  The abundant bonding possibilities of Carbon stimulate the design of numerous
carbon allotropes, promising the foundation for exploring
structure-functionality relationships. Herein, utilizing the space bending
strategy, we successfully engineered a two-dimensional carbon allotrope with
pure sp2 hybridization, named "Wave-graphene" from the unique wave-like ripple
structure. The novel Wave-graphene exhibits full-auxetic behavior due to
anisotropic mechanical response, possessing both negative and zero Poisson's
ratios. The fundamental mechanism can be attributed to the fact that highly
buckled out-of-plane structures lead to anisotropic responses of in-plane
nonlinear interactions, which further lead to anisotropy of lattice vibrations.
In addition, Wave-graphene is found having quasi-direct wide bandgap of 2.01
eV, the excellent optical transparency and the high flexibility. The successful
design of Wave-graphene with excellent outstanding multifunctional properties
shows that the utilization of space bending strategies can provide more degrees
of freedom for designing novel materials, further enriching the carbon material
family and supplementing its versatility.
