Thin layer photocatalysts of TiO2-Ag composites

Abstract

BORBÁLA TEGZE a , EMŐKE ALBERT a , BOGLÁRKA DIKÓ a , JÁNOS MADARÁSZ b , GYÖRGY SÁFRÁN c , ZOLTÁN HÓRVÖLGYI a, * ABSTRACT. Mesoporous TiO2 coatings were prepared by sol-gel dipcoating method on glass and SiO2 coated glass substrates. They were modified with silver by two different methods: impregnation of as-prepared coatings in AgNO3 aqueous solution; coating deposition from precursor sols containing AgNO3. Transmittance spectra, refractive index, layer thickness and porosity were determined by UV-Vis spectroscopy. Crystallinity of the samples was characterized by XRD, and the morphology and structure by HR-TEM. Photoinduced wettability conversion of the samples was studied, and it was found that the presence of the SiO2 barrier layer and the silver content had significant effect on the wetting behaviour. The photoactivity and reusability of the samples were investigated with methyl orange dye degradation under ultraviolet (UV) irradiation. TiO2 coatings impregnated in 1M AgNO3 solution were found to be the most stable photocatalyst system.

Effect of Silver Modification on the Photoactivity of Titania Coatings with Different Pore Structures

“…Indirect band gap was assumed, and the determined band gap energy was found to be similar for c-TiO 2 and p-TiO 2 samples (3.39 and 3.38 eV, respectively), while the Ag modified coatings had a slightly lower band gap energy (3.34 eV for p-TiO 2 (1Ag) and 3.33 eV p-TiO 2 -Ag coatings). This suggests that TiO 2 is present mainly in its anatase crystal phase in these samples, in accordance with the results of our previous publication [25], in which XRD measurements were carried out on model powder samples of the c-TiO 2 , c-TiO 2 (1M), c-TiO 2 (0.03M) and p-TiO 2 -Ag type coatings, and where it was found that anatase phase is present in 90-100 wt %, while rutile phase is present in 0-10 wt %, and the crystallite size was determined to be~12 nm.…”

“…The simplest and most often used way to prepare TiO 2 -Ag composites with this method is to add AgNO 3 (or other precursor containing silver ions) to the precursor sol [21][22][23]. Another promising possibility is to modify the as-prepared mesoporous coatings by impregnation in AgNO 3 solution, followed by post-treatments step(s) in which the silver ions are reduced [24][25][26][27]. These post-treatment steps most often include heat treatment [24,25] or UV irradiation [26,27].…”

“…Another promising possibility is to modify the as-prepared mesoporous coatings by impregnation in AgNO 3 solution, followed by post-treatments step(s) in which the silver ions are reduced [ 24 , 25 , 26 , 27 ]. These post-treatment steps most often include heat treatment [ 24 , 25 ] or UV irradiation [ 26 , 27 ]. Some further examples of less often used methods for silver modification include using a microemulsion system [ 28 ], and electrochemical deposition [ 29 ].…”

Obtaining and Characterizing 3D Printable Polymer Based Composites with BaTiO3 Filler

“…In this context, the development of the composite materials with specific characteristics for the most diverse applications is in the continuous attention of the scientific community and industrial developers [3]. Thus, developments of ceramic composites [4] for various medical applications [5,6], electrodes for electrochemical synthesis [7], thin layers for photocatalysis [8], polymer-based composites with various fillers [9 -16] are reported with uses including the electrical engineering field [17][18][19][20], etc.…”