General synthesis and phase control of metal molybdate hydrates MMoO4 center dot nH(2)O (M = Co, Ni, Mn, n=0, 3/4, 1) nano/microcrystals by a hydrothermal approach: Magnetic, photocatalytic, and electrochemical properties

摘要

Different phases and morphologies of molybdate hydrates MMoO4 center dot nH(2)O (M = Co, Ni, Mn, n = 0, 3/4, 1) nano/microcrystals, which include NiMoO4 center dot H2O microflowers, MnMoO4 center dot H2O microparallelogram plates, and CoMoO4 center dot 3/4H(2)O microrods, can be selectively synthesized by a hydrothermal process. The pH and reaction temperature have a crucial influence on the synthesis and shape evolution of the final products. Uniform CoMoO4 center dot 3/4H(2)O and NiMoO4 center dot H2O nanorod bundles can be produced by a hydrothermal process with the assistance of PEG-400. The calcination Of CoMoO4 center dot 3/4H(2)O and NiMoO4 center dot H2O at 500 and 550 degrees C, respectively, allows the formation of monoclinic beta-CoMoO4 and alpha-NiMoO4. The antiferromagnetic property of MnMoO4 center dot H2O, MnMoO4, and CoMoO4 center dot 3/4H(2)O has been studied for the first time. The photocatalytic activity of metal molybdate particles with different morphologies has been tested by degradation of acid fuchsine under visible light. Electrochemical performances of MMoO4 (M = Ni, Co) nanorod bundles and MnMoO4 microrods have been evaluated.