Fabrication of highly ordered, macroporous Na2W4O13 arrays by spray pyrolysis using polystyrene colloidal crystals as templates

Abstract

Highly ordered, macropore arrays, that is, inverse opal structures, of Na2W4O13 were successfully synthesized by spray pyrolysis using polystyrene (PS) colloidal crystals as templates. A densely packed monolayer of monodisperse PS microspheres was deposited on a silica glass substrate by use of the Langmuir-Blodgett thin film technique. Subsequently, Na2W4O13 layers were deposited on the PS templates as a thin layer by spray pyrolysis of a 5(NH4)2O.12WO(3).5H2O-NaCl solution. The PS templates were, finally, removed by thermal treatment, generating a surface with features (inverse opal structures) located where the interstitial space of the densely hexagonal-packed PS microspheres had been. The macroporous structures obviously depended on the annealing conditions such as time and temperature. The macropores were basically hemispherical in shape and highly honeycombed arrangement, which corresponded well to the PS templates. The inverse opal textures of Na2W4O13 layer surfaces enhanced their hydrophobicity. The surfaces modified by fluoroalkylsilane (FAS) were converted from hydrophobic (water contact angle=127 degrees) to hydrophilic (30 degrees) by photocatalytic oxidation using the Na2W4O13 crystal layer. The Na2W4O13 crystals exhibited high activity for FAS photodegradation.

Structural design of TiO2-based photocatalyst for H2 production and degradation applications

“…A larger surface area increases the number of surface sites available to catalyze the reaction, thus enhancing reactant adsorption and product desorption. Compared to the most common nanostructured TiO 2 , such as the commercial TiO 2 nanoparticles (P25), TiO 2 with modified morphologies, such as nanotubes, [46][47][48][49] nanofibers, 50,51 nanorods, [52][53][54][55] foams, 56,57 and mesoporous structures [58][59][60][61] have larger surface area. It has been demonstrated that the photoconversion efficiency of TiO 2 nanotubes is almost twice that of spherical nanoparticles.…”

Unique three-dimensional nano-/micro-textured surfaces consisting of highly crystalline Nb2O5 nanotubes

“…Moreover, it has technological advantages from the viewpoints of its environmentally friendly nature, simplicity and low cost. The diameter of the pore size can be easily controlled in the range from 50 nm to $ 1 mm by changing the sizes of the colloidal spheres [2][3][4][5][6][7].…”

“…[1][2][3][4][5][6]. Macroporous structures have been widely studied and fabricated by various techniques, including anodization, lithography, solgel and reactive ion plating [1][2][3][4][5][6][7][8][9].…”

“…In many cases, densely packed microsphere templates have been fabricated using the Langmuir-Blodgett film technique [2,6] because PS microspheres can be self-assembled into ordered two-dimensional (2-D) arrays at an air-liquid interface.…”

Fabrication of two-dimensional close-packed shell structure in ceramic thin films

“…Monodispersed polystyrene and polymethyl methacrylate (PMMA) have been employed to fabricate MCCs [10][11][12]. The principle of NSL is as follows: first, polystyrene (PS) or PMMA MCCs are fabricated on the substrate by self-assembly or spin coating; then, a film is coated on the MCCs by solution casting [13,14], spray pyrolysis [15], electrochemical deposition, or physical vapour deposition, which includes sputtering [16][17][18][19] and subsequent pulsed laser deposition (PLD) [7]. Finally, the MCCs are removed to form a 2D nanostructure.…”