First Principle Study on the Z-Type Characteristic Modulation of GaN/g-C₃N₄ Heterojunction

This study investigates the stability, electronic structure, and optical properties of the GaN/g-C₃N₄ heterojunction using the plane wave super-soft pseudopotential method based on first principles. Additionally, an external electric field is employed to modulate the band structure and optical properties of GaN/g-C₃N₄. The computational results demonstrate that this heterojunction possesses a direct band gap and is classified as type II heterojunction, where the intrinsic electric field formed at the interface effectively suppresses carrier recombination. When the external electric field intensity (E) falls below -0.1 V/Å and includes -0.1 V/Å, or exceeds 0.2 V/Å, the heterojunction undergoes a transition from a type II structure to the superior Z-scheme, leading to a significant enhancement in the rate of separation of photogenerated carriers and an augmentation in its redox capability. Furthermore, the introduction of a positive electric field induces a redshift in the absorption spectrum, effectively broadening the light absorption range of the heterojunction. The aforementioned findings demonstrate that the optical properties of GaN/g-C₃N₄ can be precisely tuned by applying an external electric field, thereby facilitating its highly efficient utilization in the field of photocatalysis.