Synthesis routes to nanostructured titanium dioxides (spherical nanoparticles, nanotubes, mesostructure) have been studied. Their potential applications in various fields based on coating technology have been explored, i.e., dye-sensitized solar cells (using ruthenium sensitizer and some results of natural dyes), photocatalysts for self-cleaning films (TiO2 on textiles), antibacterial coating for multifunctional textiles (TiO2-SiO2 on cotton), and recent result on antifouling coating on wood. The synthesis/preparation procedures were developed to obtain green protocols based on combined techniques of hydro- or solvo-thermal (templated, seeded, deposition), sol–gel (templated, room temperature, dip coating), and solvent-casting techniques. Discussion on the properties and synthesis mechanism is presented. It will be shown that sonication has important role to shorten the preparation of nanotube titania and has been proposed as one green synthesis route. The changing of morphology of titanium dioxide has presented unexpected results to the shifting of photoactivity into visible irradiation.
Part of the book: Titanium Dioxide
This article will discuss natural dyes’ role, from colouring the cotton fabrics with some functionality to harvesting sunlight in the dye-sensitized solar cells. Natural dye colourants are identical to the low light- and wash-fastness. Therefore, an approach to improving the colourant’s physical properties is necessary. Colouring steps employing silica nanosol and chitosan will be presented. The first part will be these multifunctional natural dye coatings on cotton fabrics. Then, functionality such as hydrophobic surfaces natural dyed cotton fabrics will be discussed. Natural dyes are also potential for electronic application, such as solar cells. So, the second part will present natural dyes as the photosensitizers for solar cells. The dyes are adsorbed on a semiconductor oxide surface, such as TiO2 as the photoanode. Electrochemical study to explore natural dyes’ potential as sensitizer will be discussed, for example, natural dyes for Batik. Ideas in improving solar cell efficiency will be discussed by altering the photoanode’s morphology. The ideas to couple the natural dyes with an organic–inorganic hybrid of perovskite and carbon dots are then envisaged.
Part of the book: Dyes and Pigments