TiO2

TiO 2 is an effective and well-known photocatalyst for water and air purification, but its practical applications in visible light-assisted chemical reactions are hindered mainly by its poor visible light absorption capacity. Nitrogen-doped TiO 2 (N-doped TiO 2) has attracted considerable attention as a photocatalyst, and rapid progress has been made in enhancing the photocatalytic efficiency of TiO 2 under visible light irradiation. N-doped TiO 2 exhibits broad absorption in the visible region, which can allow the utilization of a large part of the solar spectrum. This might be useful for environmental and energy applications, such as the photocatalytic degradation of organic pollutants, solar cells, sensors, and water splitting reactions. This review focuses on the major developments in the synthesis of N-doped TiO 2 and its possible applications in the photocatalytic degradation of organic pollutants and environmental remediation under visible light irradiation.

Nano TiO2, one of the most effective photocatalysts, has extensive usein fields such as air purification, sweage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol (PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA cross-linking and that a large number of cavities have been generated on the surface and inside of porous PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15μm, which is consistent with that of CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than that of nonporous PVA-TiO2 hybrid hydrogel film.

The study examined the photodegradative efficiency of ZnO and TiO2 in degradation of antibiotics in aqueous matrices. Among several types of antibiotics, four antibiotics were chosen to feature the major classes of these compounds: amoxicillin, erythromycin, streptomycin and ciprofloxacin. Degradation of antibiotic solutions was carried out mainly under UV-light irradiation in a set time with the presence of small quantity of zinc oxide or titanium dioxide. Solutions were analyzed with HPLC chromatography and degradation percentages were calculated from ratio between pick area associated to no degraded drug solution and degraded drug solution’s pick area. Meanwhile, toxicity of antibiotics and degrading compounds were investigated using a biosensor system, consisting of Clark’s electrode associated with a portion of agar medium culture containing Saccharomyces Cerevisiae yeast cells. This way, it was possible to define the oxygen that was consumed by yeast cells. Toxicity associated to antibiotics and degrading products are related to decrease of oxygen concentration in solution. It is clear that zinc oxide is slower than titanium dioxide to degrade antibiotics, but zinc oxide shows better photodegradation efficiency than titanium dioxide in spite of its small specific superficial area.

Urea modified TiO 2 nanoparticles were synthesized at different TiO 2 : urea ratios (10, 30 and 60 (%wt) named UTiO 2-10, 30 and 60) by sol-gel method and annealing at 400 °C during 1 h. Characterization revealed the presence of TiO 2 nanoparticles with visible light absorption (between 400 and 500 nm) probably due by the formation of thermolysis urea byproducts such as melon, which may induce a TiO 2 /melon heterojunction. Then, modified nanoparticles were immobilized on chitosan films by adding 30% (70QS/30UTiO 2) and 50% 50QS/ 50UTiO 2) of UTiO 2 nanoparticles. Functionalized films were characterized by SEM-EDS, DRS and AFM. Photo-induced degradation of malachite green stains was evaluated on these films under different wavelengths. Upon UV-A + visible light irradiation, films showed good activity even slightly better than those containing Evonik P-25 (70QS/30P-25). Upon visible light between 450 and 800 nm, films evidenced a satisfactory performance but slower than under UV-A + visible light irradiation whereas the photobleaching activity of 70QS/30P-25 was very poor. When visible light irradiation with wavelengths higher than 590 nm was used, a slight photobleaching was also observed. DRS spectra taken at different irradiation times showed that dye underwent N-demethylated oxidative reactions either upon UV–vis or visible light irradiation. ATR-FTIR measurements revealed the generation of benzophenones after 6 h of irradiation probably suggesting the formation of singlet oxygen under visible light. 70QS/30UTiO 2-10 films showed a good photo-bleaching activity after 18 h of continuous UV-A + visible light irradiation.

— Textile effluent are abundant source of colored pollutant that present an enhancing the environmental danger. So the color present in textile effluent is that major concern of researcher today. Dyestuff present in textile effluent is mainly xenobiotic in nature and not easily self-biodegradable. Intensive treatment is necessary to degrade the dyestuff and reduces the COD and turbidity of textile effluent. The present work is an attempt to review the all possible treatment methods for remove dyestuff from textile effluent by Advanced Oxidation Processes (AOPs). The proposed studies in this paper summarize the capability and potential of conventional treatment for degradation of dyestuff from textile effluent. Conventional method for treatment of textile effluent has own certain limitations that can be well overcome by advance oxidation processes (AOPs).

Tungsten, silver and tungsten/silver co-doped titania nanopowders were synthesised via an aqueous sol–gel method. The size distribution and zeta potential of the starting sols were determined via photon correlation spectroscopy (PCS). The dried gels were thermally treated at two different temperatures, and the occurrence of amorphous phase was assessed using the combined Rietveld–RIR X-ray powder diffraction method. A systematic study of the optical properties of the powders was made with diffuse reflectance spectroscopy (DRS), and the energy band gaps were calculated using the differential reflectance method; while their morphology was investigated using electron microscopy analysis (TEM). The photocatalytic activity of the samples was assessed in liquid–solid phase, under UVA-light and visible-light irradiation, monitoring the degradation of an organic dye. The influence of the phase composition, optical properties, dimensions, and specific surface area of the powders on the photocatalytic activity was thoroughly discussed.

