| Environment problem is becoming more and more serious with the development of economy and growing population. Frank S Y found Ti O2 is a photocatalyst in the ultraviolet wavelengths in 1977, now Ti O2 is one of the most famous photocatalyst due to its low cost, high reactivity, chemical stability and non-toxicity.Recently, the photocatalytic activity of Bi Fe O3 with inverse opal structure has attracted a large amount of attention. because, almost Ti O2 only can use a little of solar light(3–5%) due to its wide bandgap(~3.2 e V). Bi Fe O3 has a relatively small bandgap(~2.18 e V) that is appropriate for the absorption of visible light, can efficiently make use of the solar energy, which consists largely of visible light, making it a promising candidate for a visible-light-driven photocatalyst. Moreover, the Bi Fe O3 inverse opals have the ferromagnetic property, making it easier to recycle. The Bi Fe O3 inverse opal films with the ordered macroporous structure exhibiting many desirable optics properties, such as slow photon phenomenon, possible light scattering effect, compared to the powders or conventional films can result in higher photocatalytic activity. Furthermore, the connected holes between the air balls, more surface area and pore volume of the Bi Fe O3 inverse opal films with open macroporous structures can contributes more reaction sites, increasing the surface reaction sites involved, making it favorable for catalysis.In this paper, Monodisperse polystyrene microspheres were synthesized by the emulsifier-free emulsion polymerization of styrene using potassium persulfate as the initiator. Four batches of spheres with the average diameter of 359 nm, 500 nm,712nm and 860 nm were synthesized, analyze the diameter change of the polystyrene microspheres in different reagent mass. Futher more, with the potassium or styrene increasing, the results reveal the diameter of the polystyrene microspheres are also increased.The spheres were self-assembled on the quartz substrates by the velocity controlled vertical deposition technique. When the room temperature is 25℃, the stable technological condition is: experiment temperature~38℃, peristaltic pump speed~1r/min, the mass fraction of polystyrene microspheres aqueous solution~ 1.5%, respectively. The optical band gap of templates are measured with spectrophotometer, and compared with the theoretical calculation of the band gap, the results are in good agreement. In order to effectively increase the mechanical strength of polystyrene opal photonic crystal template and the adhesion between the microspheres and quartz substrate, The samples are kept for 105℃ as the annealing temperature for 5 min in oven.The Bi Fe O3 inverse opal structures are synthesized by the sol-gel method. The affinity of the polystyrene template is good when the solvent’s volume ratio is deionized water: anhydrous ethanol = 1:1. Using the spin coating technology(1000 rad, 10 s; 2000 rad, 10 s) to fill the corresponding precursor in the voids between the polystyrene microspheres. Finally, the samples were annealing in air in 450℃ for 60 min to remove polystyrene opals. The Bi Fe O3 with inverse opal structure is a visible-light-driven photocatalyst due to its bandgap~2.18 e V using the cut-off adsorption wavelength λg=580n. The samples are characterized by the SEM and XRD results, and using the Rh B to analyzed the photocatalytic properties. Analyse the enhancement photocatalytic mechanism of the Bi Fe O3 with the inverse opal structures and the influence of different periodic photonic crystals... |
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