Development of sheet-like dielectric barrier discharge microplasma generated in supercritical fluids and its application to the synthesis of carbon nanomaterials

A two-dimensional, sheet-like dielectric barrier discharge microplasma that can be generated in supercritical fluids was developed. With this type of plasma, generated in supercritical xenon, nanocrystalline diamonds and diamondoid-like sp3 bonded nano-hydrocarbons were synthesized by using adamantane as a precursor and seed. Pressure and temperature were set close to the critical point of xenon at 6.3 MPa and 290.2 K, respectively. The peak-to-peak voltage for microplasma generation was between 3.4 and 7.1 kV, at a frequency of 10 kHz and the power consumption of the microplasma determined from the I–V measurements reached about 30 mW. Transmission electron microscopy analysis of the lattice of the synthesized particles revealed crystal structures similar to those observed in nanodiamonds, while micro-Raman spectra yielded features also found in Raman and ab initio computational studies of diamondoids.