Observing high-pressure chemistry in graphene bubbles

Abstract

Using IR spectroscopy, high-pressure reactions of molecules were observed in liquids entrapped by graphene nanobubbles formed at the graphene-diamond interface. Nanobubbles formed on graphene as a result of thermally induced bonding of its edges with diamond are highly impermeable, thus providing a good sealing of solvents within. Owing to the optical transparency of graphene and diamond, high-pressure chemical reactions within the bubbles can be probed with vibrational spectroscopy. By monitoring the conformational changes of pressure-sensitive molecules, the pressure within the nanobubble can be calibrated as a function of temperature and it is about 1 GPa at 600 K. The polymerization of buckministerfullerene (C60), which is symmetrically forbidden under ambient conditions, is observed to proceed in well-defined stages in the pressurized nanobubbles. Graphene anvil: Graphene bubbles can be used as a bench-top anvil cell for studying high-pressure chemistry. Pressure-sensitive molecules that undergo conformational changes were used to probe the internal pressures inside the bubbles, which are 0.5-1 GPa over a temperature window of up to 673 K. The pressure-induced oligomerization of C60 molecules occurring at distinct P-T windows could be followed using FTIR spectroscopy. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.