Different Types Of TiO2 Research Articles

Effect of TiO2 on Acidity and Dispersion of H3PW12O40 in Bifunctional Cu-ZnO(Al)-H3PW12O40/TiO2 Catalysts for Direct Dimethyl Ether Synthesis

The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with a Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. In this work, different types of TiO2 were used as a support to study the effect of changes in the structure of the TiO2 support on the acidity and dispersion of HPW. Various TiO2 supports with different structural and surface characteristics have been studied and the results indicate that: (i) the crystallinity and crystallite size of the primary particles of the HPW units depend on the TiO2 support; (ii) the pore size distribution of the TiO2 support affects the surface segregation of the heteropolyacids; and (iii) changes in the supported HPW acid catalysts do not significantly alter the crystal structure of the CuO and ZnO phases after contact with CZA in bifunctional catalysts. The activity results indicate that the variation in the intrinsic activity of the Cu-ZnOx centers in the bifunctional catalysts for direct DME synthesis is minimal due to the limited alteration of the crystal structure of the centers.

Rational designing of TiO2-X@Cs3Bi2X9 nanocomposite for boosted hydrogen evolution

Halide perovskites are known as compounds possessing interesting properties, including visible light-induced photoactivity, however, they suffer from instability. Herein, a novel technique for reducing the decomposition rate of halide bismuth-based perovskites Cs3Bi2X9 (X=I, Br, Cl) in the aqueous environment by combining with different types of TiO2 (anatase TiO2-I, anatase/rutile TiO2-B, and rutile TiO2-C synthesized using HI, HBr, and HCl acids, respectively) has been described. The specific type of HX has a notable impact on the crystallinity, morphology, and photocatalytic abilities of TiO2-X and they constitute a reaction environment that allows perovskites to survive the synthesis of TiO2. Studies reveal that TiO2-I is the optimal support material for immobilizing perovskite nanoparticles, owing to its extensive surface area and the synergistic effect it has with Cs3Bi2I9. Adding a small amount of Cs3Bi2I9 to iodine-doped TiO2-I improved the photocatalytic performance in the aqueous environment. As a result, 24.3, 22.5, 22.0, and 13.5-fold improvement in H2 production has been realized with decreasing amounts of Cs3Bi2I9 perovskite (10, 50, 100, and 300 mg). Upon detailed characterization and analysis of photocatalytic properties, it has been suggested that when Cs3Bi2I9 nanoparticles are dispersed within the TiO2-I structure, they can establish a close connection which allows the photogenerated electrons of TiO2-I to be extracted to Cs3Bi2I9, effectively preventing the charge recombination. This study provides a feasible possibility for the photocatalytic application of perovskite-based nanocomposites in the aqueous environment.

Enhancing oxygen evolution reaction performance in PEM water electrolyzers through support pore structure optimization

The widespread application of PEMWE is limited because of the challenges associated with the oxygen evolution reaction (OER) catalysts, including the need for catalysts with both high activity and stability. In this study, three different types of TiO2 with different pore structures were used as supports for Ir-based oxygen evolution reaction (OER) catalysts. Among the investigated supports, TiO2 support with low surface area and macropores (TiO2-MC) was found to be the most effective support for the iridium catalyst (Ir/TiO2-MC). Such a catalytic enhancement mainly comes from inter-connected mesoporous structure of iridium induced by macropores of TiO2 support. The entangled iridium particles with mesopores in Ir/TiO2-MC have higher electrochemically active surface area and higher number of Ir(III), resulting in increased OER activity. On the other hand, the other two types support (TiO2-MS and TiO2-P25) with higher surface areas produced isolated iridium nanoparticles dispersed on the surface of TiO2 support, resulting in the lower OER activities. Ir/TiO2-MC showed remarkable performance in PEMWE (1.75 A/cm2 @ 1.8 V) with a low iridium loading of 0.27 mgIr/cm2 which is even higher performance than two types of commercial catalysts. Ir/TiO2-MC showed the best durability in half cell and it is also stable in PEMWE single cell for 72 h. The stability of Ir/TiO2-MC is attributed to the presence of Ir(IV) species and having the mesoporous structure that is beneficial for mass transport. The proposed Ir/TiO2-MC catalyst with its high activity and stability has the potential to contribute to the development of cost-effective PEMWE.

