Enhanced Photocatalytic Activity of Ultrathin Ba₅Nb₄O₁₅ Two-Dimensional Nanosheets

Anisotropic two-dimensional (2D) nanosheets of the layered perovskite, Ba5Nb4O15, with thicknesses of 5-10 nm and lateral sizes of 300-1200 nm, were synthesized by a hydrothermal route. The influences of the 2D morphology of the material on the crystal and electronic structures, light absorption properties, and photocatalytic activity were investigated. The ultrathin nanosheets showed much-enhanced photocatalytic activity compared to both thick nanosheets (∼30 nm) and micrometer-sized particles for the evolution of H2 from water splitting under UV light illumination. This enhanced activity is predominantly attributed to the larger surface area, higher optical absorption, and charge separation ability of the 2D nanosheet, which results from the variation of the local crystal structure arising from the ultrathin morphology of the Ba5Nb4O15.