▎ 摘　　要

Here we demonstrate for the first time a water-based surfactant-free synthesis of three-dimensional porous Pd@Pt core-shell nanoflowers on graphene. The obtained Pd@Pt-graphene hybrids exhibited substantially enhanced electrocatalytic activity and stability relative to the commercial Pt/C catalyst originating from this exquisite nanoarchitecture for three-dimensional molecular accessibility and graphene-metal interaction.