In Vitro Safety Assessment of In-House Synthesized Titanium Dioxide Nanoparticles: Impact of Washing and Temperature Conditions.

Titanium dioxide nanoparticles (TiO2 NPs) have been widely used in food, cosmetics, and biomedical research. However, human safety following exposure to TiO2 NPs remains to be fully understood. The aim of this study was to evaluate the in vitro safety and toxicity of TiO2 NPs synthesized via the Stöber method under different washing and temperature conditions. TiO2 NPs were characterized by their size, shape, surface charge, surface area, crystalline pattern, and band gap. Biological studies were conducted on phagocytic (RAW 264.7) and non-phagocytic (HEK-239) cells. Results showed that washing amorphous as-prepared TiO2 NPs (T1) with ethanol while applying heat at 550 °C (T2) resulted in a reduction in the surface area and charge compared to washing with water (T3) or a higher temperature (800 °C) (T4) and influenced the formation of crystalline structures with the anatase phase in T2 and T3 and rutile/anatase mixture in T4. Biological and toxicological responses varied among TiO2 NPs. T1 was associated with significant cellular internalization and toxicity in both cell types compared to other TiO2 NPs. Furthermore, the formation of the crystalline structure induced toxicity independent of other physicochemical properties. Compared with anatase, the rutile phase (T4) reduced cellular internalization and toxicity. However, comparable levels of reactive oxygen species were generated following exposure to the different types of TiO2, indicating that toxicity is partially driven via non-oxidative pathways. TiO2 NPs were able to trigger an inflammatory response, with varying trends among the two tested cell types. Together, the findings emphasize the importance of standardizing engineered nanomaterial synthesis conditions and evaluating the associated biological and toxicological consequences arising from changes in synthesis conditions.

Recent development on titania-based nanomaterial for photocatalytic CO2 reduction: A review

Since the past few decades, nanomaterials proved to be an interesting candidate towards several applicative purposes. The oxide-based semiconductor nanomaterials provide added benefit for their capability in the utilization of renewable sources of energy, i.e., light energy. In this context, TiO 2 -based nanomaterials are extremely promising candidate and has been widely studied. As per the current global scenario humankind is majorly dependent on fossil fuels as the prime energy asset. This created two key challenges: (i) crisis of fossil fuel and (ii) global warming owing to increased level of atmospheric carbon dioxide (CO 2 ). In consideration of this, photocatalytic CO 2 reduction to fuels and value-added-chemicals, is one of the revolutionary approaches to resolve both problems efficaciously. To address this concern efficiently, modified TiO 2 based photocatalyst has been explored by several research groups worldwide, owing to their interesting physicochemical properties. This review summarizes fundamental aspects (principle, thermodynamics, kinetics), structural and compositional engineering of TiO 2 based photocatalyst to achieve efficient photocatalytic CO 2 reduction. Moreover, this article provides an elaborate study on several factors associated; along with the documentation of their efficiency and selectivity to assess the benchmark towards CO 2 photoreduction reactions. Furthermore, an overview has been presented regarding photocatalytic CO 2 reduction mechanism for different types of TiO 2 based photocatalyst supported by computational studies. Finally, perspective related to probable modification approaches and opportunities in this vital area of research, has been discussed.

Evaluation of rheological properties of mortar with TiO2 addition

Abstract Adding TiO2 tocoating mortars is carried out to promote self-cleaning through photocatalytic activity. However, this addition influences the workability of the mortar and, consequently, the application stage as the TiO2 used can present a large number of fine particles and a high surface area, increasing the demand for mixing water, requiring consistency adjustments before coating. In this work, three mortars (two with the addition of different types of TiO2 and one reference) were developed on a laboratory scale to maintain similar workability, using the flow table test. The amount of kneading water was changed to maintain a spread of 220 ± 10 mm and the content of air-entrained was kept constant, around 25%. The mortars were evaluated using the squeeze flow method. Then, a blind test was performed to assess the mason sensitivity during handling and application of the coating, and all mortars were considered similar. However, the yield of the compositions with TiO2 addition was lower compared to the reference composition, making it possible to explain the results based on the physical parameters of the formulations and with a more in-depth analysis of the rheological indices obtained by the squeeze flow test.

