Graphene

Already in the 19th century, scientists speculated that graphite was composed of layers.

An excerpt from the article 19 facts about graphene

This was only proven through research at the beginning of the 20th century, In 1947, the first theoretical description of graphene was created by Philip Russel Wallace. However, due to the two-dimensional nature of graphene, it was believed that this type of material could not function in nature.