▎ 摘　　要

NOVELTY - A metal catalyst is oxidized by reacting (S2) laminate of graphene and catalyst metal with an oxide liquid. Thus, detection (S3) of grain boundary of graphene is enabled. USE - Method for detecting grain boundary of graphene (claimed). ADVANTAGE - The method enables easy detection of grain boundary of graphene having maximum area. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for grain boundary device, which comprises a reactive portion which enables reaction of laminate of graphene and catalyst metal with oxide liquid and oxidizes the catalyst metal. DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart explaining detection of grain boundary of graphene. Preparation of metal catalyst and graphene laminate (S1) Reaction of laminate with oxide liquid (S2) Detection of crystal grain boundaries (S3) Determination of state of graphene (S4)