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The impact of drops on a porous surface with high contact-angle hysteresis and gas discharge is studied. Four different impact modes, ranging from complete repulsion to fast immobilization of a drop on the surface, are identified and mapped in a space spanned by the pressure difference of the gas across the porous surface and the impact Weber number of the drop. The most remarkable aspect of the dynamics is the transformation of a drop into a bubble, which occurs when a drop just overcomes the repulsion by the gas flow and wets the surface. The transition to the regime in which a drop is transformed to a bubble is well described by a simple scaling relationship based on a balance between inertia and the repulsive force due to the gas flow. [ABSTRACT FROM AUTHOR]

For a fixed porous framework, developing an efficient composite material with selective removal of oil and water from an oil–water mixture is of significance but challenging because of the effect of its decreased pore size and porosity and single wettability. Herein, a Janus fabric via a general strategy of surface hydrophobization, oxidation treatment, and chemical bath deposition is constructed. The obtained composite fabric consists of a hydrophilic Co-(CO3)0.5OH·0.11H2O nanoneedle/cotton fiber side and a hydrophobic cotton fiber side, which endows it with a unidirectional water transportation capability and exhibits an effective separation for both light and heavy oil–water mixtures under gravity. Especially using the water wetted composite fabric as a separation cell, the built-in lyophobic layer originating from fluid passed through the nonwetting region of wetted fabric decreases the unfavorable contact between lyophobic interface and separated liquid, and the permeation flux is enhanced by 214.5% for water and by 112.5% for oil, respectively, compared to that in the pristine fabric, whereas it has no effect on the separation efficiency of a heavy oil–water mixture. Meanwhile, the Janus composite fabric exhibits an excellent oil–water separation stability and durability and is easily recycled for long-term use. The facile Janus material synthesis strategy is available on various substrates including melamine sponge, Ni foam, cellulose paper, and other nanosheet arrays on cotton fabric. Thus, this work provides a route to develop multifunctional materials for potential application in quick oily wastewater remediation. [ABSTRACT FROM AUTHOR]

A transparent TiO 2 -C@TiO 2 -C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO 2 -C@TiO 2 -C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N 2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO 2 -C particle layers are intimately inhered to porous TiO 2 -C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO 2 and its surface carbon layer in TiO 2 -C particle promotes the generation of Ti- O -C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO 2 -C@TiO 2 -C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis. [ABSTRACT FROM AUTHOR]

Hydroxyapatite ( HAp) hollow microspheres with hierarchically porous structure and nanorice-like architecture units were synthesized by the composite-hydroxide approach. NH4 H2 PO4 was first reacted with hydroxides to form a hydroxide-insoluble M3 PO4 (the term M represents either Na or K). The diffusing M3 PO4 at the liquid-solid interface then reacted with the Ca( OH)2, forming insoluble HAp hollow spheres by Kirkendall process. Results show that when reaction time is increased from 3 to 12 h, the average diameter of the microspheres increased from 2.64 to 4.16 μm. In addition, the size homogeneity of the hollow microspheres was improved gradually due to Ostwald ripening. The prepared hollow microspheres were treated by ultrasound, and nanorice-like component units with a large mass of mesopores (<10 nm) were displayed. These prepared HAp hollow microspheres might be expected to apply to ion adsorption and drug delivery. [ABSTRACT FROM AUTHOR]

Abstract: TiO2/carbon paper composite materials with a hierarchically porous structure were synthesized by employing a filter paper as the support material and carbon source. The resorcinol–formaldehyde–block copolymer nanocomposite formed by the self-assembly of phenolic resin and F127 under acidic condition was selected as modifier of the microstructure of carbon paper. Results show that the as-adjusted carbon paper preserved the nanostructure of a pure carbonized filter paper. An ordered mesostructure was also formed. This micromorphology resulted in the increased specific surface area, as well as micropore and mesopore volumes, compared with the pure carbonized filter paper. When mesoporous TiO2 was deposited on the carbon paper with ordered mesopore by the evaporation-induced self-assembly route, the TiO2/carbon paper composite materials displayed excellent adsorption property and enhanced photocatalytic activity of methylene blue. [Copyright &y& Elsevier]

Abstract: The porous ZrO2 ceramics with ultra-high porosity were produced by combining phase change, heat exchange and freeze drying process of ZrO2 slurries during decompression environment. The prepared slurry was first cooled to near the supercooling point, and then the supercooled slurry was placed on decompression system to induce foaming and solidification until the decompress-freezing process of the slurry completed. After drying and sintering of the green part, an as-prepared ceramic with porosity more than 93% was obtained. It was shown that the porous ceramic was typically composed of large spherical cells, interconnected by near circular windows. Although the mechanical properties in obtained ceramics are not enough to resist high stress, porous ceramics with a number of pores in cell walls and struts may be expected to be applied in high thermal insulation process. [Copyright &y& Elsevier]

