Photocatalytic Degradation of Gaseous Organic Species on Photonic Band-Gap Titania

Abstract

The use of photonic band gap (PBG) titania (inverse opal) for the photocatalytic degradation of an organic chemical in air is demonstrated in this study using 1,2-dichlorobenzene. A photonic band gap in the mid-to-high ultraviolet (UV) wavelength range (280-380 nm), normally associated with the optimal photocatalytic activity of anatase titania, is expected to increase the quantum efficiency for the catalyst. To achieve this band gap, porous structures with alternating air and titania spaces with a periodicity of about 150 nm is required. A thin film of porous photonic titania was synthesized in-situ on a quartz glass rod with a sol-gel technique using polystyrene micro-spheres as templates. Scanning electron microscopy images revealed a pore size of about 100 nm and a periodicity of approximately 150 nm, necessary for the desired band gap. X-ray diffraction studies of the coating showed the presence of anatase titania, which is known to exhibit photoactivity. The photocatalytic activity of the coated titania film was verified by measuring the degradation of 1,2-dichlorobenzene vapor in a semi-batch mode in the presence of UV radiation (mid-high UV wavelength) PBG titania showed 248% higher photonic efficiency compared to commercially available P25 titania catalyst. Transmission spectra from the thin films showed high absorbance in the UV range, suggesting a band gap in the region of UV illumination.

Assembly of large-area, highly ordered, crack-free inverse opal films

“…This scalable route to highly ordered, large-area, chemically tailorable inverse opal films may be utilized in a diverse range of applications. Due to the absence of an overlayer, the high porosity of the coassembled films is readily accessible from the top surface, which is especially important for applications in catalysis (10,15,16), gas adsorption (55), or tissue engineering (11,12). These single-domain periodic inverse opal films can also behave as large-area photonic band gap structures for applications in photonics (6-10).…”

“…Inverse opals can exhibit a high degree of interconnected porosity (approximately 75%) with extremely uniform size (average size normally in the range of 100-1000 nm) and periodic distributions of pores, achieved through colloidal monodispersity. Such structures have been shown to be potentially useful in a wide range of fields, including photonics (6-10), tissue engineering (11,12), sensing (13,14), and catalysis (10,15,16). However, whereas conventional self-assembly has yielded ordered inverse opal structures over modest (≤10 μm) length scales, such processes have been plagued by uncontrolled formation of defects over larger length scales (2,3), thus limiting their real-world applications.…”

Three‐Dimensionally Ordered Macroporous Titania with Structural and Photonic Effects for Enhanced Photocatalytic Efficiency

“…According to the modified Bragg's law, the photonic stop-band wavelength can be adjusted by controlling the pore size, according to Equations (1-3): [18] …”

Three-Phase Co-assembly: In Situ Incorporation of Nanoparticles into Tunable, Highly Ordered, Porous Silica Films

“…In particular, the interconnected periodic array of pores in the inverse opal structure, synthesized from a sacrificial colloidal crystal template, has made it a viable bottom-up materials candidate for applications in photonics, [1][2][3][4] tissue engineering, 5 sensing, 6,7 and catalysis. 8,9 However, in order to utilize these structures as functional materials, tuning the inverse opal composition is extremely important. The incorporation of metal nanoparticles into inverse opals has recently attracted particular attention in the literature.…”