Structural transformation of Bi 1−x/3 V 1−x Mo x O 4 solid solutions for light-driven water oxidation

The influence of molybdenum content in the solid solutions of Bi 1−x/3 V 1−x Mo x O 4 ( x = 0.05–0.20) on the morphology, band gap, structure and light-driven water oxidation properties has been studied by scanning electron microscopy, X-ray powder diffraction and vibrational spectroscopy (Raman and infrared). To find out the peculiarities of structural changes for bismuth scheelite-related oxides containing both vanadium and molybdenum crystals of Bi 0.98 V 0.93 Mo 0.07 O 4 have been grown from a K–Bi–V–Mo–O high-temperature melt and characterized by single crystal X-ray diffraction. For the scheelite-related framework both V and Mo were found to occupy the same positions lowering the point group symmetry of tetrahedra from 4/ m to 2/ m giving monoclinic distortion for solid solutions with x = 0.05–0.10. The most promising photocatalytic performance was obtained for Bi 0.96 Mo 0.10 V 0.90 O 4 , in which the oxygen evolution could reach 21 μM in 50 s under visible light of LEDs, λ = 470 ± 10 nm, and 820 μE cm −2 s −1 . The changes in catalytic properties are shown to be governed by a crystal structure strain with a maximum obtained for the boundary sample between the monoclinic and tetragonal phase.