Synthesis, crystal structure and photocatalytic activity of new Dion-Jacobson type titanoniobates

New Dion-Jacobson type layered perovskite compounds A'Ln 2 Ti 2 NbO 10 (A′ ​= ​Rb, H; Ln ​= ​Pr, Nd) were synthesized for the first time. The phase and chemical purity of the compounds were proved by X-ray diffraction (XRD) and EDX. Compounds RbPr 2 Ti 2 NbO 10 and RbNd 2 Ti 2 NbO 10 were synthesized using solid-state reactions, whereas HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O were obtained from Rb-containing phases by ion-exchange reactions. Crystal structures of RbPr 2 Ti 2 NbO 10 (P4/mmm, a ​= ​0.38223 (1) nm, c ​= ​1.51485 (8) nm, R wp ​= ​3.87%) and RbNd 2 Ti 2 NbO 10 (P4/mmm, a ​= ​0.38153 (1) nm, c ​= ​1.51200 (6) nm, R wp ​= ​3.62%) were refined using the Rietveld method. The distortions of polyhedrons in the structures were studied in detail. The thermal behavior of compounds was established using DTA. The ion-exchange products were found to be metastable hydrates. Optical band gap, valence band edge and conduction band edge potentials of obtained compounds were calculated from diffuse reflectance spectroscopy data. Photocatalytic experiment of methylene blue degradation under ultraviolet (UV) light was conducted with ground synthesized compounds. The particle size distributions were measured by laser diffraction before and after grinding. RbNd 2 Ti 2 NbO 10 showed the highest photocatalytic activity, while HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O showed none. • Dion-Jacobson phases RbPr 2 Ti 2 NbO 10 , RbNd 2 Ti 2 NbO 10 , ​HPr 2 Ti 2 NbO 10 ·1.5H 2 O and HNd 2 Ti 2 NbO 10 ·2H 2 O were synthesized. • The crystal structures of RbPr 2 Ti 2 NbO 10 and RbNd 2 Ti 2 NbO 10 were refined using the Rietveld method. • Thermal stability of obtained phases was studied using DTA and TGA. • Optical band gaps, valence band and conduction band edges potentials were calculated from diffuse reflectance spectra. • All compound were tested in a reaction of photocatalytic decomposition of methylene blue. RbNd 2 Ti 2 NbO 10 showed highest photocatalytic activity.