In-situ observation of structural change in MWCNTs under high-pressure H2 gas atmosphere

Multi-walled carbon nanotubes having a tube-opened framework (o-MWCNTs) have been pressurized in an atmosphere of hydrogen up to 2.5 GPa and at room temperature using a diamond-anvil cell (DAC). Compression up to 0.57 GPa was accompanied by expansion of the honeycom-lattice structure of graphene sheets in spite of decreasing interlayer distance. A deviation in the in-plane C–C distance was obtained to be 3.8 × 10− 4 nm at 0.57 GPa. The expansion in the honeycom-lattice structure suggests generation of charge-transfer interaction between graphite and hydrogen. This is one of the proofs that hydrogen is intercalated in the interlayer space of o-MWCNTs.