Flame-synthesized carbon nanoparticles of varying sizes were produced in premixed stretch-stabilized stagnation ethylene-oxygen-nitrogen flames under various sooting conditions. The experimental setup consists of a burner with an aerodynamically-shaped nozzle, a stagnation surface/sampling probe assembly, and a scanning mobility particle sizer. The pseudo-one-dimensional formulation was invoked to simplify the stagnation flow field. A modified version of the OPPDIF code was used to compute the gas-phase species, temperature, and velocity profiles using USC Mech II as the reaction kinetics model, which consists of 111 species and 784 reactions. Thermophoretic velocities and particle residence times were calculated for each flame configuration. Soot volume fractions and particle size distribution functions were measured in a series of five atmospheric pressure ethylene-oxygen-nitrogen flames with maximum temperatures ranging from 1969 to 2132 K. The UV–Visible absorption spectral analysis was conducted in the 190–1400 nm range for the flame-synthesized nanoparticles to evaluate the optical bandgap from their resulting Tauc spectra. The results from the present study suggest a strong dependence of the optical bandgap on particle size. It is shown that quantum confinement effects, which arise due to the finite size of the particles, play an essential role in determining the final absolute value of the optical bandgap. In the present study, flame-synthesized carbon nanoparticles (CNPs) are found to exhibit quantum confinement behaviors.
Combustion Synthesis of Functional Nanoparticles
Lect.Notes Mechanical Engineering
2022-07-24
25 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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