Solid State NMR study of nanodiamond surface chemistry

Using hydrogen isotope incorporation as a tool to unravel the surfaces of hydrogen-treated nanodiamonds

“…The previous DND annealed under hydrogen, deuterium or tritium atmosphere were then studied by Magic Angle Spinning (MAS) NMR to better investigate the nature of the carbon structure and the C-H bonds 38,39 .The 13 C MAS NMR spectra are shown in Figure 6a for hydrogen-treated and deuterium-treated DND (with or without pre-oxidation). Dashed lines highlight the positions of the three main peaks observed, in agreement with previous studies [38][39][40][41][42] . The most intense one, located at around 34 ppm, is generally assigned to carbon atoms that are in the DND crystalline core (narrow component of the peak) and in the shell near the surface that covers the diamond core.…”

Preparation and properties of multilayered polymer/nanodiamond composites via an in situ technique

“…The detonation soot was subjected to a mixture of hydrofluoric acid (40 wt%) and fuming nitric acid comprised in the ratio 25/75 wt%, to remove the metallic impurities. Further elimination of non-diamond sp 2 phase was achieved through oxidation in HNO 3 at 230°C and 100 atm pressure in a titanium alloy reactor [33][34][35].…”

Studies of Energy-Relevant Materials by Nuclear Magnetic Resonance

“…The aromatic-carbon signal is detected most clearly in a reference material where such carbon has been generated by heat treatment at 800 • C, generally consistent with Raman, XPS, and NMR studies of slightly pyrolyzed detonation nanodiamond. [224, 235, 362-364, 368, 369] The location of the sp 2 -hybridized carbons at the nanodiamond particle surface is confirmed by probing their distance to 1 H. The signals of C=O and COO carbons, not detected in previous NMR studies [194,227,[230][231][232][233][234][235] and therefore not considered in NMRbased models of nanodiamond, [194,231] are also observed. By quantifying the 13 C NMR signals of sp 3 -hybridized C-H and C-OH surface carbons, we provide a complementary upper limit to the sp 2 -hybridized surface carbon fraction.…”

“…[181,[362][363][364] In addition, other 13 C NMR studies of purified detonation nanodiamond also have not shown signals of aromatic carbons (i.e, peaks between 115 and 150 ppm that are not spinning sidebands). [230,[232][233][234][235] Nevertheless, models of detonation nanodiamond with more than 40% of the particle surface covered by an aromatic shell, containing > 10% of all C (see calculation below), are still being put forward even by experts in carbon materials. [147,150] This appears to be mostly based on small pre-edge X-ray absorption near-edge structure spectroscopy (XANES) peaks.…”

“…Still, it is a weakness of the previous 13 C NMR analyses of detonation nanodiamond [194,227,[230][231][232][233][234][235] that an aromatic-carbon signal was not identified and that signals of C=O groups seen in XANES and IR spectra were not detected. In this paper, we overcome this shortcoming and show that NMR can detect a few percent of sp 2 -hybridized and ∼1% aromatic carbon in nanodiamond.…”