Nickel substituted polyoxometalates in layered double hydroxides as metal-based nanomaterial of POM-LDH for green catalysis effects.

Three nickel substituted Keggin-type polyoxometalates, α-[SiWO{Ni(HO)}] (denoted as SiWNi), was intercalated into ZnAl based Layered Double Hydroxide (ZnAl-LDH) by the selective ion-exchange technique. The as-synthesized nanocomposite, SiWNi@ZnAl, was used as heterogeneous nanoreactor to promote the synthesis of drug-like aminoimidazopyridine small molecule skeletons via the well-known Ugi-type Groebke-Blackburn-Bienaymé reaction (GBB 3-CRs) in the absence of any acid/additive and under mild and solvent-free conditions. A synergistic catalytic effect between SiWNi polyoxometalate and ZnAl-LDH precursors is evidenced by a higher catalytic property of the SiWNi@ZnAl composite compared to the individual constituents separately.

Sandwich type polyoxometalates encapsulated into the mesoporous material: synthesis, characterization and catalytic application in the selective oxidation of sulfides.

The A-type sandwich polyoxometalates of [(HOSnOH)(PWO)] (PWSn) and [(OCeO)(PWO)] (PWCe) were immobilized for the first time into the porous metal-organic framework MIL-101(Cr). FT-IR, powder X-ray diffraction, SEM-EDX, ICP analysis, N adsorption and thermogravimetric analysis collectively confirmed immobilization and good distribution of polyoxometalates into cages of MIL-101(Cr). The catalytic activities of the homogeneous PWSn and PWCe and the corresponding heterogeneous catalysts were examined in the oxidation of sulfides to sulfones with HO as the oxidant at room temperature.

Enhanced photocatalytic activity of nanocomposites of TiO2 doped with Zr, Y or Ce polyoxometalates for degradation of methyl orange dye.

The synergistic effect of polyoxometalate (POM) and metal-doped TiO2 (metal = Zr, Y and Ce) was examined, to fabricate nanocomposites with enhanced photocatalytic activities toward the degradation of methyl orange (MO), as a model textile dye. A series of new nanocomposites, containing different loading amounts of H9Na3[WZn3(H2O)2(ZnW9O34)2].24H2O (HZnW) (10-30%) on each of the metal-doped TiO2 nanoparticles, were synthesized using impregnation method.