SiO2/TiO2 Antireflective Coatings With Photocatalytic Properties Prepared by Sol–Gel for Solar Glass Covers

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
G. San Vicente ◽  
A. Morales ◽  
N. Germán ◽  
S. Suarez ◽  
B. Sánchez
Keyword(s):  
Organic Molecules ◽  
Sol Gel ◽  
The Self ◽  
Antireflective Coatings ◽  
Solar Systems ◽  
Coated Glass ◽  
Solar Plant ◽  
Self Cleaning ◽  
Promising Development ◽  
Plant Efficiency

The glass covers of solar systems are usually coated with antireflective (AR) coatings on both sides that allow to increase the efficiency of the whole system. At the same time, the accumulation of dust and dirt particles on the surface of the AR coated glass decreases the transmittance of the covers, even to values lower than the uncoated glass. This decrease in the cover transmittance reduces the solar radiation that reaches the absorber and, in this way, a decrease in the solar plant efficiency would be obtained. So, the use of films that combine high transmittance and self-cleaning capacity seems to be a promising development. This paper reports the preparation of sol–gel porous TiO2 and SiO2 bilayers on borosilicate glass. The porosity and thickness of both layers have been optimized in order to obtain the optimal photocatalytic and optical properties. Solar transmittance values of 0.964 were obtained for the TiO2/SiO2 coated glass. The highest value of transmittance reached is 0.993 and it is placed at 600 nm. The self-cleaning properties were evaluated using methylene blue and trichloroethylene (TCE) as model organic molecules using UV-A light. The results showed that the SiO2/TiO2 samples degraded the colorant faster than the SiO2 sample. Moreover, the degradation of TCE in air in a continuous fix bed photoreactor for samples with different TiO2 film thicknesses was also performed. The TCE conversion was found dependent on the TiO2 thickness. Nevertheless, the increase in the thickness of this layer reduced transmittance properties. The study demonstrates that it is possible to combine antireflective and self-cleaning properties in the same material.

scholarly journals Sol-Gel Coatings for Subaquatic Self-Cleaning Windows

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 375
Author(s):  
Andrew I. M. Greer ◽  
David Moodie ◽  
Graham Kerr ◽  
Nikolaj Gadegaard
Keyword(s):  
North Sea ◽  
Marine Bacteria ◽  
Optical Transmission ◽  
Sol Gel ◽  
Optical Devices ◽  
The Self ◽  
Worst Case ◽  
Airborne Pollutants ◽  
Cleaning Performance ◽  
Self Cleaning

Self-cleaning windows are well known for their ability to function with airborne pollutants, but there is a growing industry for semi-permanent subaquatic optical devices, where the performance of such windows should be considered. Here sol-gel technology is explored as a means of producing self-cleaning, subaquatic, sapphire windows. We demonstrate removal of marine bacteria and, in the worst-case contamination scenario, dead North Sea crude oil (API 35). This greasy contaminant was smeared across the windows to effectively reduce optical transmission strength to just 54%. The titania-based sol-gel-coated windows can restore transmission to within 10% of the clean value in less than one day, unlike standard sapphire windows, which lose 68% transmission following contamination and aquatic submergence over the same duration. A range of theories to enhance the self-cleaning performance of the sol-gel coating were explored, but none of the tested variables were able to provide any enhancement for subaquatic performance.

Self-cleaning treatment on historical stone surface via titanium dioxide nanocoatings

2019 ◽  
Vol 48 (5) ◽  
pp. 404-408
Author(s):  
Pooneh Kardar ◽  
Reza Amini
Keyword(s):  
Titanium Dioxide ◽  
Sol Gel ◽  
The Self ◽  
Architectural Heritage ◽  
Content Type ◽  
Smart Coatings ◽  
Self Cleaning ◽  
Reported Data ◽  
Inductive Property ◽  
Practical Implications

Purpose The purpose of this study is to evaluate the possibility of using titanium dioxide coating in the field of architectural heritage. Design/methodology/approach In this research, a titanium dioxide coating was prepared and then applied to the travertine stone surfaces. The nature of the coating was determined through various observations and analyses. Moreover, the effect of photocatalytic self-cleaning was evaluated using an organic dye (Rhodamine B). Findings The results of XRD, DLS and SEM confirmed the formation of small anatase crystals. The hydrophilic behavior on the surface was observed by coatings based on titanium dioxide. Research limitations/implications The self-cleaning ability of titanium dioxide is due to the synergistic effect of its optical inductive property, which is activated with sunlight. Practical implications The self-cleaning coatings are interested for many industries. The reported data can be used by the formulators working in the research and development departments. Social implications Self-cleaning systems are considered as smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications. Originality/value The application of titanium dioxide coating in the field of architectural heritage is a great challenge. Therefore, in this research, a titanium dioxide coating was prepared by sol-gel method and then applied on travertine surfaces and its properties were studied.

