Characterization of nanoscale detonation carbon produced in a pulse gas-detonation device

Nanoscale Detonation Carbon (NDC) was produced in a Pulse Gas-Detonation Device (PGDD) by detonation of C₂H₂ + kO₂ mixtures, with variation of k from 0.11 to 0.82. The obtained NDC was characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffractometry (XRD), Raman Spectroscopy (RS), and X-Ray Photoelectron Spectroscopy (XPS). It was shown that the morphology and structure of the carbon particles change significantly with increase of the oxygen to carbon molar ratio. As oxygen content increases (k increases from 0.11 to 0.51), hollow rounded carbon particles grow in size reaching 200 nm in diameter. At oxygen content above some critical value (k is >0.60), the particles acquire a shape of graphene-like flakes with a thickness of up to 20 nm. The degree of graphitization of NDC increases rapidly with the growth of oxygen to carbon molar ratio up to k = 0.51. With a further increase in k, the growth rate of the degree of graphitization slows down. It was also found that graphitization of NDC is affected by the length of the barrel of a PGDD, the addition of argon to the acetylene-oxygen mixture, and the nature of the purge gas (nitrogen or argon). The XPS analysis revealed the presence of adsorbed water, as well as hydroxyl and carbonate groups on the surface of NDC particles. With an increase in k from 0.11 to 0.68, the specific surface area of NDC S_BET decreases from 230 to 107 m²/g.