Enhanced Photocatalytic Activity of N/Li2MoO4 Co-doped TiO2 Nanoparticles under Visible Light

Abstract

TiO₂-based nanomaterials have been extensively synthesized and used in a wide range of photocatalytic applications. The photocatalytic oxidation process, however, is only activated by irradiation with ultraviolet (UV) light which limits its indoor applications. Herein, to improve such limitations, N/Li₂MoO₄-doped TiO₂ nanoparticles were prepared via sol-gel method. Li₂MoO₄ concentration was varied. The catalysts were characterized by XRD, XPS, FE-SEM, and UV-Vis spectroscopy. As-synthesized N/Li₂MoO₄-doped TiO₂ catalysts exhibited their crystal sizes of as fine as 20 nm in diameter whereas that of the pure TiO₂ was about 35 nm. The absorption ranges of the N/ Li₂MoO₄-doped catalysts were relocated from UV region toward visible light region. The catalyst with 1 mol% Li₂MoO₄ offered the highest degradation rate of methylene blue (MB) solution upon visible light irradiation. Its fine crystal size, narrow band gap energy (2.82 eV), high defect concentration, and strong light absorption in visible region are responsible for the enhanced photocatalytic activity of the 1 mol% Li₂MoO₄.