Antimicrobial silicone rubbers based on photocatalytically active additives

AbstractThe modification of plastics to generate germ‐reducing surface materials is a promising strategy to decrease nosocomial infections in hygiene‐sensitive areas. In this paper, photocatalytically active nanoparticles were incorporated as additives, not as a coating, into silicone rubber matrix material to produce elastic antibacterial bulk materials. Samples with 5 wt% and 10 wt% of two different types of TiO2 and ZnO were prepared and investigated. The thermal analysis of the developed materials showed a complete vulcanization of the developed materials and slight modifications of mechanical properties were found. Investigations of the surface of the materials indicated no changes in the wettability of the surfaces or in their fourier transform infrared spectrometer (FT‐IR) spectra, suggesting no degradation of the developed material. The photocatalytic activity on the surface of the test samples was investigated by microbial tests with Escherichia coli, Pseudomonas fluorescens, and Staphylococcus aureus bacteria. Depending on the additive type and the test germs, the samples showed different intensities of a germ‐reducing effect (up to >99,999%).

A spectroscopic study for the photocatalytic oxidation of propane over different types of TiO2

ABSTRACT The photocatalytic selective oxidation of propane was investigated by in-situ Fourier transform infrared spectroscopy under the illumination of UV light. Two different commercially available TiO2 photocatalysts were applied; UV-100 and P25. The characterisation data showed significant differences between the two samples; such as phase composition, texture properties, -OH surface density, and the presence of contaminations. P25 (the mixed rutile-anatase phases) showed better adsorption for the reagents and even small quantity of products were observed in dark. However, UV-100; the pure anatase phase with high surface area, exhibited 3–4 times higher photocatalytic activity than P25. Moreover, it was observed that on a similar propane conversion level, the selectivity % of acetone was almost four times higher over P25 than UV-100. Finally, upon mixing UV-100 with rutile, it was observed that the acetone selectivity was improved extensively.

Thermal stability of Al2O3/TiO2 stacks for boron emitter passivation on n-type silicon solar cells

Boron-diffused samples passivated by Al2O3/TiO2 stacks with different types of TiO2 were investigated. An emitter saturation current density of 11 × 10−15 A/cm2 was obtained for Al2O3/TiO2 passivated samples with symmetrical 100 Ω/sq. boron diffusion. The surface passivation of Al2O3/TiO2 stacks was strongly impacted by the temperature, gas, and sequence during two-step annealing. In addition, the saturation current density of the Al2O3/TiO2 stacks is influenced by the TiO2 layers with an O3 treatment. Enhanced passivation performance of the Al2O3/TiO2 stacks was achieved by a combination of appropriate TiO2 capping layer and post-annealing. The results of this study provide reliable criteria for the design of thermally-stable Al2O3/TiO2 stacks on high-efficiency silicon solar cells.

TiO2 synthesized by various routes and its role on environmental remediation and alternate energy production

Researchers debate on if it is only the crystalline properties of TiO2 or also the surface morphology and even optical properties of different types of TiO2 are the instrumental parameters on photocatalysis. It is a subject of exploration whether the phase pure anatase TiO2 or the heterojunctions and band alignment in the two polymorphs of TiO2(anatase and rutile) plays the determining role in efficacy of a photocatalytic reaction. Three different synthetic routes such as polymerizable sol–gel, solution combustion and customized microwave assisted hydrothermal method have been employed to synthesize TiO2. The materials are characterized systematically using XRD, FE-SEM, HR-TEM, diffuse reflectance, photoluminescence, BET surface area and Raman spectroscopy. It is found that TiO2 synthesized by polymerizable sol–gel approach yields a mixed phase of anatase and rutile, while the other two approaches yield phase pure anatase. The band gap obtained from diffuse reflectance measurements are compared with the direct and indirect band gaps derived from Kubelka–Munk plots. Among the three synthetic routes, TiO2 synthesized by customized microwave assisted hydrothermal method exhibits the highest surface area, pore volume and diameter, and lowest recombination, which in turn play a crucial role in high rate of photocatalytic degradation of methylene blue. On the other hand, the phase pure anatase made out of solution combustion route with moderate surface area, pore volume and diameter outperformed the rest two catalysts in photocatalytic hydrogen production. The different reaction specific photocatalytic efficacies of these two materials are discussed with respect to the combinatorial role of nano-crystallinity, surface properties, and optical properties.