scholarly journals Synthesis and photocatalytic activity for TiO2 nanoparticles as air purification

2018 ◽  
Vol 162 ◽  
pp. 05006 ◽  
Author(s):  
Adawiya Haider ◽  
Riyad Al-Anbari ◽  
Ghadah Kadhim ◽  
Zainab Jameel
Keyword(s):  
Contact Angle ◽  
Titanium Dioxide ◽  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Xrd Analysis ◽  
The Self ◽  
Root Mean Square Roughness ◽  
Bacterial Inactivation ◽  
Water Contact ◽  
Self Cleaning

In the present work, titanium dioxide (TiO2) nanoparticles (NP’s) were prepared using sol-gel process from Titanium Tetrachloride (TiCl4) as a precursor with calcinations at two temperatures (500 and 900) °C. The effect of calcinations temperatures on the structural, optical, morphological and Root Mean Square (roughness) properties were investigated by means of Scanning Electron Microscopy, X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM). Bacterial inactivation was evaluated using TiO2-coated Petri dishes. A thin layer of photocatalytic TiO2 powder was deposited on glass substrate in order to investigate the self-cleaning effect of TiO2 nanoparticles in indoor and outdoor applications. Ultra-hydrophilicity was assessed by measuring the contact angle and it evaluated photolysis properties through the degradation of potassium permanganate (KMnO4) under direct sunlight. XRD analysis indicated that the structure of TiO2 was anatase at 500 °C and rutile at 900 °C calcination temperatures. As the calcination temperature increases, the crystallinity is improved and the crystallite size becomes larger. Coated films of TiO2 made the has permeability, low water contact angle and good optical activity. These are properties essential for the application of the surface of the self-cleaning. The final results illustrate that titanium dioxide can be used in the build materials to produce coated surfaces in order to minimize air pollutants that are placed in microbiologically sensitive circumference like hospitals and the food factory.

scholarly journals Preparation of mechanically stable triple-layer interference broadband antireflective coatings with self-cleaning property by sol–gel technique

RSC Advances ◽  
2017 ◽  
Vol 7 (24) ◽  
pp. 14660-14668 ◽  
Author(s):  
Yuanyang Li ◽  
Ke Yang ◽  
Bibo Xia ◽  
Bowen Yang ◽  
Lianghong Yan ◽  
...  
Keyword(s):  
Sol Gel ◽  
Antireflective Coatings ◽  
Gel Method ◽  
Sol Gel Method ◽  
Triple Layer ◽  
Gel Technique ◽  
Self Cleaning

Mechanically stable broadband antireflective coatings with self-cleaning property were fabricatedviasol–gel method.

Preparation and Characterization of Novel Self-Cleaning Glasses with TiO2 Coatings

2012 ◽  
Vol 573-574 ◽  
pp. 135-139 ◽  
Author(s):  
Yu Mian Liu ◽  
Wei Ping Hu
Keyword(s):  
Environmental Protection ◽  
Ultraviolet Light ◽  
Sol Gel ◽  
The Self ◽  
Formaldehyde Concentration ◽  
Ultraviolet Light Irradiation ◽  
Foundation Base ◽  
Self Cleaning ◽  
Almost All ◽  
Organic Gases

Common glass for architecture had only one function, i.e., transparency and the requirement for indoor health made “environmental protection type” novel glass necessary. In the present study, a novel self-cleaning glass was prepared by sol-gel method. To form self-cleaning glass, common glass was adopted as the foundation base and TiO2 coatings were cover its outside surfaces. The novel glass had little change in shape but alteration to slightly white compared to common glass, thanks to white TiO2. The self-cleaning glass could reduce formaldehyde concentration of air from more than 160 mg•m3 to 0.4 mg•m3 within 60 h, while the common glass could cut down to ca. 30 mg•m3 and reaching equilibrium before 24 h. The removal of formaldehyde by common glass could be owing to adsorption action and slightly gradation by ultraviolet light, and the removal by self-cleaning glass could be mostly assigned to photodegradation by TiO2 when ultraviolet light irradiation. Besides, the self-cleaning glass exhibit 74.99% and 91.60% anti-bacteria rate to Escherichia coli and Staphylococcus aureus, respectively, when common glass was chosen as control. In brief, the self-cleaning glass was proved excellent to remove formaldehyde and inhibit bacteria. As a result of the non-preference of the photodegradtion and anti-bacteria by TiO2, it was believed the self-cleaning glass could remove almost all the kinds of indoor organic gases and inhibit almost all the kinds of bacteria, including some pathogens. The self-cleaning glass had great potential in interior finish application meeting the challenge for environmental protection.

