Functional groups bridging the layers of nitrogen carbide nanosheets facilitate ultrafast interlayer charge transfer: ab initio nonadiabatic molecular dynamics simulations

Abstract

Two-dimensional (2D) layered nitrogen carbides (CN) are potential photocatalytic materials. However, their photocatalytic efficiency is severely constrained by the inefficient transfer and separation of the carriers, especially between layers. Herein, based on hybrid density functional theory and ab initio nonadiabatic molecular dynamics, we find the formation of interlayer type II band alignments in few-layer graphitic C₃N₄ (g-C₃N₄) through bridging functional groups (–NH₂, –COOH, and –OH), thus promoting the interlayer separation of photogenerated carriers. Specifically, functional groups facilitate the photogenerated carriers to overcome the Coulomb interaction in-plane and transfer between layers, benefiting from the disruption of symmetry and the formation of interlayer carrier transfer channels. Notably, the photoexcited carriers achieve ultrafast interlayer transfer on the fs timescale due to the strong nonadiabatic coupling of the interface transfer channel, suppressing the recombination of carriers with a timescale exceeding 10 ns. Furthermore, the hydrogen evolution reaction activity at the N site is enhanced due to the increased concentration of electrons, as indicated by the change in Gibbs free energy values ranging from −0.01 eV to 0.10 eV. Our work provides a feasible strategy to transfer interlayer carriers in layered 2D materials.