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3D nitrogen-doped graphene aerogel nanomeshes (N-GANMs) with hierarchical porous structures were facilely synthesized from graphene oxide and urea using iron nitrate as the etching agent. The resulting materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 adsorption–desorption. The supercapacitor performance was characterized by cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy, respectively. Compared with the bare graphene aerogel (GA), N-GANMs showed higher specific surface area, more abundant meso-macroporous pores, and much better electrochemical properties. The specific capacitance of N-GANMs was as high as 345.8 F g−1, which was much higher than that of GA and most of the reported carbon-based materials, and the value remains at about 321.0 F g−1 over 2000 cycles at 1.0 A g−1 in 2.0 M KOH. In addition, the N-GANMs demonstrated a high energy density of 20.82 W h kg−1 at a power density of 449.97 W kg−1 and their cycle performance remained approximately 100% after 10 000 cycles at 5.0 A g−1 in 1.0 M Na2SO4. The excellent behaviors might have originated from their hierarchical porous structures and the incorporation of nitrogen. [ABSTRACT FROM AUTHOR]