Impact of N₂ admixture on the synthesis of graphitic carbon nanoparticles using atmospheric-pressure microwave plasma

Abstract

Atmospheric-pressure microwave plasma was utilized for catalyst-free gas-phase synthesis of graphitic carbon nanoparticles by adding CH4 to a mixture of N2 and He. The impact of N2 on the formation of the graphitic carbon nanoparticles was analyzed by increasing the N2 flow rate from 0 to 20 slpm and decreasing the He flow rate from 40 to 20 slpm simultaneously. The addition of N2 altered the morphology of the carbon nanoparticles to obtain flatter and larger shapes. Furthermore, carbon nanoparticles synthesized with N2 possessed more graphitic structures with higher C/O ratios and larger crystallite sizes than those synthesized without N2. The analysis of gas compositions at thermodynamic equilibrium states demonstrated that CN and HCN were the dominant precursor species when N2 was added. The presence of N atoms or N-containing species seem to have a synergistic effect combined with H atoms on the formation of the graphitic carbon nanoparticles.

A double‐mode planar argon plume produced by varying the distance from an atmospheric pressure plasma jet

“…Without the need for a vacuum chamber, atmospheric pressure non-equilibrium plasmas are very attractive for applications [1], such as ozone generation [2], methane conversion [3], material synthesis [4], surface modification [5], water treatment [6], and plasma medicine [7,8] etc.…”

Machine learning-based prediction of operation conditions from plasma plume images of atmospheric-pressure plasma reactors

“…These advantages enable a more uniform treatment of the process gases and longer operation times without electrode replacement necessitated by electrode erosion. In addition to the decomposition of PFCs and VOCs, atmospheric-pressure microwave plasmas have been applied successfully to the dry reforming of hydrocarbons [21,22], synthesis of nanomaterials [23], and nitrogen fixation [24]. Under atmospheric pressure, the gas temperature at the plasma core attained approximately 6000 K when produced in molecular gases, which was sufficiently high to break most of the chemical bonds [20][21][22]25].…”