A periodic density functional theory study of tetrazole adsorption on anatase surfaces: potential application of tetrazole rings in dye-sensitized solar cells.

A density functional theory (DFT) method (periodic DMol(3)) with full geometry optimization was used to study the adsorption of tautomeric forms of tetrazole on anatase TiO2 (101), (100), and (001) surfaces. It was found that the adsorption of tetrazole on the TiO2 surfaces does not proceed via a dissociative process, and negative shifts in the Fermi level of TiO2 were noted upon N-containing heterocycle adsorption. The configuration of the tetrazole during adsorption and the corresponding adsorption energies on different surfaces and sites were estimated. In addition, it was found that tetrazole may be adsorbed on TiO2 surfaces through an interaction between a cation on the surface and a lone pair on the N1 or N2 atom of the tetrazole molecule. The results indicate that the adsorption of tetrazole through the N2 position (leading to the 1H tautomer) on an anatase TiO2 surface is favored over adsorption through the N1 position. In addition, it was observed that the photocatalytic activity of tetrazole-doped TiO2 is higher than that of a pure anatase TiO2 surface.