Nanodiamonds from coal under ambient conditions

Abstract

Coal is the most abundant energy resource, but it is only useful for producing energy via combustion due to its structural characteristics. However, coal is also inexpensive and is the most plentiful and readily available carbon source material for the production of nanodiamonds compared with the most widely used solid carbon source, high-purity graphite, and the high-purity hydrocarbon gas precursor, methane. Here, we report a simple and green top-down strategy for synthesizing nanodiamonds with a cubic phase and a mean size of 3 nm from various types of coal at atmospheric pressure and room temperature using a novel process involving laser ablation in liquid. Furthermore, we have systematically studied the process of phase transformation from coal to nanodiamonds using nucleation thermodynamics, growth kinetics and structural stability. The synthesized nanodiamonds have turned out to be soluble monodisperse colloids that exhibit strong and stable fluorescence both in alcohol and in water. These results provide a route for producing nanodiamonds from inexpensive and abundant coal.

Carbyne with finite length: The one-dimensional sp carbon

“…It turned out that the peaks were located at 558.1 and 563.3 nm in the emission spectrum ( Fig. 6C ), corresponding to the C 2 swan band for Δ v = −1 ( 28 ) arising from transitions between the electronic states d 3 Π g and a 3 Π u ( 29 ) and providing straightforward evidence for the formation of C 2 molecules in our case. In addition, we collected the spectra of the other kinds of solvent that were similar to alcohol, including methanol, acetone, n -propanol, and isopropanol ( Fig.…”

Nanodiamond‐Embedded p‐Type Copper(I) Oxide Nanocrystals for Broad‐Spectrum Photocatalytic Hydrogen Evolution

“…[ 16,17 ] X-ray diffraction (XRD) patterns of the as-prepared NDs and graphite precursor are presented in Figure 1 a, and indicate the phase transformation of graphite (PDF#26-1079) to diamond (PDF#43-1104). [ 16,17 ] X-ray diffraction (XRD) patterns of the as-prepared NDs and graphite precursor are presented in Figure 1 a, and indicate the phase transformation of graphite (PDF#26-1079) to diamond (PDF#43-1104).…”

“…[ 2 ] Moreover, the narrow direct band gap of Cu 2 O of 1.9-2.4 eV confers it with excellent light-harvesting ability. [ 16,17 ] The abundant surface functional groups and small fraction of sp 2 -hybridized C vests the prepared ND with a broad absorption spectrum and up-and down-conversion PL, resulting in good utilization of solar energy even in the near-infrared (NIR) region. In this contribution, we report that ND-embedded Cu 2 O nanocrystals (NDs-Cu 2 O) exhibit high photocatalytic HER performance and photostability.…”

Tunable direct band gap photoluminescent organic semiconducting nanoparticles from lignite

“…Studies have been reported on the synthesis of carbon-based dots from coal and humic substances which are rich in nanocarbon domain. These carbon-based materials are composed of organic compounds which are formed during the coalification or humification process 3 – 5 . Coal is being considered as an abundantly available precursor for the synthesis of nanotubes, nanoballs, carbon nanodots, onion-like fullerene and graphene quantum dots (GQDs).…”

“…Review of the literature reveals that the GQDs and carbon dots synthesized from lignite form a stable suspension with high colloidal stability 7 . Majority of the studies report the utilization of only the supernatant part of the sample and the residue part is discarded 3 , 4 , 9 . Whether these residuals can be converted to carbon dots with unique properties is worth investigating owing to the impact on the cost of production.…”