The presence of large amounts of nondiamond carbon in detonation-synthesized nanodiamond (ND) severely limits applications of this exciting nanomaterial. We report on a simple and environmentally friendly route involving oxidation in air to selectively remove sp2-bonded carbon from ND. Thermogravimetric analysis and in situ Raman spectroscopy shows that sp2 and sp3 carbon species oxidize with different rates at 375−450 °C and reveals a narrow temperature range of 400−430 °C in which the oxidation of sp2-bonded carbon occurs with no or minimal loss of diamond. X-ray absorption near-edge structure spectroscopy detects an increase of up to 2 orders of magnitude in the sp3/sp2 ratio after oxidation. The content of up to 96% of sp3-bonded carbon in the oxidized samples is comparable to that found in microcrystalline diamond and is unprecedented for ND powders. Transmission electron microscopy and Fourier transform infrared spectroscopy studies show high purity 5-nm ND particles covered by oxygen-containing sur...

Control of sp2/sp3 carbon ratio and surface chemistry of nanodiamond powders by selective oxidation in air.

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

The generation of reactive oxygen species (ROS) is an important mechanism of nanomaterial toxicity. We found that Prussian blue nanoparticles (PBNPs) can effectively scavenge ROS via multienzyme-like activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) activity. Instead of producing hydroxyl radicals (•OH) through the Fenton reaction, PBNPs were shown to be POD mimetics that can inhibit •OH generation. We theorized for the first time that the multienzyme-like activities of PBNPs were likely caused by the abundant redox potentials of their different forms, making them efficient electron transporters. To study the ROS scavenging ability of PBNPs, a series of in vitro ROS-generating models was established using chemicals, UV irradiation, oxidized low-density lipoprotein, high glucose contents, and oxygen glucose deprivation and reperfusion. To demonstrate the ROS scavenging ability of PBNPs, an in vivo inflammation model was established using lipoproteins in Institute for Cance...

Prussian Blue Nanoparticles as Multienzyme Mimetics and Reactive Oxygen Species Scavengers.

Adsorption of dyes by nanomaterials: Recent developments and adsorption mechanisms

This study introduces graphited nanodiamond (G-ND) as an environmentally friendly, easy-to-regenerate, and cost-effective alternative catalyst to activate persulfate (i.e., peroxymonosulfate (PMS) and peroxydisulfate (PDS)) and oxidize organic compounds in water. The G-ND was found to be superior for persulfate activation to other benchmark carbon materials such as graphite, graphene, fullerene, and carbon nanotubes. The G-ND/persulfate showed selective reactivity toward phenolic compounds and some pharmaceuticals, and the degradation kinetics were not inhibited by the presence of oxidant scavengers and natural organic matter. These results indicate that radical intermediates such as sulfate radical anion and hydroxyl radical are not majorly responsible for this persulfate-driven oxidation of organic compounds. The findings from linear sweep voltammetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectroscopy analyses suggest that the both pers...

Activation of Persulfates by Graphitized Nanodiamonds for Removal of Organic Compounds

FTIR study of ultradispersed diamond powder synthesized by explosive detonation

Preparation of T-carbon by plasma enhanced chemical vapor deposition

Single crystal diamonds were deposited on high pressure high temperature (HPHT) substrate with high growth rate, up to 18.5 μm/h, by using dual radio-frequency inductive coupled plasma jet. The methane flux was found to influence the growth rate of single crystal diamond. The reason for this might be ascribed to the electron temperature increase, raising the flux of methane, based on the plasma diagnosis results by optical emission spectra (OES). The results of Raman spectroscopy and the X-ray rocking-curve indicated that as-deposited diamonds are of good quality.

https://www.mdpi.com/2073-4352/9/1/32/pdf

Single Crystal Diamond Deposited by Dual Radio-Frequency Plasma Jet CVD with High Growth Rate

Application of dual radio frequency inductive coupled plasma into CVD diamond growth

The invention discloses a method for machinery polishing of monocrystal diamond with assistance of metal power, and belongs to the technical field of diamond material processing. Mixed power of transition group metal powder and diamond micro-powder is adopted as a monocrystal diamond mechanical polishing medium, and the mass ratio between the metal power and diamond power is 1:0.5 to 1:10; the mixed power of the metal power and the diamond power uniformly coats the surface of a high-speed rotary iron casting disc, and the rotating speed of a polishing disc is 1000 r/min to 5000 r/min; the monocrystal diamond is fixed by a clamp capable of adjusting the angle, pressure of 0.1 Kg to 2- Kg is applied, and during polishing, the polishing surface of the monocrystal diamond is in contact with the polishing disc, and violent friction with the linear speed of being 10 m/s to 100 m/s is generated; and the polishing process is carried out in the crystal direction of the crystal face [100] of themonocrystal diamond (100). The method for machinery polishing of the monocrystal diamond with assistance of the metal power has the advantage that a new economical and efficient approach is providedfor efficient processing of the monocrystal diamond.

Kai Xu

Papers

FTIR study of ultradispersed diamond powder synthesized by explosive detonation

Preparation of T-carbon by plasma enhanced chemical vapor deposition

Single Crystal Diamond Deposited by Dual Radio-Frequency Plasma Jet CVD with High Growth Rate

Application of dual radio frequency inductive coupled plasma into CVD diamond growth

Method for machinery polishing of monocrystal diamond with assistance of metal power