A theoretical exploration of catechol sensitization of C-doped bronze TiO2 surfaces for photochemical systems

Doping with atom impurities is currently an attractive mechanism to enhance the optical absorption capacity of TiO2 and other inorganic oxide semiconductors. In this work, the electronic and optical properties of carbondoped TiO2(B) (100) ultrathin surfaces were investigated using density functional theory (DFT) calculations, with the aim of evaluating their potential as photoelectrode for dye-sensitized solar cells (DSSCs). Carbon impurities were introduced onto oxygen sites located in the proximity of the surface and catechol was employed as a sensitizer model, focusing our study mainly on the evolution of the semiconductor's electronic structure. The reduction of the band gap energy resulting from impurity states within the valence band of C-doped TiO2(B) was confirmed. Moreover, our findings suggest that C doping not only induces a stronger interaction between the catechol molecule and the surface but also, could increase the light absorption capacity of the material. Thus, carbon-doped TiO2(B) could act as a promising semiconductor for DSSCs and other photochemical systems.