Absorption mechanism of dopamine/DOPAC-modified TiO2 nanoparticles by time-dependent density functional theory calculations

Donor-modified TiO2 nanoparticles are interesting hybrid systems shifting the absorption edge of this semiconductor from ultra-violet to visible or infrared light spectrum, which is a benefit for several applications ranging photochemistry, photocatalysis, photovoltaics, photodynamic therapy. Here, we investigate properties two catechol-like molecules, that is, dopamine and DOPAC ligands, when anchored spherical anatase nanoparticle realistic size (2.2 nm), by means time-dependent density functional theory calculations. By differential absorbance spectra with bare nanoparticle, show how it possible determine injection mechanism. Since new low-energy peaks observed, infer direct charge transfer injection, which, unexpectedly, does not involve lowest energy conduction band states. We also find more perpendicular molecular benzene ring surface, intense absorption, suggests aiming at high packing in synthesis. Through comparative investigation flat surface model, unravel both curvature coverage effects.