Hydrogen storage of a mechanically milled carbon material fabricated by plasma chemical vapor deposition

Carbon materials were prepared by plasma chemical vapor deposition at different pressures without catalyst, and the structure and hydrogen storage characteristics of milled and unmilled samples of the materials were evaluated. Using this approach, we were able to fabricate graphite microcrystals with a crystallite size of several nanometers, and the crystallite size and surface area could be controlled by changing the pressure during plasma chemical vapor deposition. The hydrogen storage capacity of the unmilled materials was 0.3 wt%, but milling increased this value to 1.0 wt% by reducing the crystallite size and increasing the crystallite surface area.