[en] Highlights: • The electronic and optical properties of titanium dioxide was studied using GGA+U approach. • This study revealed charge generation upon protonation. • The phonon calculations confirmed that the system was in the ground state. • The optical properties of bulk TiO₂ show no absorbance in the visible solar region of the spectrum. A systematic study of electronic and optical properties of titanium dioxide under visible light was simulated using the first principles calculations. Both electronic and optical properties were studied. The findings support the application of TiO2 in photo energy generation after experimentally modifications. Our calculations were done using DFT with the GGA+U approach to mimic the experimental results and avoid underestimation of DFT. A theoretical band gap of 3.15 eV complimented the experimentally obtained band gap of 3.2 eV. Finally, our results revealed that upon protonation there is charge generation and this has the potential for application in photo energy generation.