Modulation of electronic structures in N-doped TiO2(B) for hydrogen evolution: A density functional theory study

Abstract

N-doping is an effective technique for enhancing the exploitation of TiO₂ under visible light, thanks to the level of doping introduced. It is also important to explore N-doping in the metastable polymorph TiO₂(B), which is renowned for its applications in energy materials. In order to investigate the impact of N-doping on the optical properties of TiO₂(B), a systematic comparison of the electronic structural and optical properties of pure and N-doped TiO₂(B) was conducted using density function theory (DFT) calculations. The results indicate that N-doping is more thermodynamically favorable at the O site with four coordinated atoms. Upon N-doping, impurity states emerged within the bandgap of TiO₂(B), leading to a significant reduction in the energy gap. Consequently, N-doping primarily enhances the absorbance of visible light, which is crucial for photocatalysis. Furthermore, the adsorption energy of H at the (0 0 1) surface of N-doped TiO₂(B) decreased by 2.75 eV, providing valuable insight for the design of TiO₂(B) with exceptional photo- and electro-catalytic performance.