A DFT study of polyaniline/ZnO nanocomposite as a photocatalyst for the reduction of methylene blue dye

Water pollution is a major environmental concern since many water sources are being contaminated with pollutants that are not easily degraded. Photocatalysis is an attractive process which is capable of degrading pollutants in aquatic environments. Nanomaterials function as efficient photocatalytic materials. ZnO is a nanomaterial which is a widely used semiconductor photocatalyst. In this study, density functional theory (DFT) with the B3LYP functional and 6-311G (d,p) basis set was used to examine the binding of a methylene blue (MB) dye molecule onto the surface of polyaniline (PANI)/(ZnO)(n) (n = 7-12) nanocomposite. The dye molecule was adsorbed at two different positions on the PANI/(ZnO)(n) nanocomposite. The binding energies of the PANI/(ZnO)n MB complexes was calculated and indicated a strong interaction at position 1. Natural bond orbital (NBO) analysis revealed effective charge transfer within the complexes which explained the mechanism and efficiency of the photocatalytic activity of these nanocomposites. Electrostatic potential (ESP), density of states and partial density of states supported the strong interaction of MB with the nanocomposite leading to the degradation of the dye molecule. (C) 2019 Elsevier B.V. All rights reserved.