▎ 摘　　要

NOVELTY - A sandwich structure electrocatalyst comprises graphene oxide as a carrier, and a metal complex grown in-situ to construct a sandwich structure. USE - Sandwich structure electrocatalyst is used in metal-air battery (claimed). ADVANTAGE - The reduction in electrochemical performance of the sandwich structure electrocatalyst caused by agglomeration of nanoparticles and limited porous channel in carbonization process of multiple metal complexes, is prevented. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the sandwich structure electrocatalyst, which involves preparing graphene oxide using graphite powder as a raw material, by improved Hummer method, adding graphene oxide and transition metal salt to a solvent, stirring, ultrasonically dispersing, obtaining a solution (A), dissolving nitrogen source in the solvent under heating, then adding solution (A), heating, stirring, cooling, washing, freeze-drying, and carbonizing dried product at high temperature in an inert gas atmosphere.