Nonaqueous Synthesis of a Bismuth Vanadate Photocatalyst By Using Microwave Heating: Photooxidation versus Photosensitized Decomposition in Visible-Light-Driven Photocatalysis

A new synthetic route to monoclinic bismuth vanadate using a concept adapted from a nonaqueous synthesis strategy for nanostructured organic-inorganic hybrid materials and metal oxides, introduced recently as twin polymerization, is reported. Microwave-assisted synthesis starting from bismuth(III) tert-butoxide and vanadium(V) oxytri(tert-butoxide) in the presence of 2-methoxybenzyl alcohol, 2,4-dimethoxybenzyl alcohol, and 2-(2-thienyl) iso-propyl alcohol gave hybrid materials, which were characterized by solid-state C-13 NMR spectroscopy, CH analysis, atomic absorption spectroscopy, and energy dispersive X-ray spectroscopy. Subsequent pyrolysis resulted in nanoscale monoclinic bismuth vanadate that showed a high photocatalytic activity. The photocatalytic decomposition of model pollutants such as rhodamine B (RhB), methyl orange, methylene blue, and orange G under visible-light irradiation using the as-prepared bismuth vanadate samples was studied with a focus on the influence of the agglomeration behavior. The interplay between the photooxidation of RhB, induced by the excitation of the catalyst using visible light, and the photosensitized decomposition pathway is demonstrated by degradation experiments in solution and the solid state.