First-Principles Calculations of Exciton Radiative Lifetimes in Monolayer Graphitic Carbon Nitride Nanosheets: Implications for Photocatalysis

In this work, we report on the exciton radiative lifetimes of graphitic carbon nitride monolayers in triazine-based (gC3N4-t) and heptazine-based (gC3N4-h) forms, as obtained by means ground-state plus excited-state ab initio calculations. By analyzing fine structure, highlight presence dark states show that photogenerated electron–hole (e-h) pairs gC3N4-h are remarkably long-lived, with an effective lifetime 260 ns. This fosters employment photocatalysis makes it attractive for emerging field devices. Although very long intrinsic important prerequisite several applications, pristine nanosheets low quantum photoconversion efficiency, mainly due to lack efficient e-h separation mechanism. We then focus a vertical heterostructure made gC3N4-t layers, which shows type-II band alignment looks promising achieving net charge separation.