Diamondoid synthesis in atmospheric pressure adamantane-argon-methane- hydrogen mixtures using a continuous flow plasma microreactor

Due to their small size, low-power consumption and potential for integration with other devices, microplasmas have been used increasingly for the synthesis of nanomaterials. Here, we have investigated the possibility of using dielectric barrier discharges generated in continuous flow glass microreactors for the synthesis of diamondoids, at temperatures of 300 and 320K, and applied voltages of 3.2-4.3kVp-p, at a frequency of 10kHz. The microplasmas were generated in gas mixtures containing argon, methane, hydrogen and adamantane, which was used as a precursor and seed. The plasmas were monitored by optical emission spectroscopy measurements and the synthesized products were characterized by gas chromatography - mass spectrometry (GC-MS). Depending on the gas composition, the optical emission spectra contained CH and C₂ bands of varying intensities. The GC-MS measurements revealed that diamantane can be synthesized by microplasmas generated at atmospheric pressure, and that the yields highly depend on the gas composition and the presence of carbon sources.