Self-template synthesis of ATiO3 (A = Ba, Pb and Sr) perovskites for photocatalytic removal of NO

Abstract

In this study, we report a self-template hydrothermal method for the synthesis of ATiO₃ (A = Ba, Pb, and Sr) perovskites using anatase TiO₂ nanosheets as precursors. Under hydrothermal conditions, ATiO₃ with different structures and morphology can be obtained. These samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The growth mechanism of ATiO₃ was explored by XRD evaluation over different reaction time, and it was observed that PbTiO₃ grows most slowly among all the samples including BaTiO₃, SrTiO₃, Ba_xPb_1−xTiO₃ and Sr_xPb_1−xTiO₃. The diffusion of A site sources to the solid surface and the reaction at solid/liquid interface could dominate the growth of ATiO₃. All the as-prepared samples exhibited activities toward photocatalytic oxidation of NO at ppb level. Specifically, PbTiO₃ has revealed the highest activity under both full spectrum and visible-light irradiation (λ > 420 nm), whereas BaTiO₃ exhibited best selectivity for the formation of ionic species (NO₃⁻), which could be ascribed to different electronic structures and charge separation efficiency of ATiO₃. This study provides some important hints to tune the photocatalytic performances (activity and selectivity) of ATiO₃ through the modification of A site elements.