Keyword: «functional groups»

The Boehm titration method was used to determine the presence of oxygen-containing functional groups in nanodiamonds obtained by grinding natural diamond (NND) and detonation synthesis (DND) before and after heat treatment. Hydroxyl, lactone and carboxyl functional groups were found in the samples. After heat treatment under these conditions, the content of acidic oxygen-containing groups in NND samples increased from 26 to 29 μmol/g, and in DND samples from 250 to 263 μmol/g. In this case, the number of carboxyl groups increases with a simultaneous decrease in the number of hydroxyl groups on the surface of nanodiamonds in both NND and DND samples. In the case of DND nanopowders, after heat treatment, the amount of lactone groups decreases from 20 to 5 μmol/g.

The effect of thermal treatment on the composition of functional groups in detonation and natural nanodiamonds was studied using X-ray photoelectron spectroscopy. It was shown that annealing in air at 400–550 °C leads to a decrease in the fraction of sp²-hybridized carbon atoms and an increase in the sp³ component. Changes in oxygen- and nitrogen-containing functional groups were revealed, indicating oxidation processes and restructuring of surface chemical bonds in nanodiamond particles.

The effect of thermal treatment on the composition of oxygen-containing functional groups in natural (NND) and detonation (DND) nanodiamonds was studied using FTIR spectroscopy and Boehm titration. It was found that annealing in air at 550 °C alters the ratio of hydroxyl and carbonyl groups, removes non-diamond carbon forms, and improves the ordering of the surface structure. The results are consistent with XPS data and confirm the effectiveness of thermal treatment for nanodiamond purification.