▎ 摘　　要

NOVELTY - Preparing layered graphene comprises e.g. (i) introducing graphite powder in the high pressure kettle and sealing; (ii) heating the high pressure kettle at 40-80 degrees C, injecting carbon dioxide through injection pump into high pressure kettle and maintaining 8-16 MPa pressure in the high pressure kettle, maintaining temperature and carbon dioxide pressure at supercritical state, opening the high pressure kettle ultrasonic probe and stirring device, stripping ultrasonic graphite under the supercritical state for 30-120 minutes in the high pressure kettle through micro-jet stripping device. USE - The method is useful for preparing layered graphene (claimed). ADVANTAGE - The method produces high quality graphene with less than or equal to 3 layers of graphene for 88-94%, monolayer graphene is more than 40%. The method is environmental-friendly and simple in process. DETAILED DESCRIPTION - Preparing layered graphene comprises (i) introducing graphite powder in the high pressure kettle and sealing; (ii) heating the high pressure kettle at 40-80 degrees C, injecting carbon dioxide through injection pump into high pressure kettle and maintaining 8-16 MPa pressure in the high pressure kettle, maintaining temperature and carbon dioxide pressure at supercritical state, opening the high pressure kettle ultrasonic probe and stirring device, stripping ultrasonic graphite under the supercritical state for 30-120 minutes; and (iii) stripping ultrasonic materials in the high pressure kettle through micro-jet stripping device at normal pressure receiving tank for rapid decompression to obtain graphene product, micro-jet spraying stripping device comprises entrance, outlet and shrinking space and orderly connected between the entrance and exit of a throat section and a diffusion space, shrinking section gradually reduced from the inlet to the throat diameter, the diffusion space from the throat to the outlet direction is gradually enlarged, diameter ratio of the throat and the inlet is 0.15-0.3: 1 and the entrance and exit aperture are the same, introducing the material in the high-pressure state into the micro-jet stripping device and stripping off.