▎ 摘　　要

Galvanic replacement reaction has been widely concerned, where a variety of materials can be nanostructured in different shapes. The galvanic replacement of gallium-based liquid metals (LMs) can be remarkably valued, because the highly dynamic and homogeneous film of LMs can offer more active metal atoms for the reaction. Nevertheless, the galvanic replacement mechanism of the gallium-based LM nanodroplets is still unrevealed entirely. To overcome this challenge, 2D graphene material (reduced graphene oxide, RGO) is employed to stabilize the liquid metal droplets and restrain the formation of oxide layer for the first time (LM@RGO). Two types of galvanic replacement patterns (intracellular and extracellular replacements) are revealed, which depend on the Gibbs free energy of redox reaction. The extracellular replacement pattern is adopted to produce the noble nanoparticles and the multilayered nanoparticles. In the intracellular replacement pattern, the galvanic replacement is not limited on the surface of LM@RGO. Owing to the internal alloying, LM@RGO with the superior electrochemical detection sensitivity is utilized to detect heavy metal ions. LM@RGO shows great potential in the application of preparing noble metal nanoparticles, the formation of composite nanoparticles with delicate structure and electrochemical detection of heavy metal ions.