Three-dimensional hybrid aerogels built from graphene and polypyrrole-derived nitrogen-doped carbon nanotubes as a high-efficiency Pt-based catalyst support

The three-dimensional (3D) hybrid aerogels built from graphene and polypyrrole-derived nitrogen-doped carbon nanotubes (G-NCNTs) are synthesized by facile hydrothermal and heat treatment process using graphite oxide (GO) and polypyrrole nanotubes (PNTs) as precursors. The 3D G-NCNTs hybrid aerogels, in which the NCNTs are dispersed homogeneously in the graphene sheets, are designed to efficiently support Pt nanoparticles. Comparing with 3D graphene (GA), the 3D G-NCNTs supported Pt-based catalyst possesses improved electrocatalysis activity and stability toward methanol oxidation reaction (MOR). The mass activity of Pt/G-NCNTs-1/2 catalyst is 0.74 A mg⁻¹_Pt, which is 1.4 times that of the Pt/GA catalyst (0.54 A mg⁻¹_Pt). In addition, the retention rate after 1000 cycles for Pt/G-NCNTs-1/2 catalyst is as high as 82.4%, obviously superior to 68.5% of Pt/GA catalyst. The enhanced electrochemical performance is ascribed to the synergistic effect of GA and NCNTs. The introduction of NCNTs can uniformly disperse and strongly anchor Pt nanoparticles due to the increase in nitrogen active sites. Moreover, the NCNTs introduced into GA may prevent the restacking of graphene sheets, and provide a large accessible surface area for better dispersing Pt nanoparticles and transporting reactants and products.