Abstract
AbstractDetonation nanodiamonds (DNDs) are known to be produced in aggregated clusters of a few nanometer‐sized primary crystalline particles embedded in an amorphous carbon matrix exhibiting high degree of polydispersity. A commonly accepted mechanism behind DND aggregation is the bridging of primary particles via oxygen containing functionalities. Here, we provide definitive spectroscopic evidence in favor of this working mechanism by carrying out systematic chemical compositional analysis on monodispersed DND aggregates of various sizes. Oxygen content is found to increase proportionally with the aggregate size confirming the role of oxygen containing functionalities as a cross‐linker. Solid‐state nuclear magnetic resonance data confirms these linkers to be of ether (COC) nature. Our results imply that oxygen content in DNDs can be independently tuned by varying the aggregate size, a knowledge which might benefit other applications, in addition. Next, we use this understanding to engineer the DND surfaces via an acid hydrolysis step to strip off these oxygen functionalities leading to size reduction of ca. 150 nm as‐received DND aggregates to ca. 40 nm with >90% yields, without resorting to any other pre‐ or post‐hydrolysis treatment such as surface functionalization or milling.
Highlights
The morphology of the DND bands was studied by transmission electron microscopy (TEM) and showed that they consist of aggregates of several crystalline primary particles as demonstrated in Figure 1 where the first, third, and the sixth bands are shown
We have carried out a detailed chemical compositional analysis of monodispersed DND aggregates of various sizes obtained via Rate-zonal density gradient ultracentrifugation (RZDGU)
Employing X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and SS-nuclear magnetic resonance (NMR), we find that oxygen content increases with the aggregate size, substantiating the oxygen-led-aggregation model
Summary
Detonation nanodiamonds (DNDs) are well known to aggregate.[1,2] DND aggregates (∼10–500 nm) consist of primary particles ∼4–5 nm in size, held together in a matrix of amorphous carbon.[1,3,4] Recent notable developments include observation of optical limitation effects in surface functionalized DNDs and the demonstration of energetic core-shell composites.[5,6,7,8] the potential applications of DNDs range from photonics[9] and quantum computing[10,11] to drug delivery,[12,13] they are highly size-dependent.[2] Whereas >100 nm DND aggregates would be attractive for photonics applications, the
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