A 12-cm-diameter tubular reactor was implemented to fabricate a large-area PG (Figure , experimental setup shown in Figure ). This reactor could house an 11 cm wide and 55 cm long graphene coupon. The reactor was connected to an O3 generator, yielding 8% O3 in O2. An evacuation and gas delivery system was designed to rapidly exchange the gas environment (argon (Ar), hydrogen (H2), O3) and to attain control over the reaction time. Several critical steps were identified and implemented in sequence. These are the removal of atmospheric contaminations on graphene, oxidation of graphene, gasification for pore generation, and finally, reduction of CuO formed during the O3 exposure step. The corresponding conditions are detailed in Figure .