Two novel Bi-based oxychloride photocatalysts: Synthesis, optical property and visible-light-responsive photocatalytic activity

Two novel visible-light-responsive bismuth oxychloride photocatalysts Bi2EuO4Cl and Bi2NdO4Cl have been successfully developed via a solid-state reaction route. Their crystal structures and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), diffuse reflectance spectra (DRS), and photoluminescence (PL) spectra. Fascinatingly, both the compounds possess considerable optical absorption in a broad region ranging from UV light to visible light. The indirect-transition optical band gaps of Bi2EuO4Cl and Bi2NdO4Cl are estimated to be 2.21 and 1.89 eV, respectively. For the first time, their photocatalytic activities were determined by photodecomposition of methylene blue (MB) in aqueous solution under visible light (λ>420 nm). The results revealed that both Bi2EuO4Cl and Bi2NdO4Cl can be used as effective visible-light-driven photocatalysts. In addition, theoretical calculations on the electronic structure, orbital constitutions and optical absorption of Bi2NdO4Cl were also performed. These findings shed light on the exploration of new photocatalytic materials activated by visible light.