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[摘要]：The nanometer-scale molybdates/tungstates Fe(2) (MoO(4))(3), CoMoO(4), NiMoO(4), CuMoO(4), In(2)(MoO(4))(3), and CuWO(4) are synthesized via a polyol-mediated approach. All nanomaterials are obtained as spherical particles with mean diameters between 25 and 75 nm. Detailed characterization is carried out based on DLS, SEM, XRD, EDX, UV-visible, and luminescence spectroscopy. The as-prepared, non-crystalline nanoparticles already exhibit interesting material properties. CoMoO(4), CuWO(4), and Fe(2)(MoO(4))(3) show brilliant blue, green, and orange-yellow colors. Moreover, a surprisingly high photocatalytic activity is observed for as-prepared, non-crystalline CuWO(4) and In(2)(MoO(4))(3). Comparing the degradation of methylene blue in neutral water, CuWO(4) and In(2)(MoO(4))(3) are found to be 4.2 and 7.4 times faster in daylight than standard TiO(2) nanoparticles (i.e., Degussa P25). On short-timeframe sintering the nanomaterials become crystalline with an almost preserved particle size. Sintered In(2)(MoO(4))(3) (450 degrees C, 0.5 h) doped with europium (5 mol%) shows intense red luminescence with a quantum yield of 37%-39% upon UV excitation. Finally, sintered CuMoO(4) (600 degrees C, 1 h) supported on commercial porous SiO(2) substrates turns out to be well-suited for the oxidation of o-xylene to o-tolyl aldehyde by air, with a selectivity of 64%. |
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