Transformation of Nanodiamonds to Onion-like Carbons by Ambient Electrospray Deposition

Abstract

Onion-like carbons (OLCs) are a class of fullerene-like circular nanoallotropes of carbon, typically synthesized from nanodiamond (ND) via thermal annealing, plasma spraying, and laser ablation. These methods require high temperature, high vacuum, or inert gas. Here, we report an ambient electrospray deposition (AESD) process to transform NDs (11 ± 1 nm in size) into OLCs (50 ± 13 nm in size) in water. Transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the characterization of NDs and OLCs. High-resolution TEM images showed an increased interplanar spacing from ND (0.23 nm) to OLC (0.39 nm). Raman spectra showed a shift in the ND peak from 1336 cm–1 to D-band at 1349 cm–1, and XPS quantitatively estimated an increase in the graphitization ratio (sp2/sp3) from 0.95 to 3.16 after AESD. Comparison of electrospray with sonic spray confirmed that such a transformation required an external voltage as well. AESD was also performed for NDs dispersed in ethanol and acetonitrile, which showed a solvent-dependent transformation.

Fluorescent Nanocarbons: From Synthesis and Structure to Cancer Imaging and Therapy

“…Since the initial discovery of CNOs, many attempts have been made to identify the reaction conditions that yield high-purity CNOs in large quantities. These attempts have employed numerous methods using various raw-carbon precursors to synthesize CNOs, including annealing, [191] arc discharge, [192] gas-liquid detonation, [193] electrochemical, [194] CVD, [195] ambient electrospray deposition, [196] and plasma-spray from NDs. [197,198] However, our thorough analysis of the literature revealed that amongst these methods, only a few techniques have occupied the main streams of current research due to their substantial potential in producing significant quantities of CNOs that might meet the stringent demands of commercial production.…”

Facile Synthesis of Triazoles using Electrospray‐Deposited Copper Nanomaterials to Catalyze Azide‐Alkyne Cycloaddition (AAC) Click Reactions

“…[1][2][3][4][5][6][7][8] Electrospray deposition (ESD) of microdroplets under ambient conditions is emerging as a new synthetic method for a range of nanomaterials including nanoparticles (NPs), [9] nanobrushes, [10] nanowires, [11,12] nanoclusters, [13,14] nanoplatelets or nanopyramids, [15] nanosheets, [16,17] monodispersed nanoparticles, [18] and nanosized onion-like carbon (OLC). [19] The properties and structures of these nanomaterials are highly dependent on the choice of collecting surfaces which can be flat metal surfaces, [15] Indium Tin Oxide (ITO) plates, [18,19] water films, [17] MoS 2 nanosheets, [16] Te nanowires, [20] or TEM grids. [10] Metal nanostructures are of great interest owing to their catalytic properties.…”