Atomistic modulating of structural, elastic, and optoelectronic behavior of pure TiO2 and Fe/TiO2 for photoelectrochemical water splitting application

Abstract

Titanium dioxide (TiO₂) has attracted much attention because of their desirable physicochemical properties especially in the water splitting process. In this work pure and Fe-doped TiO₂ compounds are studies theoretically with the help of Generalized Gradient Approximation with the revised Pardew–Burke–Ernzerh (RPBE) exchange–correlation scheme. Total Density of States (TDOS) and Partial Density of States (DOS) were analyzed in detail which show that iron (Fe) and oxygen (O) orbitals hybridize, especially in the region of the doping system conduction band minima for both modes. Additionally, this interaction produces an energy level that effectively reduces the bandgap of the adsorbed system. Optical properties were elucidated which shows that Fe-doped TiO₂ system results in high absorption and photoconductivity. Moreover, the results demonstrate low bandgap energy which is suitable for the reduction in water splitting without the need for external energy. Magnetic properties demonstrated that Fe-doped TiO₂ systems show very low diamagnetic responses. The calculated elastic properties of Fe-doped TiO₂ indicate ductile nature of the material with a strong average bond strength. Fe-doped TiO₂ exhibited less microcracks with a mechanically stable composition.