▎ 摘　　要

Nacre-like graphene films are prepared by evaporation-induced assembly of graphene oxide dispersions containing small amounts of cellulose nanocrystal (CNC), followed by chemical reduction with hydroiodic acid. CNC induces the formation of wrinkles on graphene sheets, greatly enhancing the mechanical properties of the resultant graphene films. The graphene films deliver an ultrahigh tensile strength of 765 +/- 43 MPa (up to 800 MPa in some cases), a large failure strain of 6.22 +/- 0.19%, and a superior toughness of 15.64 +/- 2.20 MJ m(-3), as well as a high electrical conductivity of 1105 +/- 17 S cm(-1). They have a great potential for applications in flexible electronics because of their combined excellent mechanical and electrical properties.