Computational studies on the interaction of vitamin C (ascorbic acid) with nitrogen modified TiO2 anatase nanoparticles

Density functional theory calculations were performed to investigate vitamin C interaction withN-doped TiO2 anatase nanoparticles. The adsorption of vitamin C on the energy favorable fivefoldcoordinated titanium sites was investigated. Various adsorption geometries of vitamin C towardsthe nanoparticle were examined. Since the adsorption energies of N-doped nanoparticles are higherthan those of undoped ones, the N-doped TiO2 nanoparticles can interact with vitamin C moleculemore strongly. Besides, adsorption on the pristine nanoparticle is less favorable, whereas on theN-doped one, the adsorption process is more energy favorable. The electronic structure analysis wasperformed in view of the density of states and molecular orbitals of the considered nanoparticles withthe adsorbed vitamin C molecule. The significant overlaps between the PDOS spectra of the oxygenatom of vitamin C molecule and titanium atom of TiO2 confirm the chemisorption of vitamin C onthe TiO2 nanoparticle. After the adsorption, the electronic densities in the HOMOs of the adsorptionsystems were mainly distributed over the vitamin C molecule, while the LUMOs were dominant atthe TiO2 nanoparticle. Our calculations shed light on understanding the interaction between vitamin Cand TiO2 nanoparticles, which provides an efficient outline for future experimental studies.