The development of novel nanostructured materials with controlled shapes and ordered morphology has stimulated great research interest for seeking novel properties and tailorable functions. In particular, nanostructured ZnO, a remarkable semiconducting oxide with a broad, direct bandgap, received much attention for its potential applications such as UV lasing, electro-optical switches, chemical sensors, photocatalysts, and dye-sensitized solar cells. A series of ZnO nanostructures, such as nanowires, [1][2][3][4] nanorod arrays, [3,[5][6][7] nanobelts, [8] nanoneedle arrays, [9] nanorings, [10] and nanosheets [11,12] have been successfully synthesized. Recently, Eiji et al. [12] reported that ZnO films formed with upright standing nanosheets on substrates induce a very high conversion efficiency for dye-sensitized solar cells because of the easy diffusion of electrolytes in the direction perpendicular to the substrates. However, because the diffusion of electrolytes in the direction parallel to the substrate is still difficult in the nanosheet films, the conversion efficiency would further increase if the nanosheet was macroporous. On the other hand, nanosheets with ordered pore periodicity have a wide range of potential applications including photonic crystals, [13] nanosieve filters, [14,15] masks, [16] and catalysts. [17] Moreover, the modulation induced by both nanoscale thickness and periodic macroporous structure may result in more exciting properties, for example, subwavelength imaging by a photonic-crystal slab.[18]The 3D colloidal crystal template technique is one of the most versatile and efficient techniques for creating 3D periodic macroporous structures, such as inverse opals. [19][20][21][22] However, the fabrication of 2D ordered pore periodicity in a nanosheet whose direction is nearly vertical to the substrate using this method has not been reported. Here, we extend the colloidal crystal template technique to assist the electrochemical deposition of ZnO nanosheet structures and, thus, create 2D hexagonal pore periodicity on nanosheets. Indium tin oxide (ITO) coated glass is used as an electrochemical deposition working electrode. The synthetic polystyrene colloidal crystals are coated onto the ITO glass as templates. ZnO nanosheets with ordered pore periodicity are obtained by the electrochemical deposition of zinc hydroxide nitrate hydrate (ZHNH) into the interstices of colloidal-crystal arrays and the subsequent removal of the templates under calcination. The spatial arrangement of ZnO nanosheets with ordered pore periodicity on ITO substrates is largely affected by the colloidal crystal template assisted crystallization process. Figure 1a shows a scanning electron microscopy (SEM) image of the cross section of a colloidal crystal template that was made from polystyrene microspheres with a diameter of 270 nm on an ITO substrate. The colloidal crystal microspheres have a high degree of order in all directions on the substrate. The thickness of the microsphere arrays is estimated to be 6-7 lm, co...

A novel filter material for separating and eliminating microorganisms in water and gas was fabricated by incorporating silver ions into porous hydroxyapatite (HA) ceramics prepared by a starch additive technique. The porous ceramics reveal a microstructure of both large and small pores. Microorganism separating and eliminating properties of the porous silver-incorporated HA ceramics (PHA-Ag) were investigated by bacterial and viral filtration tests. The PHA-Ag demonstrated excellent separating and antibacterial effects on Escherichia coli and the mechanisms were studied. Adsorption of bacterial cells to the HA and the barricading effect of small pores contribute to the separating property of PHA-Ag, while the Ag+ ions equip the ceramics with antibacterial property. Furthermore, the PHA-Ag exhibited an observable virus-eliminating property and its probable mechanism was also discussed.

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ZnS/ZnO doped silica glass inverse opals were prepared by a sol-gel chemistry method via polystyrene colloidal crystals templating. After the infilling precursors were solidified in the void space among polystyrene spheres, the polymer templates were removed by calcinations and the doped silica glass films were generated with long-range order of the inverse replicas of the template arrays. The effective reflective index of the structure and reflective index of the doped silica glass is calculated by Bragg equation using wavelengths of optical stop band and periodicity diameters of the inverse opals. The result is well agreed with mixture rule approximation.