Facet-, composition- and wavelength-dependent photocatalysis of Ag 2 MoO 4 .

Faceted β-Ag 2 MoO 4 microcrystals are prepared by controlled nucleation and growth in diethylene glycol (DEG) or dimethylsulfoxide (DMSO). Both serve as solvents for the liquid-phase synthesis and surface-active agents for the formation of faceted microcrystals. Due to its reducing properties, truncated β-Ag 2 MoO 4 @Ag octahedra are obtained in DEG. The synthesis in DMSO allows avoiding the formation of elemental silver and results in β-Ag 2 MoO 4 cubes and cuboctahedra. Due to its band gap of 3.2 eV, photocatalytic activation of β-Ag 2 MoO 4 is only possible under UV-light. To enable β-Ag 2 MoO 4 for absorption of visible light, silver-coated β-Ag 2 MoO 4 @Ag and Ag 2 (Mo 0.95 Cr 0.05 )O 4 with partial substitution of [MoO 4 ] 2- by [CrO 4 ] 2- were prepared, too. The photocatalytic activity of all the faceted microcrystals (truncated octahedra, cubes, cuboctahedra) and compositions (β-Ag 2 MoO 4 , β-Ag 2 MoO 4 @Ag, β-Ag 2 (Mo 0.95 Cr 0.05 )O 4 ) is compared with regard to the photocatalytic decomposition of rhodamine B and the influence of the respective faceting, composition and wavelength.