Violet blue long-lasting phosphorescence properties of Mg-doped BaZrO3 and its ability to assist photocatalysis

•Violet blue long lasting phosphorescence is first observed in BaZrO3:Mg2+.•BaZrO3:Mg2+ can keep the photocatalytic activity of photocatalyst TiO2 in dark.•BaZrO3:Mg2+/TiO2 composites for photocatalysis are successfully obtained.

In this study, a novel Mg-doped BaZrO3 material with the perovskite structure was synthesized by solid-state reaction. Intense violet blue long-lasting phosphorescence (LLP) covering a wavelength range of 320–550 nm was observed for BaZrO3:Mg2+ for the first time, and this LLP wavelength range partially overlaps the absorption wavelength range of the commercial photocatalyst TiO2 (P25). This overlap indicates that Mg-doped BaZrO3 may assist the photocatalytic activity of TiO2. BaZrO3:Mg2+/TiO2 composites were synthesized by a sol–gel method, and the subsequent characterization of these composites suggested that TiO2 nanoparticles were successfully coated onto the surface of BaZrO3:Mg2+ bulk particles. The ability of BaZrO3:Mg2+ to assist the photocatalytic activity of TiO2 was evaluated through investigations of the decomposition of methylene blue. The results revealed that the violet blue LLP of BaZrO3:Mg2+ not only supports the photocatalytic activity of TiO2 in the absence of UV light but also significantly increases the photocatalytic activity of per unit mass of TiO2 under UV irradiation.