Significantly Enhanced Charge Separation in Rippled Monolayer Graphitic C 3 N 4

Graphitic C 3 N 4 (g−C 3 N 4 ) is one of the most popular two‐dimensional (2D) materials as a milestone of metal‐free photocatalysis for solar water splitting. However, pure g−C 3 N 4 presents a poor efficiency of electron‐hole separation. Here by first‐principles calculations, we propose that without any chemical modification, the electron‐hole separation can be significantly promoted by just rippling g−C 3 N 4 . Interestingly, the rippled structures are found more stable than complanate structure in thermodynamics. Furthermore, a lateral Type‐II heterojunction is formed in rippled g−C 3 N 4 between the strongly and hardly rippled areas, with the valence band maximum (VBM) and conduction band minimum (CBM) of the whole structure spatially separated. Thus the photo‐generated electrons and holes are driven to different regions in rippled monolayer g−C 3 N 4 . Our work reveals the rippled g−C 3 N 4 , with potential advantage of high efficiency of electron‐hole separation, is a flexible and promising platform for metal‐free photocatalytic water splitting.