The Synthesis of Anatase Nanoparticles and the Preparation of Photocatalytically Active Coatings Based on Wet Chemical Methods for Self-Cleaning Applications

Abstract

We report on an improved sol-gel method for the production of highly photocatalytic titanium dioxide (TiO 2 ) anatase nanoparticles which can provide appropriate control over the final characteristics of the nanoparticles, such as particle size, crystallinity, crystal structure, morphology, and also the degree of agglomeration. The synthesized anatase nanoparticles were characterized using various techniques, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and were tested in coatings for self-cleaning glass and ceramic surfaces. The coatings were prepared using a soft chemistry route and are completely transparent to visible light and exhibit a high photocatalytic effect, which was determined by contact-angle measurements. Finally, it is worth mentioning that both the sol-gel synthesis method and the coating-preparation method are based on a wet chemical process, thus presenting no risk of handling the TiO 2 anatase nanoparticles in their potentially hazardous powder form at any stage of our development. Low-price, easy-to-handle, and nontoxic materials were used. Therefore, our work represents an important contribution to the development of TiO 2 anatase nanoparticle coatings that provide a high photocatalytic effect and can thus be used for numerous applications.

Effect of Powder Calcination on the Cold Spray Titanium Dioxide Coating

“…The results indicated that low-temperature calcination can improve crystallinity and crystallite size of the as-synthesized TiO 2 powders. However, only a slight increase of crystallinity and crystallite sizes were observed for the powders calcined at 200 C, 300 C and 400 C. These results are in good agreement with previous reported studies which shows that only small changes in the crystallinity and the crystallite sizes of the TiO 2 powders were observed when the powders were calcined below 500 C 3,15) . Moreover, the XRD results were consistent with the DTA result as the curve also revealed that no temperature-induced phase transition occurred when the temperature was increased up to 400 C. Despite the fact that the transformation of anatase to rutile is above 700 C 12,15,16) and only anatase phase was identi ed even after the post-heat treatment.…”

“…These hard agglomerated particles, which have less porosity, were dif cult to fracture upon impact during the deposition as the particles were strongly bonded together. These strong bonds, which are formed by the crystalline bridges 3) between the particles, made them resistant to fragmentation and adherence on surface of the substrate. This result also shows that a further increase of post heat treatment temperature on as-synthesized TiO 2 powders; at 400 C and above lead to dif culties in building up the coating during collision, and this nding is in good agreement with previous study reported by Salim et al 12) .…”

“…This material has been used for a self-cleaning application on the external surfaces of buildings 2,3) . TiO 2 also known as road warrior as to clean the nitrogen oxide (NO x ) in the air that was produced by vehicles emissions 4) .…”

<p>Silver-Containing Titanium Dioxide Nanocapsules for Combating Multidrug-Resistant Bacteria</p>

“…While the surface charge measured for amorphous nanocapsules was negative, the anatase homologue unexpectedly showed a positive surface charge. Generally, the surface charge depends on the pH, 48 which was close to pH 7 as the Ag-TiO 2 formulations were dispersed in water. Interestingly, it has been shown that depending on the precursors used to generate titania, on the surfactant and on the heat treatment, the surface charge can indeed become positive even at pH 7.…”

Role of Platinum Deposited on TiO2in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

“…These properties make TiO 2 an attractive candidate for its utilization as a photocatalyst in the photocatalytic processes. TiO 2 has been extensively studied and demonstrated to be suitable for numerous applications such as, destruction of microorganisms [2][3][4][5], inactivation of cancer cells [6,7], protection of the skin from the sun [8][9][10][11], photocatalytic water splitting to produce hydrogen gas [12][13][14], manufacture of some drug types [15][16][17], degradation of toxic organic pollutants in water [18][19][20], and self-cleaning of glass and ceramic surfaces [21]. Even though TiO 2 is the most used semiconductor material, it exhibits some disadvantages, such as low surface area and fast recombination rate between the photogenerated charge carriers and the maximum absorption in the ultraviolet light region.…”