Inter-molecular interaction in Polypyrrole/TiO2: A DFT study

Density functional theory study of Polypyrrole/TiO2 have been carried out at molecular level, to find its internal nature for the tuning of photocatalytic efficiency. Molecular isolated TiO2 interacts with various pyrrole oligomers for the investigation of inter-molecular interaction. A narrowing in band gap and better visible light absorption are achieved compared to their individual constituents, based on electronic properties simulations. Electrostatic potential, the density of states, IP, EA, UV-vis spectra and band gap are also supportive to the composite formation. Inter-molecular interaction energy (-28 to -45 kcal mol(-1)), counterpoised corrected (BSSE), and Delta EgCP-D3 methods are employed which confirm the existence of a strong covalent type of bonding between Py and TiO2 in nPy-TiO2 composites. Finally, Mulliken and natural bonding orbital analysis have pointed out that Py oligomers are p-type and donated electron cloud density to TiO2 in all of the nPy-TiO2 composites. (C) 2016 Elsevier B.V. All rights reserved.