A Study on the Action of Ozone and on the Thermal Stability of Nanodiamond

Abstract

Ultradisperse detonation diamond (UDD), a nanodiamond having particle size around 4 nm has been treated with ozone in an aqueous slurry. The reaction kinetics appeared to be relatively slow and long ozonation times were needed in order to functionalize the surface of a special nanodiamond sample with a very low degree of oxidation and foreign groups. The resulting ozonated nanodiamond has been studied by FT‐IR and electronic spectroscopy. It has been shown that the ozonation of cyclohexane and adamantane can be taken as a model reaction for the ozonation of diamond. Together with ketonic groups of various nature formed on the surface of nanodiamond, the ozonation leads also to the formation of simple molecules like for instance HCOOH and HCHO which remain in the water solution and which have been detected by HPLC analysis using a diode‐array detector. The thermal stability of the nanodiamond sample has been studied by thermogravimetric analysis (TGA‐DTG) combined with differential thermal analysis (DTA) both under inert atmosphere and in air flow. The studies on thermal stability have been conducted in comparison to a sample of bulk diamond. It appears that the behavior of nanodiamond is completely different than the bulk diamond sample. For instance, under inert atmosphere and at 900°C the weight loss undergone by the nanodiamond is 11.5% while it is negligible in the case of bulk diamond under the same conditions. Similarly, in air flow the nanodiamond burns abruptly above 450°C while bulk diamond starts to burn only above 850°C. These differences have been explained in terms of different particle size and surface functionalization.

Keywords:

• Nanodiamond
• Surface
• Purification
• Oxidation
• Ozone
• Infrared spectroscopy
• Optical properties
• Thermal stability

Acknowledgments

Many thanks to ASI, the Italian Space Agency of Rome (Italy) and to RFBR, the Russian Foundation for Basic Research (Grants 01‐05‐65416 and 02‐05‐04001) for the partial financial support of the present work.