Abstract
Hydrogenated detonation nanodiamonds are of great interest for emerging applications in areas from biology and medicine to lubrication. Here, we compare the two main hydrogenation techniques—annealing in hydrogen and plasma-assisted hydrogenation—for the creation of detonation nanodiamonds with a hydrogen terminated surface from the same starting material. Synchrotron-based soft X-ray spectroscopy, infrared absorption spectroscopy, and electron energy loss spectroscopy were employed to quantify diamond and non-diamond carbon contents and determine the surface chemistries of all samples. Dynamic light scattering was used to study the particles’ colloidal properties in water. For the first time, steady-state and time-resolved fluorescence spectroscopy analysis at temperatures from room temperature down to 10 K was performed to investigate the particles’ fluorescence properties. Our results show that both hydrogenation techniques produce hydrogenated detonation nanodiamonds with overall similar physico-chemical and fluorescence properties.
Highlights
Detonation nanodiamonds (DNDs) have attracted great attention in the scientific and industrial communities in the past decade [1,2]
While the DND Oxidized starting material is known to contain less than 5% non-diamond carbon [24], both hydrogenation techniques can lead to graphitization of the particles due to elevated temperatures of the processes
energy loss spectroscopy (EELS) and NEXAFS experiments suggest that both hydrogenation techniques induce partial graphitization of the oxidized starting material and increase the amount of sp2 -hybridized carbon from 4% in the starting material to between 20% and 30%
Summary
Detonation nanodiamonds (DNDs) have attracted great attention in the scientific and industrial communities in the past decade [1,2]. Many questions about their exact nanoscale composition, crystal structure, and surface properties remain unanswered, necessitating continued efforts in the detailed material characterization of DNDs. C 2020, 6, 7; doi:10.3390/c6010007 www.mdpi.com/journal/carbon. The two main routes towards the hydrogenation of DNDs are based on high-temperature annealing in molecular hydrogen gas [8,14] and plasma-assisted modification [15]. Both make use of the high reactivity of hydrogen with carbon atoms on the diamond surface, but processing times, temperatures, experimental setup, and atmosphere differ significantly [16]
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