Structural Breathing of Graphite Oxide Pressurized in Basic and Acidic Solutions.

Graphite oxide immersed in excess of basic or acidic water media was studied using synchrotron X-ray diffraction at high pressure using diamond anvil cells. The lattice spacing of graphite oxide in excess of NaOH solution increases by the enormous value of 85% at 1.6 GPa. In contrast, structure expansion of graphite oxide immersed in liquid water with added HCl is significantly less pronounced compared with compression in pure water. Therefore, pressure-induced structural breathing of graphite oxide due to insertion/desertion of water into/from interlayer space is strongly enhanced in basic media and suppressed in acidic amounts of graphite oxide powder and solution. Strongly diluted samples with low relative amount of graphite oxide powder in the suspension exhibited less pronounced high-pressure anomaly.