Two hierarchically porous silica ceramics with unidirectionally aligned channel morphology have been in situ synthesized by using soluble starch monoliths with well-defined uniaxial macroporous structure as template. Both these ceramics faithfully inherit the structure of soluble starch templates and show a large BET surface as well as a microstructure of uniform worm-like nanopores and a lamellar phase. These materials may be suitable for use in various separation and reaction processes. [Copyright &y& Elsevier]

Abstract: Gathering the photocatalysis of semiconductors and the superduper electron transmittability of graphene, graphene-based semiconductor photocatalytic composites are attracting increasing interest of researchers. In this paper, a Cu2O/reduced-graphene-oxide (Cu2O/RGO) nanocomposite was prepared via a facile wet-reduction process, for removal of organic pollutants. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and UV–vis spectrophotometry. The nanocomposite is composed of Cu2O nanoparticles with sizes of 100–500nm attached to the RGO sheets. For photodegradation of methylene blue (MB) under visible light, the Cu2O/RGO nanocomposites exhibited greatly enhanced photocatalytic efficiency compared to the pure Cu2O nanoparticles. The enhanced photocatalytic performance was mainly ascribed to the increased adsorptivity to organic dye as well as the efficient charge transportation and separation from Cu2O to RGO. [Copyright &y& Elsevier]

Exploiting photocatalysts/catalysts with characteristics of low cost, high reactivity and easy recovery is of great significance for energy efficiency and environmental remediation. Herein, CuO/TiO 2 hybrid nanofibers with different CuO contents were fabricated by a simple and low-cost method of electrospinning followed with calcinations in air. The hybrid nanofibers possess some distinct merits including mesoporous structure, extended light response range, and large TiO 2 /CuO interface. The CuO/TiO 2 hybrid nanofibers showed improved photocatalytic activity for organic dye degradation under both simulated sunlight (UV–vis) and visible light (λ > 420 nm), compared with pure TiO 2 nanofibers. Both processes exhibited humplike activity dependence upon CuO addition, with a peak at 1 wt.%-CuO content under UV–vis light and a peak at 5 wt.%-CuO content under visible light, respectively. The mechanism for the CuO-content dependent photocatalysis was discussed with the photoelectrochemical analysis in evidence. Moreover, the CuO/TiO 2 hybrid nanofibers exhibited very high catalytic efficiency for the reduction of nitrophenols by sodium borohydride, and the apparent reaction rate constants ascended with the increased CuO content. The optimized CuO/TiO 2 nanofibers are expected to act a highly efficient catalyst to replace the noble metals in this field. Therefore, this work demonstrated a convenient case for the exploitation of noble-metal-free catalysts with high efficiency, to meet the increasing demands of industrial applications at reduced costs. [ABSTRACT FROM AUTHOR]

The Au/TiO 2 hybrid nanofibers composed of mesoporous TiO 2 nanofibers and Au nanoparticles were synchronously fabricated by integrating a facile electrospinning technique and subsequent annealing in air. The Au loading content in the hybrid nanofibers was regulated by varying the dosage of chlorauric acid added in the precursor solution. The compositions, microstructures and optical response properties of the Au/TiO 2 hybrid nanofibers were characterized. The UV–vis spectra of the as-prepared hybrid fibers reveal two absorption bands belonging to the band gap absorption of TiO 2 and the surface plasmon resonance (SPR) of Au nanoparticles. For the catalytic reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride, the apparent reaction rate constant is raised but TOF value of the catalyst decreases, as the Au loading amount in the hybrid fibers increases. This is because the Au nanoparticles with smaller sizes have higher total surface areas at the same weight and therefore show higher catalytic activity. This method for producing Au/TiO 2 hybrid nanofibers is versatile and can be extended to the fabrication of other hybrid nanofibers composed of various noble metal nanoparticles and other mesoporous metal oxide nanofibers, designing of highly efficient catalysts for more important chemical reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • First preparation of dodecahedrons CeO 2 /Co/C for microwave absorption. • An excellent reflection loss of −68.83 dB at 5.92 GHz with ultra-thin thickness. • Effective absorption bandwidth up to 4.16 GHz under a single thickness. CeO 2 /Co/C dodecahedrons composites with excellent microwave absorption performance were synthesized by using a hydrothermal method. ZIF-67/CeO 2 was first prepared by introducing CeO 2 into the precursor of ZIF-67 and then CeO 2 /Co/C composite was obtained after heat treatment. Impedance matching of the samples could be well adjusted by controlling the content of CeO 2. Unique dodecahedral structure for more interfacial reflection and cerium dioxide oxygen vacancies enhance microwave absorption performance. Specifically, the CeO 2 /Co/C exhibited a minimum reflection loss of −68.83 dB is observed at 5.92 GHz, while the thickness was 3.69 mm. The introduction of CeO 2 effectively enhanced the impedance matching of the materials and improved the microwave absorption performance. Therefore, this CeO 2 /Co/C composite is a promising microwave absorber material with high performance. [ABSTRACT FROM AUTHOR]