Three-dimensional (3D) architectures of graphene are of interest in applications in electronics, catalysis devices, and sensors. However, it is still a challenge to fabricate macroscopic all-graphene 3D architectures under mild conditions. Here, a simple method for the preparation of 3D architectures of graphene is developed via the in situself-assembly of graphene prepared by mild chemical reduction at 95 °C under atmospheric pressure without stirring. No chemical or physical cross-linkers or high pressures are required. The reducing agents include NaHSO₃, Na₂S, Vitamin C, HI, and hydroquinone. Both graphene hydrogels and aerogels can be prepared by this method, and the shapes of the 3D architectures can be controlled by changing the type of reactor. The 3D architectures of graphene have low densities, high mechanical properties, thermal stability, high electrical conductivity, and high specific capacitance, which make them candidates for potential applications in supercapacitors, hydrogen storage and as supports for catalysts.

It is still a challenge to prepare graphene from graphene oxide (GO) under a mild thermal reduction. Here we report that GO can even be reduced at a low temperature (below 150 °C) at atmospheric pressure in a mixture of N,N-dimethylacetamide (DMAc) and water (10 : 3, v/v) under the protection of nitrogen gas. FT-IR, XRD, XPS, Raman, and AFM studies confirmed the thermal reduction of GO and the formation of graphene. The as-prepared graphene can be fully dispersed in pure DMAc to form an organic suspension, and the suspension is stable for at least two months at room temperature.