onions for electrochemical energy storage

The review is devoted to nanodiamond as a member of new nanocarbon allotropes. The past results related to the main features of detonation technology for producing nanodiamond are highlighted. Effects of technology on the structure of nanodiamond particles as well as functionalization of nanodiamond surface to chemical properties are discussed. The real structure of single nanodiamond particles has been critically reviewed and its aggregation problem emphasized. Several applications of nanodiamonds mainly as precursors for CVD diamond film growth, for forming new magnetic nanomaterials and field electron emitters are reviewed. As a result, the availability of nanodiamonds as attractive building blocks for nanotechnology is concluded.

https://iopscience.iop.org/article/10.1088/0022-3727/40/20/S14/pdf

New prospects and frontiers of nanodiamond clusters

Carbon nano-onions: Unique carbon nanostructures with fascinating properties and their potential applications

A stable suspension of single ultrananocrystalline diamond particles

The paper reports on a study of the effect of annealing in hydrogen on the structural phase transition in clusters of ultradisperse diamond (UDD) obtained by the detonation method. The samples studied were of two types, namely, prepared by the “dry” and “wet” techniques, which differ in the cooling rate of the detonation products and, accordingly, in the structure of the diamond nanocluster shell. It is shown that, irrespective of the type of synthesis, the relative content of the diamond (sp3) phase increases within the anneal temperature range of 450 to 750°C, the increase being more pronounced in the samples prepared by “dry” synthesis. A model accounting for the observed structural transformation processes is discussed. A hypothesis of the possibility of compacting UDD clusters into bulk single crystals is put forward.

Effect of hydrogen on the structure of ultradisperse diamond

Transformation of the chemical composition and electron structure of graphite oxide (GO) nanolayers as a result of their annealing in hydrogen has been studied by X-ray photoelectron spectroscopy using synchrotron radiation. It is established that both the chemical composition and bandgap width of GO can be controlled by varying the temperature and duration of heat treatment. By this means, the properties of GO nanolayers can be smoothly changed from dielectric to semiconductor.

Controlling graphite oxide bandgap width by reduction in hydrogen

Porous silicon layers with introduced carbon-containing substances (fullerenes, ultradisperse diamond, carbohydrates) have been studied. It was found that high-temperature annealing of such layers in a hydrogen atmosphere leads to substantial transformation of the photoluminescence spectra. It is assumed that this results from the formation of cubic silicon carbide crystallites and the occurrence of the quantum-confinement effect in these crystallites.

Preparation and study of carbidized porous silicon

The possibility of obtaining thin (1500–3000 A) layers of ultradisperse diamond from an aqueous suspension is reported and the first results of studies of its optical properties are presented. It is deduced from an analysis of the optical absorption spectra of layers of ultradisperse diamond that the band gap of ultradisperse diamond is 2.06 eV. The luminescence spectra of ultradisperse diamond reveal a characteristic line with a peak at 363.7 nm.

Optical properties of layers of ultradisperse diamond obtained from an aqueous suspension

The interaction of a matrix of silicon nanocrystallites (porous silicon layer) with embedded fullerene molecules C60 was studied. The degradation of fullerene-containing layers as a result of irradiation with a strongly absorbed laser light was explored. It is shown that the layers with highest stability are obtained after high-temperature annealing in hydrogen. In this case, the photoluminescence spectra remain virtually unchanged when the layers are kept in air and irradiated with a high-intensity laser irradiation. Possible mechanisms of the phenomena studied are discussed.

S. P. Vul

Papers

Effect of hydrogen on the structure of ultradisperse diamond

Controlling graphite oxide bandgap width by reduction in hydrogen

Preparation and study of carbidized porous silicon

Optical properties of layers of ultradisperse diamond obtained from an aqueous suspension

Effect of a fullerene coating on the photoluminescence of porous silicon