Water interaction with hydrogenated and oxidized detonation nanodiamonds — Microscopic and spectroscopic analyses

Abstract

a b s t r a c tWater interaction with surface modified nanodiamonds (NDs) is critical for many possible applications of NDs e.g. in biomedicine. Here we report on investigation of water interaction with hydrogenated and oxidized detonation nanodiamonds (H-DNDs, O-DNDs) by means of Fourier transform infrared spectroscopy (FTIR), thermal analysis, and Kelvin probe force microscopy (KPFM). Higher water content (4.4%) as well as weaker interaction of water with H-DNDs are identified by thermal analysis. It is explained by hydrophobicity of the H-DND surface, as revealed by the analysis of bending and stretching vibrations of surface water in FTIR spectra. On the other hand, hydrophilic nature of O-DNDs leads to lower water content (3.1%) but stronger interaction with the O-DND surface. This is evidenced by as high as 300°C desorption temperature of the surface water from O-DNDs. KPFM analysis shows that the surface-bound water can have significant screening effect on contact potential difference (CPD) of nanodiamonds (up to 510 mV) as well as on the CPD difference between H-DNDs and O-DNDs (from 50 mV to 210 mV). Nevertheless, H-DNDs exhibit always lower work function.

High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

“…This discrepancy may have several reasons, but we suppose that the main effect comes from a hydration shell formed in water on oxidized DND surface. Such a shell of surface-bound water on DNDs3738 was reported to have thickness of about 0.6 nm39. This value agrees well with our results as the average difference between the AFM and DLS results is 1.6 ± 0.2 nm which yields a hydration shell thickness of 0.8 ± 0.1 nm.…”

Fluorescence and Physico-Chemical Properties of Hydrogenated Detonation Nanodiamonds

“…In agreement with the NEXAFS results, DND-H Anneal appears to contain less oxygen than the DND-H Plasma sample. However, at least part of this oxygen could be associated with water molecules adsorbed on the DND surface and is not necessarily chemically bound to the surface [9,44,45]. All samples show a small N1s peak at 398.1 eV, indicating the presence of ≈1-2 at% nitrogen in all samples.…”

“…FTIR spectra ( Figure 3D) also qualitatively suggest the successful hydrogenation of both DND-H Anneal and DND-H Plasma samples: the C=O peak at 1750 cm −1 disappears in both hydrogenated samples, while two CH x stretch peaks appear at 2875 cm −1 & 2930 cm −1 , which are characteristic of hydrogen termination [8,49,50]. Both O-H bending and stretching modes at 1630 cm −1 and 3400 cm −1 may indicate incomplete surface modification or be caused by adsorbed water molecules on the surface of the DNDs [9,44,45]. Another change due to hydrogenation is the appearance of a broad shoulder at ≈1550 cm −1 which is typically associated with C=C stretching [44,51,52].…”

Surface chemistry of water-dispersed detonation nanodiamonds modified by atmospheric DC plasma afterglow

“…The amount of water and difference between as-received and oxidized DNDs is in a good agreement with thermogravimetric analysis of DNDs in our prior work. 30 Note, that 2-3 at% of nitrogen was found in each sample. This is related to impurities naturally found in detonation NDs.…”