Size effect and photocatalytic activity of the bismuth tungstates Bi2-xCexWO6 (with x = 0,0.5 and 1) in aqueous medium [Effet de taille et activité photocatalytique des tungstates de bismuth polycristallins Bi2-xCex WO6 (avec x=0,0,5 et 1) en milieu aqueux]

The aim of this study was to investigate the photocatalytic activity of polycrystalline phases of bismuth tungstatesof formula bi2-xcexwo6 with x = 0,0.5 and 1. the doped or pure bismuth tungstate phases were prepared by coprecipitation method and the obtained precursors were submitted to different calcination temperatures 300°c,400°c,600°c and 900°c. the bi2-xcexwo6powders were characterized by x-ray diffraction,and the orthorhombic structure of bi2wo6 was confirmed. the presence of a two-phase system in the case of substituted samples (x=0.5 and 1) was observed. all doped or substituted samples bi2-xcexwo6 presented a monoclinic phase,coexisting with a ceria phase ceo2.the photocatalytic activity of the as-prepared samples was studied by irradiating aqueous solutions of rhodamine b,associated with bi2wo6 additives having variable crystallite sizes. the photocatalytic activity of such bismuth tungstates increased as the crystallite sizes decreased.the bismuth tungstates bi2-xcexwo6 (x=0.5 and 1) were studied in the same experimental conditions: the photocatalytic activity appeared as being very low.