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Tungsten trioxide (WO3) displays excellent performance in solar-related material applications. However, this material is rare and expensive. Therefore, developing efficient materials using smaller amounts of WO3 is inevitable. In this study, we investigated how to create high photocatalytic performance of WO3 particles containing platinum (Pt, as a co-catalyst) and homogeneously spherical macropores (as a medium to enable access of large molecules and light penetration into the remote internal regions of the catalyst). The present particles were prepared by spray drying of a precursor solution containing WO3 nanoparticles, Pt solution, and polystyrene (PS) spheres (as a colloidal template). Photocatalytic studies showed that changes in particle morphology (from dense with smooth surfaces, to dense with rough surfaces, to porous structures) and added Pt effectively improved the photocatalytic performance over WO3 nanoparticles. Our results showed that the best precursor (prepared using a PS/WO3 mass ratio of 0.32 and containing Pt co-catalyst) provided WO3 particles with a photocatalytic rate of more than 5 times that of pure 10 nm WO3 nanoparticles. Moreover, the catalyst can be effectively recycled without an apparent decrease in its photocatalytic activity. The experimental results were also supported by a proposal mechanism of the photocatalytic reaction phenomenon.

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Studies on preparation of porous material have attracted tremendous attention because existence of pores can provide material with excellent performances. However, current preparation reports described successful production of porous material with only partial information on charges, interactions, sizes, and compositions of the template and host materials. In this report, influences of self-assembly parameters (i.e., surface charge, size, and concentration of colloidal nanoparticles) on self-organized porous material fabrication were investigated. Silica nanoparticles (as a host material) and polystyrene (PS) spheres (as a template) were combined to produce self-assembly porous materials in film and particle forms. The experimental results showed that the porous structure and pore size were controllable and strongly depended on the self-assembly parameters. Materials containing highly ordered pores were effectively created only when process parameters fall within appropriate conditions (i.e., PS surface charge ≤ -30 mV; silica-to-PS size ratio ≤0.078; and silica-to-PS mass ratio of about 0.50). The investigation of the self-assembly parameter landscape was also completed using geometric considerations. Because optimization of these parameters provides significant information in regard to practical uses, results of this report could be relevant to other functional properties.

Information about correlation of material properties parameters (i.e., crystallite and particle sizes) and photocatalytic activity of tungsten trioxide (WO3) particles are still lacking. For this reason, the purpose of this study was to synthesize WO3 particles with controllable crystallite (from 18 to 50 nm) and particle sizes (from 58 to 677 nm) using a spray‐pyrolysis method and to investigate correlation of crystallite/particle size and photocatalytic activity. To gain control of crystallite/particle size, synthesis temperature (120–1300°C) and initial precursor concentration (2.5–15 mmol/L) were investigated, which were then compared with the proposal of the particle formation mechanism. The results showed that both crystallite and particle sizes played an important role in photocatalytic activity. In this research, the optimum condition to produce the highest photocatalytic performance of WO3 particles was at the temperature of 1200°C (crystallite size: 25 nm), and initial concentration of 10 mmol/L (particle size: 105 nm). © 2013 American Institute of Chemical Engineers AIChE J, 60: 41–49, 2014