Constructing a hierarchical graphene–carbon nanotube architecture for enhancing exposure of graphene and electrochemical activity of Pt nanoclusters

Stacking of individual graphene sheets (GS) is effectively inhibited by introducing one-dimensional carbon nanotubes to form a 3-D hierarchical structure which enhances the utilization of GS-based composites. From SEM images, CNTs are useful nanospacers for diminishing the face-to-face aggregation of GS. The specific electrochemically active surface area (SECSA) and specific double-layer capacitance (CS,DL) of Pt/GS–CNTs (127.9 m2/g, 171.3 F/g) is much higher than that of Pt/GS (105.4 m2/g, 104.7 F/g) and Pt/CNTs (51.5 m2/g, 37.1 F/g), revealing the synergistic effects between GS and CNTs on enhancing the electrochemical activity of Pt nanoparticles and electrolyte-accessible surface area.