Enhanced photo-degradation of bisphenol pollutants onto gold-modified photocatalysts

Here we report a comparative study of Au supported on different types of TiO2 in the photocatalytic degradation of BPA. The beneficial presence of a small amount of rutile was proven once again, the TiO2 anatase showing a lower activity despite a higher surface area. Also, the role of gold plasmon was evidenced by the use of an inert silica support.

Utilization of waste glass in translucent and photocatalytic concrete

This article addresses the development of a translucent and air purifying concrete containing waste glass. The concrete composition was optimized applying the modified Andreasen & Andersen model to obtain a densely packed system of granular ingredients. Both untreated (unwashed) and washed waste glass fractions were utilized in concrete. The fresh and hardened concrete properties were investigated. In order to ensure a durable material, the expansion due to the alkali-silica reaction was also analyzed. Subsequently, concrete tiles of different thicknesses were produced and their translucency was quantified. Additionally, two different types of TiO2 were utilized in concrete to analyze the glass aggregates effect on the photocatalytic degradation of air pollutants (NO and NO2). The obtained results indicate that the developed concrete has satisfactory mechanical properties, coupled with good durability, translucency and enhanced air purification properties.

Application of TiO2 to amperometric NOx sensors based on NASICON

The work focused on improvement of the current response to NO and the reduction of response time of both NO and NO2. By adding a layer of TiO2 catalyst layer, the shortcoming of NO insensitivity of traditional NASICON based amperometric NO2 sensor was solved. TiO2 was known as an n-type semiconductor and a high-performance NO oxidation catalyst. We separately applied different types of TiO2 (rutile and Degussa P25) on the device and compared the test results with the traditional type without a catalyst layer. The results showed that the TiO2 attached device exhibited a significant improvement to NO response, and P25 was better than rutile TiO2 on account of the higher activity of anatase TiO2. In addition, TiO2 also played a role of a semiconductor electrode, resulting in the increase of response to NO2. The response time of NO and NO2 was separately shrunk from 153s, 70s to 77s, 43s owing to the P25 layer. The current responses were found to be barely affected by the coexistence of CO2.

Self-cleaning acrylic water-based white paint modified with different types of TiO2 nanoparticles

Purpose – This paper aims to study the Improvements in self-cleaning property of the white acrylic water-based paint by addition of different percentages of three commercially available titanium dioxide (TiO2) nanoparticles as additives. Then, due to the risk of destruction of polymeric materials in the presence of nanoparticles, degradation of dry paint film samples was investigated for 15 days using two important chalking and yellowing factors. Finally, the TiO2-modified paint sample with the best performance and optimum percentage of TiO2 nanoparticles that produced desired self-cleaning and dry film properties was introduced. Design/methodology/approach – Self-cleaning and dry film properties of white acrylic water-based paint were investigated by addition of three various types of commercial available TiO2 nanoparticles (SSP-25, STA-100 and KA-100). X-ray diffraction, transmission electron microscopy and Brunauer–Emmett–Teller were used for characterization of TiO2 samples. Colorimetric tests in decolourization of C.I. Basic Red 46 (BR46) were used for determination of self-cleaning properties of TiO2-modified paints in comparison with unmodified paint sample. Also, paints defects such as chalking and yellowing were tested along two weeks. Findings – The results indicated that, in all types of TiO2 nanoparticles, by increasing the amount of TiO2 in modified paint, self-cleaning property of the samples was enhanced. The paint containing SSP-25 indicated better self-cleaning properties than others due to its larger surface area. However, its usage above 3.5 weight per cent caused yellowing and chalking defects in dried paint film. Practical implications – In this research, TiO2-modified paint sample with the best performance in both self-cleaning and mechanical properties was selected among the nine sets of prepared paint samples. All the materials used in this research such as acrylic resin and three types of TiO2 nanoparticles are of industrial grade. Therefore, the introduced TiO2-modified paint sample has the potential for the commercial production as a building exterior paint. Originality/value – In the present study, an attempt at introducing a self-cleaning paint sample with acceptable mechanical properties using three types of commercially available TiO2 nanoparticles as additives and industrial grade of acrylic resin which is the most commonly used water-based resin in building paints, as binder. As far as it was searched in the literatures, the parallel study of the self-cleaning and mechanical properties of paints has not been reported as noteworthy. Self-cleaning property of the acrylic water-based paint samples was investigated by adding three types of the commercially available TiO2 nanoparticles. Also considering the possible detrimental effects of TiO2 nanoparticles on polymeric materials and consequently on physical properties of the paint, chalking and yellowing factors in dried paint samples were evaluated.

