▎ 摘　　要

NOVELTY - Preparation of ultra-clean graphene involves using chemical vapor deposition, and providing foam copper above growth substrate. USE - Preparation of ultra-clean graphene (claimed). ADVANTAGE - The method introduces foam copper to obtain ultra-clean micron-grade graphene with continuous and large area, reduces amorphous adsorbate introduced during growth process, and is suitable for large-scale industrial production. The method produces sub-centimeter-level single crystal graphene (single domain region) which can be spliced into a single layer graphene film after further growth. The area of the single layer graphene film sample is only related to the size of copper foil. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for method for quickly assessing cleanliness of large areas of graphene, which involves depositing nanoparticles on the graphene sample, and evaluating cleanliness of the graphene sample according to the deposition of the nanoparticles.