Colloidal stability over months of highly crystalline high-pressure high-temperature hydrogenated nanodiamonds in water

In this study, milled nanodiamonds synthesized from HPHT diamond (MND) were successfully hydrogenated and stabilized in colloidal suspension in water over months. The optimal hydrogenation conditions correspond to a minimization of carbon/oxygen bonds and sp2/amorphous carbon at MND surface as shown by FTIR and XPS. Clean crystalline particles were observed by HR-TEM. The colloidal stability is discussed in terms of sp2 carbon and role of facets. The signature of a surface conductivity was identified by FTIR. A particular arrangement in colloidal suspension of H-MND was observed by Cryo-EM for H-MND with the formation of chain like structures extending over micron range.