Mechanically tough large-area hierarchical porous graphene films are fabricated by blade-casting of graphene oxide hydrogel and postcasting reduction. The as-prepared graphene films, which consist of well-exfoliated graphene nanosheets, possess interpenetrating 3D hierarchical porous structures, high strength and modulus, large specific area, and high electrical conductivity. Flexible film supercapacitors fabricated with the graphene electrodes show superior areal capacitance, good rate performance, and excellent mechanical stability.

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Reduced graphene oxide (RGO) diffraction gratings on glass substrates were fabricated by duplication of photoinduced surface-relief-gratings (SRGs) on azo polymer films through soft-lithographic methods. In the process, SRGs were inscribed on solid films of an epoxy-based azo polymer (BP-AZ-CA) by irradiation with interfering Ar + laser beams, which were used as grating masters. Polydimethylsiloxane (PDMS) stamps with duplicated surface gratings were obtained by replica mold against the masters. Finally, by using the PDMS stamps and RGO dispersions as "ink", the RGO diffraction gratings were fabricated through microcontact printing. The surface profiles and morphology of as-prepared RGO gratings were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The periods of replicated RGO gratings were the same as those of the masters. Meanwhile, the amplitudes of the printed RGO gratings were determined by the "ink" concentration and grating parameters of the PDMS stamps. By adjusting the preparation conditions, a series of RGO gratings with different periods and amplitudes were successfully fabricated. The optical properties of RGO gratings were characterized by diffraction efficiency measurements. The gratings showed typical thin grating characteristics with the diffraction efficiency (DE) of 7% for the green light. This new approach for preparing graphene gratings can provide a feasible way to explore the unique optical characteristics of RGO for developing graphene-based optical devices.Diffraction gratings made of reduced graphene oxide were fabricated by duplication of photoinduced azo polymer surface-relief-gratings through soft-lithography.