Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol

Abstract

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm2) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C–Hx band intensities and an increase of the C–O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp3 to sp2 carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes.

Utilizing Constant Energy Difference between sp-Peak and C 1s Core Level in Photoelectron Spectra for Unambiguous Identification and Quantification of Diamond Phase in Nanodiamonds

“…Fitted components are shown for RT samples exclusively. The core level shifts and component assignments to bond types are similar to those of the reference sample in Figure 1 and in agreement with our prior studies [4,9,19,33]. The Cx component of DND-H sample spectra also involves contributions from C-N bonds.…”

“…The recent investigation of graphitization on DND-H samples through laser irradiation was reported [33]. The study indicated an increase in the concentration of the C sp 2 phase with longer irradiation times, while the concentration of defects or C-N bonds remained nearly constant.…”

“…In the existing literature, it is attributed to photoemission from carbon atoms situated within various defects [28][29][30], from hydrogen bonded to carbon atoms, denoted as C-H x [15], where x ≥ 2 [19,31,32]. High intensity of this component was observed in the C 1s spectra of DND samples [29,33]. Considering this complexity, calibrating the peak maxima of the C 1s line by assigning either the positions to the sp 2 , sp 3 components or to the sp 3 , C-H x components is not straightforward due to the similarity of the chemical shifts in both cases.…”

Oxidized Detonation Nanodiamonds Act as an Efficient Metal‐Free Photocatalyst to Produce Hydrogen Under Solar Irradiation

“…Several components may take place in this area and contribute to this band, including residues of carbonyls stretching modes (1670 cm −1 ), OH bending modes, and CC stretching modes resulting from reconstructions at the surface of H‐DND. [ 24 ] The peak located at 1330 cm −1 is assigned to CC diamond lattice made visible in FTIR due to substitutional nitrogen incorporated during the detonation synthesis (1.5–2 at% according to XPS measurements). [ 25 ] Hidden by the carbon–oxygen stretching modes on Ox‐DND spectrum, this peak is revealed after their desorption and signs for diamond core of DND.…”