Low-energy 3D sp2 carbons with versatile properties beyond graphite and graphene
Carbon materials with full sp2-hybridized bonding, e.g. zero-dimensional (0D) fullerenes, 1D carbon nanotubes, and 2D graphene, possess outstanding and unparalleled properties, and have unique scientific and technological importance. The theoretical design and experimental exploration of other types of novel sp2 carbon allotropes, especially with 3D architectures, is always a compelling scientific theme. Here we proposed a class of low-energy 3D sp2 carbons with exceptional properties, not only possessing excellent mechanical properties such as high 3D strength, rubber-like ultra-stretchability, and negative Poisson's ratio, but also including the electronic properties of graphite-like metallicity and graphene-like Dirac cone, which are the desirable properties across a broad range of potential applications. Furthermore, a design route was suggested to access these 3D sp2 carbons by the polymerization of edge-functionalized graphene nanoribbon arrays.