Abstract
Barium niobium phosphate compounds (BaNb~2~P~2~O~11~ and Ba~3~Nb~2~P~4~O~18~), with corner‐sharing NbO~6~ octahedra as well as PO~4~ tetrahedra, were prepared by a conventional solid‐state reaction method, and their optical properties, electronic band structure, and photocatalytic activity were investigated. The powders were characterized by X‐ray powder diffraction (XRD), field‐emission SEM (FESEM), high‐resolution TEM (HRTEM), and UV/Vis and fluorescence spectroscopy. Both compounds exhibit similar optical band gaps, 3.55 eV for BaNb~2~P~2~O~11~ and 3.58 eV for Ba~3~Nb~2~P~4~O~18~. However, photoluminescence spectra revealed that a radiative recombination process of charge carriers is dominant in Ba~3~Nb~2~P~4~O~18~ (strong blue‐white emission at 300 K) under UV irradiation, whereas no obvious emission was observed from BaNb~2~P~2~O~11~. The photocatalytic activity for the evolution of H~2~ from the splitting of pure water was evaluated. BaNb~2~P~2~O~11~, which has a smaller photon emission at room temperature, exhibited a much higher photocatalytic activity than Ba~3~Nb~2~P~4~O~18~. The difference in the photocatalytic activity of the two compounds is attributed to their different electronic band structures, resulting from their different crystal‐structure environments.