Reaction yields of diamondoid synthesis by plasmas generated in supercritical xenon

Abstract

Diamondoids are sp3 -hybridized carbon nanomaterials that hold promise for application in biotechnology, medicine, and opto-and nanoelectronics. While difficult or even impossible to realize by conventional organic synthesis methods, the synthesis of larger diamondoids was demonstrated by plasmas generated in supercritical fluids, however, the reaction mechanisms that lead to their formation are not clear. Here, we investigated the synthesis of diamondoids from adamantane and present a simple model that predicts the reaction rates of diamantane, triamantane, and tetramantane. The diamondoids were synthesized by micro dielectric barrier discharges arranged in arrays, generated at frequencies of 7 kHz and applied voltages of 5 − 10 kV p−p in supercritical xenon (pressure 5.56 − 8.22 MPa, temperature 290.0 − 310.2 K). The collected samples were analyzed and quantified by gas chromatography -mass spectrometry measurements. The reaction yields of diamantane increase with increasing precursor density and longer reaction times. Experimental data also suggests a stepwise reaction of higher diamondoids from lower diamondoids, and predicts lower reaction rates for higher diamondoids when compared to lower diamondoids.

Atmospheric pressure synthesis of diamondoids by plasmas generated inside a microfluidic reactor

“…Recent research on diamondoid synthesis from adamantane by electric microplasmas in supercritical xenon [27] suggests that diamondoid growth can come about in a step-wise fashion via the repeated addition of CH 3 radicals and H-abstraction. It was also suggested that the growth rate to larger diamondoids is limited by the availability of the next lower diamondoid [41].…”