Insulating Electronic States Near the Dirac Point Arising from Twisted Stacking and Curvature in 3D Nanoporous Graphene

Abstract

Twist-stacked graphene with a twist angle $\hat{I}¸$ of $\sim 5^{\circ }$--$30^{\circ }$ retains two-dimensional monolayer graphene-like Dirac states near the Dirac point. In three-dimensional nanoporous graphene (3D-NPG), curvature inherently produces twist-stacking and topological defects required to form a porous network. When regions with $\hat{I}¸\ge 5^{\circ }$ dominate, Dirac states in individual layers are expected to persist, allowing the Dirac-electron behavior to be tuned through coupling to the 3D curved geometry. However, predicted band gap formation or localized states have remained unobserved. Here we report that 3D-NPG maintains monolayer-like Dirac electronic states while simultaneously exhibiting insulating behavior near the Dirac point. Raman G-band softening confirms these monolayer-like states, and an Arrhenius-type temperature-resistance trend coexisting with weak localization near the Dirac point indicates partially insulating states induced by topological defects. These findings demonstrate that 3D-NPG hosts distinctive Dirac electronic states coupled to 3D curvature, providing a platform for developing new functionalities in 3D graphene-based electronics and energy devices.

30 pages, 5 figures, and supplementary material. The final published version will appear in Carbon