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Use of silicon dioxide (SiO 2 ) and titanium dioxide (TiO 2 ) have been widely investigated individually in coatings technology, but their combined properties promote compatibility for different innovative applications. For example, the photocatalytic properties of TiO 2 coatings, when exposed to UV light, have interesting environmental applications, such as air purification, self-cleaning and antibacterial properties. However, as reported in different pilot projects, serious durability problems, associated with the adhesion between the substrate and TiO 2 , have been evidenced. Thus, the aim of this work is to synthesize SiO 2 together with TiO 2 to increase the durability of the photocatalytic coating without affecting its photocatalytic potential. Therefore, synthesis using sonochemistry, synthesis without sonochemistry, physical characterization, photocatalytic evaluation, and durability of the SiO 2 , SiO 2 @TiO 2 and TiO 2 coatings are presented. Results indicate that using SiO 2 improved the durability of the TiO 2 coating without affecting its photocatalytic properties. Thus, this novel SiO 2 @TiO 2 coating shows potential for developing long-lasting, self-cleaning and air-purifying construction materials.

Abstract:The effect of the TiO 2 addition on the physicomechanical properties of a geopolymer system based on metakaolin (MK) and hydroxide and potassium silicate as activators is presented in this article. Three different liquid-solid systems (0.35, 0.40, and 0.45) and two titanium additions were investigated (5% and 10% of the cement content). The flowability, setting time, and mechanical strength of the geopolymer mixtures and their microstructural characteristics were evaluated using techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). It was concluded that a percentage of up to 10% TiO 2 does not affect the mechanical properties of the geopolymer, although it does reduce the fluidity and setting times of the mixture.