Controlled growth and photocatalytic properties of CdS nanocrystals implanted in layered metal hydroxide matrixes.

Layered double hydroxide Cd(1)(-)(x)()Al(x)()(OH)(2)(DS)(x)().3.0H(2)O (CdAlDS) and a related hydroxide salt compound Cd(2)(OH)(3)(DS).2.5H(2)O (CdDS), where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic layers, have been synthesized and used as precursors for CdS nanoparticle growth. Through a gas/solid reaction, CdS nanocrystals implanted in the layer matrixes of the layered double hydroxides are grown, and the sizes of the nanocrystals vary in the range of 3-6 nm in diameter. The presence of trivalent Al cations in the layered double hydroxide can be taken advantage of to control the size of the CdS nanocrystals, and it also helps to prevent the formed nanocrystals from extraction from the solid matrixes. The nano-CdS implanted composite exhibits high photocatalytic activity for degradation of the nonbiodegradable rhodamine B under both UV and visible irradiations.

Construction of a microporous inorganic-organic hybrid compound with uranyl units.

A uranium-nickel-organic hybrid compound with micropores has been assembled from a hydrothermal system, and this compound exhibits photocatalytic activities for the degradation of methyl blue as a model pollutant.

Preparation, structures, and photocatalytic properties of three new uranyl-organic assembly compounds.

Three new uranyl-organic coordination polymers (UO2)8(NDC)12(4,4'-bipyH2)3(4,4'-bipyH)3 (1), (UO2)3O[Ag(2,2'-bipy)2]2(NDC)3 (2), and (UO2)2(NDC)2(2,2'-bipy)2 (3), where NDC=1,4-naphthalenedicarboxylate and bipy=bipyridine, have been prepared in hydrothermal conditions. Both 1 and 2 possess a 2D structure while 3 is composed of 1D zigzag chains. In 1 there are mononuclear pentagonal-bipyramidal U-O polyhedra and 1D channels filled with 4,4'-bipy molecules, whereas in 2 there are mononuclear hexagonal-bipyramidal U-O polyhedra and tetranuclear pentagonal-bipyramidal U-O clusters which form 2D channels with occluded [Ag(2,2'-bipy)2]+ counterions. In 3 both the NDC and the bipy ligands coordinate to uranyl centers, leading to hexagonal-bipyramidal polyhedra which are connected to form 1D zigzag chains. Under UV or visible irradiation, 1 and 2 degrade rhodamine B with similar efficiency. The correlation between photocatalytic reaction rate and oxygen concentration for 1 and 2 has also been elucidated. Crystal data: 1, triclinic, space group P1, a=11.037(2) A, b=15.126(3) A, c=15.660(3) A, alpha=62.05(3) degrees, beta=72.26(3) degrees, gamma=82.05(3) degrees, and Z=2; 2, triclinic, space group P1, a=14.161(3) A, b=15.122(3) A, c=18.212(4) A, alpha=85.73(3) degrees, beta=76.99(3) degrees, gamma=67.32(3) degrees, and Z=2; 3, monoclinic, space group P2(1)/n, a=10.7976(18) A, b=31.501(6) A, c=11.590(2) A, beta=97.609(4) degrees, and Z=4.

Water-insoluble Ag-U-organic assemblies with photocatalytic activity.

Two metal-organic coordination polymers [Ag(bipy)(UO(2))(bdc)(1.5)] (bipy=2,2'-bipyridyl, bdc=1,4-benzenedicarboxylate) and [Ag(2)(phen)(2)UO(2)(btec)] (phen=1,10-phenanthroline, btec=1,2,4,5-benzenetetracarboxylate) were obtained by hydrothermal assembly of the d(10) metal silver and the 5f metal uranium with mixed ligands. Both compounds form two-dimensional networks with pi-pi overlap interactions between the aromatic fragments in the neighboring layers. In aqueous suspension the two water-insoluble materials show photocatalytic degradation performance superior to that of commercial TiO(2) (Degussa P-25) when tested on nonbiodegradable rhodamine B (RhB) as model pollutant. The relationship between the structure of the photocatalysts and the photocatalytic activity was also elucidated. On the basis of the monitored intermediate species and the final mineralized products, it is proposed that the possible reaction mechanism for the photodegradation (oxidation) of RhB in aqueous solution catalyzed by the two assembly compounds involves photoexcitation of uranyl centers and molecular oxygen.