Ultrafast shock synthesis of nanocarbon from a liquid precursor

Abstract

Carbon nanoallotropes are important nanomaterials with unusual properties and promising applications. High pressure synthesis has the potential to open new avenues for controlling and designing their physical and chemical characteristics for a broad range of uses but it remains little understood due to persistent conceptual and experimental challenges, in addition to fundamental physics and chemistry questions that are still unresolved after many decades. Here we demonstrate sub-nanosecond nanocarbon synthesis through the application of laser-induced shock-waves to a prototypical organic carbon-rich liquid precursorliquid carbon monoxide. Overlapping large-scale molecular dynamics simulations capture the atomistic details of the nanoparticles' formation and evolution in a reactive environment and identify classical evaporation-condensation as the mechanism governing their growth on these time scales.

Using DFTB to Model Photocatalytic Anatase–Rutile TiO2 Nanocrystalline Interfaces and Their Band Alignment

“…Specifically, the two-body interactions are expressed as a linear combination of Chebyshev polynomials of the first kind In this case, T n ( s ij ) is the Chebyshev polynomial of the first kind of n th order, e i and e j are the element types of atoms i and j , and s ij is a transformation of the interatomic distance r ij over the Chebyshev interval of [−1,1] using a Morse-like function. In addition, Θ 2 corresponds to the two-body polynomial order, f C ij ( r ij ) is the cutoff function that ensures the potential and its derivative vary smoothly to zero beyond a specified distance, and f P ij ( r ij ) is a penalty function 13 , 17 that helps to prevent sampling of interatomic distances below those seen in the training set (see ref ( 18 ) for further details). is a set of permutationally invariant coefficients of linear combination for a given atom pair type that are determined via a linear least-squares method.…”

Calculation of the Detonation State of HN3 with Quantum Accuracy

“…Nevertheless, DFT-MD simulations scale poorly with the number of valence electrons and consequently are usually limited to picosecond time scales and nanometer system sizes. In contrast, many experimental reactions can occur over length-and time-scales which are orders of magnitude larger [9][10][11] and longer 6,12,13 than the ones that can be achieved by DFT-MD simulations, and thus make this method ill-suited for many high pressure studies. In particular, the reaction zone time of many common detonating explosives is 10-100 ns, while the reaction zone length is in the 60-800 nm range 14 .…”

Chemistry-Mediated Ostwald Ripening in Carbon-Rich C/O Systems at Extreme Conditions

“…[1][2][3][4] Many of these "next-generation" nanomaterials, which include nanodiamonds, nanographite, amorphous nanocarbon, nano-onions etc., are currently being studied for possible applications spanning quantum computing to bio-imaging, 1 and ongoing research suggests that high-pressure synthesis could lead to the discovery and possibly the tailored design of many more. Both laserdriven shock 5,6 and detonation experiments 3,7,8 can be used to drive carbon-rich materials to the 1000s of K and 10s of GPa conditions under which complex processes lead to the formation of 2-10 nm nanocarbons within 100s of nanoseconds. However, the precise chemical and physical phenomena governing nanocarbon formation under elevated pressure and temperature largely remain terra incognita, due in part to the formidable challenges associated with studying systems at such extreme states.…”

“…In this paper we significantly advance the modeling effort initiated in ref. 6 by performing an in-depth investigation of carbon condensation (precipitation) in oxygen deficient C/O mixtures at high pressures and temperatures. To this end, we leveraged the ChIMES framework to both substantially extend the simulations of Ref.…”

“…To this end, we leveraged the ChIMES framework to both substantially extend the simulations of Ref. 6 and perform new simulations at different C/O ratios. C/O systems are often employed in practical applications and are excellent candidates for uncovering the essential features of this complex process due to their relative simplicity.…”