Structural analysis and photocatalytic activities of bismuth-lanthanide oxide perovskites

A series of pure bismuth-lanthanide oxide perovskites of the formula of BiLnO3 (Ln = Sm, Eu, Tb, Er and Ho) has been synthesized via simple sol-gel methods. The elemental compositions and valence states of these materials were confirmed by X-ray photoelectron spectroscopy (XPS). Powder X-ray diffraction spectroscopy (PXRD) revealed an isostructural cubic system of BiEuO3, BiTbO3 BiErO3 and BiHoO3, whereas BiSmO3 adapted a rhombohedral system. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were employed to further characterize and analyze the structure of these mixed metal oxides. Band gap mea-surements obtained using diffuse reflectance spectroscopy (DRS) revealed potential photocatalytic activities of BiLnO3 in the visible light region (2.14 eV, 2.23 eV, 1.50 eV, 2.10 eV and 2.13 for BiSmO3, BiEuO3, BiTbO3, BiErO3 and BiHoO3 respectively). Accordingly, the photocatalytic performances of BiLnO3 were investigated for the cyclic carbonate formation by CO2 cycloaddition reaction to multiple epoxides. Reaction yields of the re-ported photocatalysts varied up to 99.9% depending on the epoxide substrate used. The simple sol-gel route explained in this report offers an easy, low-cost, environmentally friendly synthesis of highly efficient photo-catalysts for a potential variety of photochemical reactions.