Preparation and phase transformation of Ag or Bi ion-exchanged layered niobate perovskite and their photocatalytic properties

抄録

Ag-intercalated and Bi-intercalated layered perovskite were fabricated by ion-exchanged process. The XRD and XPS confirm the phase transformation of the Ag-ion exchanged layered perovskite from Dion–Jacobson to Ruddlesden–Popper phase by heating at higher than 200°C. In the case of Bi ion-exchange perovskite, the product remained Dion–Jacobson phase during the heat treatment. For the Ag-intercalated sample, Ruddlesden–Popper type photocatalyst by heating at 500°C can degrade 20 ppm phenol solution to 6 ppm in 3 h under Xe light, which has superior photocatalytic activity to Dion–Jacobson phase Ag_0.67H_0.33LaNb₂O₇. For the Bi-intercalated sample, Dion–Jacobson type photocatalyst can degrade phenol from 20 to 12 ppm in 3 h. From first principle DFT simulation, high photocatalytic activity may be due to the new Ag 4d, O 2p and Nb 4d hybridized band at the highest of the valence band for Ag-included, and to the new Bi 6p band at the lowest of the conduction band for Bi-included samples.