▎ 摘　　要

Herein, three-dimensional mesoporous graphene conductive networks supporting bimetallic PtAg alloyed nanoparticles (i.e. PtAg/3DMGS) with a superior composited nanostructure have been fabricated for advanced oxygen reduction reaction electrocatalysts. The unique architecture of 3D porous graphene exhibits a high surface area (1382 m(2) g(-1)), a well-defined mesoporous structure (an average pore size of 3.28 nm), as well as an excellent electronic conductivity (1350 S m(-1)). Inside the PtAg/3DMGS, high-density and ultrafine PtAg NPs (similar to 2.5 nm) were well dispersed on the porous surface of 3DMGS. The combination of ultrafine PtAg NPs and 3DMGS conductive networks provides a relatively stable macroporous composite architecture, which offers convenient binary channels for both electron transport and ion diffusion. This promising PtAg/3DMGS composite material reveals an ultrahigh mass activity (at 0.9 V) of 392 mA mg(Pt)(-1), which is nearly 4 times that of Pt/C (TKK) (102 mA mg(Pt)(-1)). After 1000 CV cycles, the retention rates of mass activity are 81.6% and 66.7% for PtAg/3DMGS and Pt/C (TKK), respectively. These results demonstrate that the PtAg/3DMGS composite material is a promising electrocatalyst with high catalytic activity and high stability for the oxygen reduction reaction.