Commonly used energy storage devices include stacked layers of active materials on two-dimensional sheets, and the limited specific surface area restricts the further development of energy storage. Three-dimensional (3D) structures with high specific surface areas would improve device performance. Herein, we present a novel procedure to fabricate macroscopic, high-quality, nitrogen-doped, 3D graphene/nanoparticle aerogels. The procedure includes vacuum filtration, freeze-drying, and plasma treatment, which can be further expanded for large-scale production of nitrogen-doped, graphene-based aerogels. The behavior of the supercapacitor is investigated using a typical nitrogen-doped graphene/Fe₃O₄nanoparticle 3D structure (NG/Fe₃O₄). Compared with 3D graphene/Fe₃O₄structures prepared by the traditional hydrothermal method, the NG/Fe₃O₄supercapacitor prepared by the present method has a 153% improvement in specific capacitance, and there is no obvious decrease in specific capacitance after 1000 cycles. The present work provides a new and facile method to produce large-scale, 3D, graphene-based materials with high specific capacitance for energy storage.

Herein, we present a simple and novel approach to fabricate a bifunctional compatible electrode, which has functionalities of photoelectric conversion and energy storage.