Efficient methylene blue removal over hydrothermally synthesized starlike BiVO₄

Nanoplate-stacked starlike BiVO₄ products have been successfully synthesized by a hydrothermal method, where a water/ethanol mixture was the solvent and ethylenediamine tetraacetic acid (EDTA) was the chelating agent. The molar ratio of EDTA to Bi³⁺ was found to play an important role in the formation of this morphology. These starlike BiVO₄ samples exhibited a high visible-light-driven photocatalytic efficiency. For the degradation of methylene blue (MB) under visible-light irradiation (λ > 420 nm), about 91% of the MB was degraded within 25 min. This is much higher than for BiVO₄ samples prepared by solid-state reaction (bulk BiVO₄) and other hydrothermal synthesis methods. The reasons for the differences in the photocatalytic activities of these BiVO₄ samples were further investigated.