oa Optimization Of The Electronic And Optical Properties Of Tio2 For Clean Fuel Production

Among different crystal structures and morphologies of TiO2, vertically oriented anatase nanotube arrays show the highest activity for solar energy conversion. However, the long-standing bottleneck is the fact that TiO2 is a wide band gap semiconductor, limiting its activation to the deep-blue and ultraviolet spectral region that contains but a small fraction (5%) of the incident solar energy. Herein, density functional theory (DFT) has been used to compare between density of states of bulk and nanotube forms of TiO2 by using different concentrations of N atoms. The wave functions were described using two different techniques; linear combination of atomic orbital (LCAO) and plane wave. Our results showed a shift in the calculated bandgap for bulk TiO2 only for small concentrations of N atoms as dopant. For TiO2 nanotube, the bandgap decreases as the concentration of N atoms increases. The effect of the diameter of TiO2 nanotubes on their optical and structural properties has also been investigated and discussed in details. Our study presents a protocol to fine tune the optical, electronic and structural properties of TiO2 for energy conversion applications.