Rationally designed 2D/2D SiC/g-C3N4 photocatalysts for hydrogen production

Abstract

Visible-light driven photocatalytic hydrogen production from water is a hotspot in renewable energy. Recent experiments have proved that 2D/2D SiC/g-C₃N₄ heterojunctions exhibit greatly improved photocatalytic activities; still lacking is a fundamental understanding of the complex mechanism as well as rationally designed schemes for highly-effective SiC/g-C₃N₄ photocatalysts. Using state-of-the-art hybrid density functional theory, we uncover as many as 7 advantageous factors in SiC/g-C₃N₄ layered photocatalysts: (1) severe bending of g-C₃N₄, (2) formation of type-II heterojunctions, (3) ideal bandgap widths around 2.0 eV, (4) intimate interface contact and strong interfacial interactions, (5) considerable built-in electric field, (6) suitable band edge positions, and (7) near-zero Gibbs free-energy (ΔG_H*). This theoretical work not only offers a comprehensive insight into the enhanced photocatalytic mechanism for 2D/2D SiC/g-C₃N₄ heterojunctions, but also provides rational strategies for designing highly-effective SiC/g-C₃N₄ photocatalysts in producing hydrogen.