▎ 摘　　要

Converting natural graphite to high-performance graphene films is very attractive due to graphite's abundance. However, this conversion is challenging to do inexpensively and under ambient conditions. One of the major challenges is how to design the interface between adjacent graphene nanosheets to integrate high strength, high toughness, and high conductivity into graphene films. Here, we demonstrate that a long-chain pi-pi bonding agent can bridge reduced graphene oxide nanosheets into ultrastrong, supertough, and highly conductive graphene films. The strain dependence of Raman frequency shift and molecular dynamics simulations together reveal the strengthening and toughening mechanisms. Additionally, the long-chain pi-bridging induces substantial improvement in the graphene nanosheet alignment. The tensile strength and toughness are 1,054 MPa and 36 MJ/m(3), surpassing those of reported graphene films. Meanwhile, the electrical conductivity reaches 1,192 S/cm, comparable with high-temperature annealed graphene films. The bioinspired strategy opens an avenue for the assembly of nanoscale building blocks into high-performance films.