Two Bi-based phosphate photocatalysts: Crystal structure, optical property and photocatalytic activity

Two Bi-based phosphate photocatalytic materials Na3Bi2(PO4)3 and Na3Bi(PO4)2 have been successfully synthesized by a solid-state reaction. Compared to BiPO4 with band gap 3.77 eV, the introduction of Na3PO4 resulted in smaller band gaps of 3.6 and 3.01 eV for Na3Bi2(PO4)3 and Na3Bi(PO4)2, respectively. The photocatalytic activities of the samples were determined by photooxidative decomposition of methylene blue (MB) in aqueous solution. The results revealed that both Na3Bi(PO4)2 and Na3Bi2(PO4)3 can be used as effective photocatalysts under UV irradiation, and the former exhibits a higher photocatalytic activity compared to BiPO4, which may be attributed to more light absorption in the UV range. It is a novel way to regulate the band-gaps of semiconductors and explore new photocatalytic materials.