Catalytic oxidation of trichloroethylene over TiO2 supported ruthenium catalysts

Different types of TiO2 (anatase, P25 and rutile) supported ruthenium catalysts were synthesized by wet impregnation and directly reduced in H2. The distribution characteristics of ruthenium species were thoroughly studied before and after trichloroethylene oxidation. The results show that ruthenium oxide species are very unstable in the anatase phase, but quite stable in the rutile phase of TiO2. This phenomenon results in different catalytic behaviors for the Ru/TiO2 catalysts. The Ru/TiO2 (P25) catalyst has the best catalytic performance among these catalysts. The complete conversion temperature of trichloroethylene is in the temperature range of 260–270°C.

TiO2–SiO2 films from organic-free colloidal TiO2 anatase nanoparticles as photocatalyst for removal of volatile organic compounds from indoor air

Different types of TiO2–SiO2 composites in the form of powder or films have been reported as efficient photocatalysts for decomposition of organic compounds in liquid and gas phase. Herein, we report for the first time on the formation of efficient TiO2–SiO2 films made from acidic organic-free colloidal solution of TiO2 anatase nanoparticles (AS) and mesoporous SiO2 (SBA-15) with 100% loading (TiO2: SiO2 molar ratio 1:1) under simple and low cost procedure. AS was prepared from metatitanic acid precursor using a novel, environmentally friendly approach of TiO2 nanoparticles precipitation with NaOH and peptization with HCl. These AS/SBA-15 films, immobilized by brush deposition on glass carriers, showed total decomposition of toluene and 91% decomposition of formaldehyde as model VOCs in gas phase, at room temperature under UVA irradiation in lab-made batch photoreactor. The trend of photocatalytic efficiency for decomposition of formaldehyde was AS/SBA-15>P25>PC500>AS. The adsorption capability of the AS/SBA-15 was higher in comparison to its pure TiO2 analogues (AS, P25, PC500) in case of toluene. Turnover frequency (TOF) of the AS/SBA-15 was approximately six times higher in comparison to its pure TiO2 analogue AS for toluene and formaldehyde. The potential of AS/SBA-15 for the use in air cleaning devices is finally discussed.

Study of TiO<sub>2</sub> Energy Gap Based Temperature Annealing for High Performance Solar Cells

This paper describes the TiO2 performance based energy gap related to its annealing process. TiO2 is one of the comprehensive band gap semiconductor materials which has been under extensive investigation in recently. This is due to its application in various fields such as photo electrolysis, photo catalysis, dye sensitized solar cells, gas sensor, optical fibers etc. Furthermore, advent of nanotechnology increases its applications many fold and different types of TiO2 have been used for different types of sensing applications. The TiO2 exists in different crystalline forms such as anatase, rutile and brookite. Solar cells consists of mono-crystalline, thin films, dye sensitized solar cells and multi-junction. TiO2 can be produced by using techniques like sputtering, vacuum evaporation, pulse laser deposition, molecular beam epitaxial, sol-gel and chemical bath deposition. Successful annealing process leads to a high performance solar cells. To fabricate the solar cells, there are four types of ways which are doctor blading, spin coat, sol-gel and screen printing. A comparison of annealing process, nanoscale structure and performance output powers been done successfully. The produced TiO2 also been tested with a high power performance.

