Visible light-driven photocatalytic activity of wide band gap ATiO (A = Sr, Zn and Cd) perovskites by lanthanide doping and the formation of a mesoporous heterostructure with ZnS QDs.

Charge carrier recombination and wide band gap energy are still the main challenges in the visible-light-driven photocatalytic applications of titanate perovskites, ATiO. Herein, three strategies are rationally used to achieve a titanate-based photocatalyst with high photocatalytic performance under visible light. In the first step, SrTiO, ZnTiO, and CdTiO perovskites were synthesized and their photocatalytic activity was evaluated in the degradation of methylene blue (MB) and bisphenol A (BPA). Then, a dysprosium cation (Dy) was doped into an ATiO crystalline lattice. Systematic investigations indicate that Dy doping in SrTiO and CdTiO extends the ligand to metal charge transfer absorption edge to visible wavelengths leading to the activation of doped perovskites under visible light. Higher visible-light-driven photocatalytic performance (73.29% for MB and 52.57% for BPA) and higher total organic carbon (TOC) removal (59.20% for MB and 39.53% for BPA) have been achieved by Dy doped CdTiO compared to other photocatalysts. Finally, we prepared a Dy-CdTP/ZnS QD mesoporous type-II heterostructure by the growth of ZnS QDs on a flower-like Dy-CdTP. This design accelerates the separation and transfer of photogenerated electron-hole pairs. The surface area of the Dy-CdTP/ZnS QD heterostructure was ∼11.6 times greater than that of Dy-CdTP, offering a large surface area for the adsorption of organics, and abundant active sites for photocatalytic degradation. Taking advantage of the large surface area and considerable suppressing of the charge carrier recombination, the optimized Dy-CdTP(0.6)/ZnS QD photocatalyst exhibits excellent and stable performance for the degradation of MB (98.25%) and BPA (89.12%) with their considerable mineralization under visible light.