Resonant waveguide grating fabrication on planar and cylindrical substrates using a photosensitive TiO₂ sol-gel approach

Abstract

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Influence of the Micro-Nanostructuring of Titanium Dioxide Films on the Photocatalytic Degradation of Formic Acid under UV Illumination

“…Its main advantages are its optical properties (a high refractive index, and transparency in the visible and NIR range) and its mechanical, physical and chemical properties (photocatalytic properties). The advantages of depositing TiO 2 coatings in the form of thin films have been demonstrated in many fields, including energy [ 11 ], photocatalysis [ 12 , 13 , 14 , 15 , 16 , 17 ], electronics [ 18 , 19 ], health [ 20 ], and optics [ 21 , 22 , 23 ]. Additionally, the coatings can be micro-nanostructured, thereby giving them new functionalities and properties, e.g., improved absorption efficiency [ 24 ], hydrophobicity and enhanced tribological properties [ 25 ].…”

“…These allow the creation of micro-nanostructures with few constraints on scale or resolution, but these approaches are generally limited to simple designs and small surface areas. In the top-down approach, nanostructures are constructed from bulk materials that are selectively patterned to remove some of the bulk, as in optical lithography [ 21 , 28 , 29 ]. The great majority of industrial nanofabrication techniques fall into this category.…”

“…In the present study, we used colloidal lithography to investigate the influence of patterning on the photocatalytic efficiency of sol-gel TiO 2 films. The sol-gel approach is a so-called “soft chemistry” technology, which allows the realization of glassy material such as TiO 2 without having to resort to high temperatures for its processing [ 21 , 29 , 32 ]. The material is directly fabricated from a viscous solution that can be easily deposited (e.g., by dip-coating or spin-coating) on small or large planar or non-planar substrates [ 21 , 29 , 32 ], which makes this method very adjustable.…”

“…The sol-gel approach is a so-called “soft chemistry” technology, which allows the realization of glassy material such as TiO 2 without having to resort to high temperatures for its processing [ 21 , 29 , 32 ]. The material is directly fabricated from a viscous solution that can be easily deposited (e.g., by dip-coating or spin-coating) on small or large planar or non-planar substrates [ 21 , 29 , 32 ], which makes this method very adjustable. Moreover, the sol-gel approach is interesting because the coatings can be photosensitive to UV radiation, which allows direct structuring without having to resort to etching steps [ 21 , 29 , 32 ], which is one of its main interests.…”

“…The material is directly fabricated from a viscous solution that can be easily deposited (e.g., by dip-coating or spin-coating) on small or large planar or non-planar substrates [ 21 , 29 , 32 ], which makes this method very adjustable. Moreover, the sol-gel approach is interesting because the coatings can be photosensitive to UV radiation, which allows direct structuring without having to resort to etching steps [ 21 , 29 , 32 ], which is one of its main interests. Micro-nanostructured and unstructured coatings were characterized using Raman spectroscopy, ellipsometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM).…”