Sonochemical-assisted synthesis of 3D graphene/nanoparticle foams and their application in supercapacitor

Graphene and its derivatives have attracted much attention in application of electrochemical devices. Construction of three-dimensional (3D) heterostructured composites is promising for establishing high-performance devices, which enables large surface area, facilitated ion and electron transport, and synergistic effects between multicomponents. Here, we report a simple and general sonochemical-assisted synthesis to prepare various 3D porous graphene/nanoparticle (i.e., Pt, Au, Pd, Ru, and MnO2) foams using colloidal template. The 3D porous network structure of composite foams significantly improves a large surface area of around 550 m2 g–1 compared to the bare graphene (215 m2 g–1). This unique structure of 3D graphene/MnO2 enables further improvement of electrochemical characteristics, compared with bare graphene/MnO2 composite, showing a high specific capacitance of 421 F g–1 at 0.1 A g–1, high rate capability (97% retention at 20 A g–1), and good cycling performance (97% retention over 1000 cycles). Moreover, electrochemical impedance analysis demonstrates that electron and ion transfer are triggered by 3D porous structure.