First principles study of optical properties of Ni- and Pd-doped TiO2 as visible light catalyst

Doping TiO₂ with noble metals, transition metals, cations, anions have yielded very promising results in enhancing photocatalytic activity of TiO₂ in the visible region and its role in generating alternate forms of energy. Noble metals in general can effectively slow down carrier recombination. However, the study of Pd and Ni as dopant can lead to a reliable and versatile TiO₂-modified photocatalyst. In this paper, we explore the optical properties of Pd- and Ni-doped TiO₂ by doping with 4.17% Ni and Pd dopant concentrations. The optical properties prove that Ni-doped TiO₂ can absorb well in the visible region with an absorption coefficient of 1 × 10⁵ cm⁻¹. Hence, Ni-doped TiO₂ can successfully alter the electronic and optical properties of TiO₂ for favorable future applications. In the visible region, absorption coefficient of Pd-doped TiO₂ supercell is around 1.2 × 10⁵ cm⁻¹ which is comparatively greater than that of pure TiO₂ confirming its utility as a versatile and viable visible light photocatalyst. The other optical properties like reflectivity, refractivity, extinction coefficient and electron energy loss spectrum have also been studied.