Highly conductive and flexible mesoporous graphitic films prepared by graphitizing the composites of graphene oxide and nanodiamond

Flexible mesoporous graphitic films with high conductivities were prepared by graphitizing the composite films of graphene oxide (GO) and nanodiamond (ND). After graphitization, ND was changed into onion-like carbon (OC) and GO was reduced to conductive graphene. In the graphitic films, OC nanoparticles were sandwiched between thermally reduced graphene oxide (or graphene) sheets, which not only prevented the aggregation of graphene sheets, but also formed mesopores. The maximum specific surface area of the porous graphitic films was measured to be around 420 m(2) g(-1) and the diameters of their pores were mostly in the range of 2-11 nm. Furthermore, they are highly conductive with conductivities in the range of 7 400 to 20 300 S m(-1). These films are flexible and can be mechanically shaped into the desired structures. Thus, they can be directly used as the electrodes of supercapacitors without the addition of a polymer binder or a conductive additive. The supercapacitors showed a long cycling life and their specific capacitance was optimized to be 143 F g(-1) at a discharge rate of 0.2 A g(-1).