Direct Atomic‐Scale Structure and Electric Field Imaging of Triazine‐Based Crystalline Carbon Nitride

Crystalline carbon nitrides (CNs) have recently attracted considerable attention owing to their superior photocatalytic activity. However, the electron-beam-sensitive nature of crystalline CNs hinders atomic-resolution imaging of their local structures by conventional (scanning) transmission electron microscopy ((S)TEM) techniques. Here, the atomic structure of a triazine-based crystalline CN, poly(triazine imide) (PTI) incorporated with lithium and chloride ions, is unambiguously revealed using the emerging imaging technique of differential phase contrast STEM under a low dose. The lightest-element Li/H configuration is resolved within framework cavities of PTI and significantly affects the electronic structure for photoabsorption. The atomic electric field of PTI crystal directly determined in real space provides a fundamental evidence for the chemical bonding of Li ions and adjacent atoms for the migration of photogenerated carriers. These results facilitate the comprehension on local atomic configuration and chemical bonding state of crystalline CNs and can lead to a deeper understanding of the photocatalytic mechanism.