Effect of toluene, an immiscible pollutant, on the photocatalytic degradation of azo dye

An adverse effect of a water-immiscible pollutant, toluene, on the photocatalytic degradation of Direct Red 80 (DR80) with TiO2 in an aqueous solution was observed when toluene was added as a continuous free layer. However, a more efficient photocatalytic system was obtained when toluene was added in the Pickering emulsion (PE) form with TiO2. With only UV and two different types of TiO2 (more hydrophilic and large-sized type A TiO2 and less hydrophilic and small-sized type B TiO2), 44% and 59% color removal was observed, respectively. Almost 20% decrease in color removal with toluene in the continuous free layer form was observed, however, the higher color removal was obtained when toluene was added as PE stabilized with type B TiO2 than with type A TiO2. The higher color removal was owing to the good stability of PE stabilized with type B TiO2.

Thermal decomposition approach for the synthesis of CdS–TiO2 nanocomposites and their catalytic activity towards degradation of rhodamine B and reduction of Cr(VI)

CdS–TiO2 nanocomposites were prepared by a simple thermal decomposition approach. The effect of using four different types of TiO2 (as-prepared sol–gel TiO2 nanoparticles, sol–gel TiO2 after calcination at 500°C, sol–gel TiO2 after calcination at 700°C and macro-crystalline TiO2 ) on the structure, optical properties and photocatalytic activity of the nanocomposites was investigated. The nanocomposites were characterized by powder X-ray diffraction, field emission scanning electron microscopy coupled with energy dispersive X-ray analysis, transmission electron microscopy, diffuse reflectance spectroscopy and photoluminescence spectroscopy. The CdS–TiO2 nanocomposites consist of cubic CdS and anatase TiO2 nanocrystallites when as-prepared sol–gel TiO2 nanoparticles, sol–gel TiO2 calcined at 500°C and macro-crystalline TiO2 were used. On the other hand, when sol–gel TiO2 after calcination at 700°C was used, the nanocomposites were found to consist of rutile TiO2. TEM results indicate uniform distribution of CdS nanoparticles (10.5±1.6nm) on the TiO2 matrix in the nanocomposites prepared using as-prepared sol–gel TiO2 nanoparticles and sol–gel TiO2 after calcination at 500°C. In the nanocomposites, a blue shift of the band gap of CdS compared to bulk CdS is observed. The CdS–TiO2 nanocomposites act as good catalyst for the photodegradation of rhodamine B (RhB) and reduction of Cr(VI) in the presence of sunlight.

Factors affecting the selectivity of the photocatalytic conversion of nitroaromatic compounds over TiO2 to valuable nitrogen-containing organic compounds

The photocatalytic conversion of various nitroaromatic compounds in alcohols employing four different types of TiO(2) (Sachtleben Hombikat UV100 as anatase, Crystal Global R34 as rutile, Evonik-Degussa Aeroxide P25 as an anatase-rutile mixture, and home-made mesoporous anatase) has been studied. The effect of platinization of these different types of TiO(2) on the reaction sequence has also been investigated. Upon irradiation of an ethanolic solution of m-nitrotoluene, as a model reaction, in the presence of the bare photocatalyst, different products were obtained according to the applied photocatalyst. It was found that the surface properties of the photocatalyst play an important role in the reaction pathway and thus in the selectivity of the products. In all cases, a simultaneous reduction of the nitro compound and an oxidation of the alcohol are induced by the photogenerated electrons and holes, respectively. An imine is then produced upon condensation of the generated aldehyde and amino compounds. Rutile was found to be more selective towards the primary amino compound (m-toluedine) while anatase catalysts gave a mixture of m-toluidine and its imine (N-ethylidene-3-methylaniline). A cyclization reaction of the produced imine to generate methyl quinoline was observed when Aeroxide P25 was used as a photocatalyst. Employing platinized TiO(2), the hydrogenation of the produced imine yielding N-alkylated products was found to occur in all cases. However, the selectivity towards the mono N-alkylated product was the best using platinized Hombikat UV100. This selectivity was found to be also influenced by the loaded amount of Pt, the platinization method, and the illumination time but not by the light intensity.