LAUSR

Abstract Single atoms of platinum (Pt), palladium (Pd) or gold (Au) trapped by two-dimensional graphitic carbon nitride (g-C 3 N 4 ) exhibit superior photocatalytic performance. However, the underlying mechanism of single-atom noble metal/g-C 3 N 4 photocatalytic system is still unclear. Herein, the structural, electronic and optical properties of single-atom Pt, Pd and Au loaded on bilayer g-C 3 N 4 (BL-g-C 3 N 4 ) substrate were investigated by density functional theory (DFT) simulations. The results indicate that single-atom Pt/Pd/Au loading can significantly narrow the band gap of g-C 3 N 4 and thus increase its light absorption in the visible-light region. Rather than being adsorbed on the surface, Pt and Pd atoms tend to be embedded into g-C 3 N 4 interlayer and act as bridges to facilitate the interlayer charge carrier transfer due to the effects of conduction band offset. In particular, an internal electric field is generated in Pt/BL-g-C 3 N 4 , which is further beneficial for separating charge carrier of photoexcited g-C 3 N 4 . By contrast, Au can only be adsorbed on the g-C 3 N 4 surface (in the six-fold cavity) and deliver a limited amount of charge carrier excited in the N-conjugated aromatic pore of g-C 3 N 4 surface. Our finding is conducive to understanding the interactive relationship between single-atom noble metal co-catalysts and g-C 3 N 4 and to the design of high-efficiency photocatalyst.