Self-Cleaning Test of Doped Anatase-Coated Glass Plates

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Jorge Medina-Valtierra ◽  
Silvia Janneth Campos-Reyna ◽  
Claudio Frausto-Reyes ◽  
Sergio Calixto ◽  
Jorge Ramírez-Ortíz
Keyword(s):  
Degradation Products ◽  
Window Glass ◽  
Irradiation Time ◽  
Glass Plate ◽  
The Self ◽  
Polycyclic Aromatic Compound ◽  
Coated Glass ◽  
Intermediate Products ◽  
Self Cleaning ◽  
Free Glass

Doped anatase thin films on glass were deposited by ultra-spinning from titanium isopropoxide-based sol-gels. To test the self-cleaning properties of anatase-coated glass, crystalline fluoranthene, a polycyclic aromatic compound, was sprayed over the glass and then irradiated using a 365 nm UV source. This anthropogenic contaminant was removed until 98 wt.% at 140 h of irradiation time with the 2 wt.% zinc ferrite-doped anatase film. The fluoranthene proportion degraded on anatase-free glass was much lower than with anatase coating giving only 12% for an irradiation time of 140 h. In this form, the coated-glass transparency was recovered almost totally at this irradiation time for the doped anatase film mentioned, which did not occur with anatase-free glass, even after more than 400 h of UV irradiation. A correlation was found between the total weight losses of the solid compound and the intensity of the Raman vibration at 671 cm-1 during photocatalytic degradation. After 140 h of irradiation, while the presence of fluoranthene is not detected by Raman spectroscopy, glass plate presented ultra-thin zones of degradation products. Thus, the removal of these intermediate products deposited on glass was directly measured by means of weight difference. The self-cleaning properties of doped anatase coating on window glass could have a positive influence on outdoor and indoor air quality. In this work, degradation mechanisms and intermediate products were not discussed or identified.

Super-Hydrophilic Lu3+-Doped TiO2 Photocatalysts for Self-Cleaning Applications

2012 ◽  
Vol 512-515 ◽  
pp. 1700-1703
Author(s):  
Wen Yuan Xu ◽  
Li Na Meng ◽  
Chuo Yang ◽  
Guo Lin Huang
Keyword(s):  
Sol Gel ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
The Self ◽  
Photocatalytic Properties ◽  
Long Time ◽  
Ft Ir ◽  
Self Cleaning ◽  
Composition Structure ◽  
And Performance

The self-cleaning glasses can be realized by coating the photoinduced super-hydrophilic Lu3+-doped TiO2 thin films via innovative ultrasonic-sol-gel route. The composition, structure and performance of the as-obtained material were characterized by XRD, SEM, FT-IR and UV-vis. The super-hydrophilicity is assessed by contact angle measurement. Photocatalytic properties of these films are evaluated by degradation of methyl orange under UV irradiation. The results indicate that the crystalline phase composition of Lu3+ doped TiO2 films is anatase, and the particle size is from 6 to 15 nm. In addition, Lu3+ doping can bring the red shift of the optical absorption edge of TiO2. The films exhibit excellent super-hydrophilicity and photocatalytic properties after UV radiation and the hydrophilicity can maintain for a long time in the dark place, which favors greatly the self-cleaning function of the films.

scholarly journals Influence of the Addition of TiO2 Nanoparticles on the Self-Cleaning Performance of Cementitious Composite Surfaces

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 42
Author(s):  
Elvira Grebenișan ◽  
Andreea Hegyi ◽  
Henriette Szilagyi ◽  
Adrian-Victor Lăzărescu ◽  
Brăduț Alexandru Ionescu
Keyword(s):  
Tio2 Nanoparticles ◽  
Organic Molecules ◽  
The Self ◽  
Matrix Degradation ◽  
Cementitious Composite ◽  
Duration Of Action ◽  
Cementitious Matrix ◽  
Cleaning Performance ◽  
The Matrix ◽  
Self Cleaning

The presence of TiO2 nanoparticles in a cementitious matrix induces self-cleaning capacity in the presence of UV radiation by combining two mechanisms: surface hydrophilicity and degradation of the stain agent molecules. Experimental results indicate an increase in surface water absorption and, indirectly, in the degree of hydrophilicity, with the increase in the concentration of TiO2 nanoparticles in the matrix. Degradation of organic molecules, rhodamine B, is dependent on the duration of action and intensity of UV rays and the concentration of nanoparticles in the cementitious matrix. An addition of 3–6% TiO2 is effective and sufficient for a good self-cleaning capacity of cementitious surfaces.

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