▎ 摘　　要

NOVELTY - Preparing graphene, comprises supplying a gas (including carbon dioxide, methane and water) on a metal catalyst, and reacting and cooling the resultant. USE - The method is useful for preparing graphene, which is used for manufacturing a semiconductor circuit, and in a graphene-encapsulated metal nanoparticle for light emitting material for a display, an electrode material of a battery or a solar cell, an in vivo drug delivery material (all claimed), sensors, and memories. ADVANTAGE - The method ensures that the graphene can be easily processed into a one- or two-dimensional nanopattern to adjust semiconductor-conductor properties, thus massively producing the graphene with large area, low cost and high reproducibility. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a graphene-encapsulated metal nanoparticle prepared by the above method; and (2) a hollow graphene nanoparticle prepared by removing the metal nanoparticle from the graphene-encapsulated metal nanoparticle.