Effect of acids on optical and dielectric properties of g-C3N4 and the DFT simulation

The two-dimensional (2D) graphitic carbon nitride currently has attracted attention for his electronic structure and optical properties. It is a good candidate for photocatalytic applications. The graphitic carbon nitride has been successfully synthesis and characterized by XRD, FTIR and UV-Vis Spectroscopy. The influence of acids treatment on structural and optical properties of g-C3N4 has been examined. It was found that the treatment of g-C3N4 bulk by different acids shows a disorder in the structure of samples which affect the optical performance of material. For the determination of the contributions of each orbital to the valence band maximum and the minimum conduction band the electronic structure of g-C3N4 has been investigated by density functional theory. The theoretical investigation reveals that the lone pair state and the pi bonding play an important role in the electronic structure of graphitic carbon nitride and favorites the absorption of the g-C3N4 in the visible light. The optical properties such as the extinction coefficient (k), the refractive index (n), the optical conductivity (sigma(opt)), and the dielectric function (epsilon(r), epsilon(i)) have been explored by DFT calculation and confirmed by the experimental results.