Sheets of graphene-based material comprising single layer graphene and suitable for formation of a plurality of perforations in the single layer graphene are provided. In an aspect, the sheets of graphene-based material are formed by chemical vapor deposition followed by one or more conditioning steps. In a further aspect, the sheets of graphene-based material include non-graphenic carbon-based material and may be characterized the amount, mobility and/or volatility of the non-graphenic carbon-based material.