ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Investigating the chemical and physical aspects: optical and electrical properties of TiO₂, TiO₂: Fe, and Fe/ TiO₂ (111) through DFT analysis

Qaiser Rafiq, Sikander Azam, Sardar Sikandar Hayat, Usman Javed, Asif Mahmood, and Saleem Ayaz Khan

Department of Physics, Islamic International University, Islamabad, Pakistan

E-mail: sikander.physicst@gmail.com

Received: 6 June 2023  Accepted: 24 August 2023

Abstract:

The development of a thin film titanium dioxide (TiO₂) depends on an understanding of complex electronic structure and charge transport properties. The utilization of simulation studies will help us understand the complicated system at the atomic level. Here, utilizing Hubbard's modified first-principles density functional theory (DFT + U), a theoretically created thin film TiO₂ (111) interface model is provided. Generalized gradient approximation with Perdew-Burke-Ernzerhof assistance (GGA + PBE) was used to model structural properties, while Hubbard's modified (GGA + U) exchange correlation functional was used to simulate optoelectronic properties. The addition, i.e., doping and adsorption, of Fe to the TiO₂ rutile (111) surface transfers its bandgap energy from 2.95 eV to a metallic nature, thereby enhancing its responsiveness to visible light by lowering the energy required for electron transitions. The enhanced visible light absorption and efficient charge separation worked together to significantly improve the hybrid photo catalyst’s photocatalytic performance. The research utilized the DFT method along with the (GGA + U) technique to evaluate both the band structure and density of states (DOS). The analysis of the electronic structure shows that the band gap for the pristine but for the doped and adsorbed systems the nature of the materials changes to metallic. The DOS calculations indicate hybridization between O-orbitals and Fe-orbitals in the vicinity of the conduction band minimum for both channels due to the doped system, and for the maximum in the case of the adsorbed system, the impurity introduces an energy level that lowers the band gap. The research carried out computations to determine the band structure and density of states for (TiO₂) doped with Fe and Fe-adsorbed. The results demonstrate that the doped and adsorption is considered to be a more advantageous approach than the pristine because of the maximum absorption in visible region. When the Fe atoms are adsorbed on TiO₂ (111), there is a maximum increase in the adsorption energy. The study examines the photo activity mechanism by investigating the impact of Fe on the semiconductor's absorption edge. This type of semiconductor, with Fe adsorbed on TiO₂ (111), has potential applications in the fields of photovoltaic, photocells, and electronics.

Keywords: Optical properties; Electrical properties; Surface study; DFT analysis

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03078-7

Chemical Papers 78 (1) 283–294 (2024)