Titanium dioxide (TiO2) due to its high refractive index, is widely used in paint industry as a white pigment. In order to reduce this high cost of TiO2, a part of TiO2 is generally substituted by some other industrial mineral fillers such as calcite and calcined kaolin; however, this substitution affects the quality of paints in terms of stability, coverage (opacity), brightness (gloss), scrub resistance (film toughness), etc. In the present paper, precipitated calcium carbonate (PCC) was substituted for TiO2 in paint mixture at three different pigment volume concentrations (PVC). It was observed that substitution of TiO2 by PCC depends on PVC value at which there is an optimum PCC amount. The quality of paints produced by PCC along with its rheological properties was evaluated based on standard features in both wet and dry paints such as viscosity, density, opacity and gloss values. Addition of PCC increases the opacity to a certain point. Similarly, scrub resistance and viscosity increases with the addition of PCC at all PVCs, however, viscosity is not as much critical for the paint production. On the other hand, there is no any systematic effect of PCC on gloss value of the paint. This study overall demonstrates that PCC can be successfully used to substitute TiO2 only with a careful adjustment of PVC and other extenders used in the paint formulation.

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

Titanium dioxide (TiO2) is well established as one of the most common photocatalysts used for many environmental, anti-pollution and antibacterial applications. However, in this work, novel photocatalytic TiO2 nanopowders were modified with additions of 1 mol% copper, zinc or copper + zinc (with various Cu: Zn ratios). These were prepared via a green sol–gel route and thermally treated at 450 ºC. For the first time, a direct comparison of the effects of these two modifying agents was performed, both as single and co-substitution. The compounds were thoroughly characterised by means of advanced X-ray diffraction (Whole Powder Pattern Modelling, WPPM) and spectroscopic methods (Raman and UV–vis). For functional properties, the photocatalytic activity in the gas-solid phase (nitrous oxides (NOx) and isopropanol degradation (VOCs)) was tested under UV and visible light, and antibacterial activity against Gram positive and Gram negative bacterial strains was also investigated. Neither copper nor zinc entered into the TiO 2 structure, but nucleated as oxides at the surface of titania nanoparticles, thus creating a nano-heterojunction between the semiconductor materials; this also retarded the anatase-to-rutile phase transition. When comparing and contrasting their functional properties, it was found that Zn modification gave greater photocatalytic activity than that with Cu. On the contrary, for antibacterial activity, copper was shown to be a better additive. Co-modification with both metals did not improve the antibacterial behaviour, but did lead to an increase in photocatalytic activity in some cases.

Reduced graphene oxide sheets (RGO) with different number of graphene layers were used as platforms for TiO 2 nanoparticles deposited using hydrothermal process. The nanomaterials were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL) and diffuse reflectance UV–vis spectroscopy (DR-UV-vis). The photocatalytic activity of the nanocomposites was investigated in a model reaction of phenol decomposition under visible light irradiation. Here, the influence of graphene thickness on its photoactivity was explored. It was found that the highest photocatalytic activity was observed for the catalyst composed of single layer graphene and decreased when a number of graphene layers was higher. This might be related to the surface and electronic properties of reduced graphene oxide arising from different number of graphene layers and its interaction with titanium dioxide: (i) higher interfacial area of TiO 2-RGO with lower thickness of RGO, which could influence in enhanced transferring of photoinduced electron–hole pairs between TiO 2 and RGO, hence improving their separation ; (ii) variations in excitations lifetime relating to the diverse surface quality and density of trap sites of reduced graphene oxide; (iii) higher charge carriers mobility in 1-layer RGO compared to 2-and few-layers.

Fabrication and characterization of different natural dyes extracts of dye sensitized solar cell (DSSC) are reviewed in this paper. Inorganic metal complex, N3 dye is also studied as a comparison. The paper focussed on the performance of sensitization
which is related to the interaction between dye and TiO2 surface. The electrical performances of the cell such as short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF), and overall conversion efficiency (η) was also investigated via current-voltage characteristic measurement as well as light
absorption of dye loaded on TiO2 film. The resultant study showed that higher ratio of active compound and higher interaction of dye-TiO2 will results in higher conversion efficiencies.

An electrochemically active biofilm-assisted visible light active Ag@m-TiO2 photocatalyst was fabricated. The resulting nanocomposite was characterized by X-ray diffraction, transmission electron microscopy, diffuse absorbance/reflectance spectroscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy. The photocatalyst showed high photocatalytic activity and photoelectrochemical behavior due to the synergistic effect of the surface plasmon resonance (SPR) of Ag nanoparticles (AgNPs) and the induced defects in TiO2 (m-TiO2) nanoparticles. Ag@m-TiO2 nanocomposite showed much higher light harvesting ability because of the reduced band gap of m-TiO2 as well as the SPR characteristics of the AgNPs. The visible light photocatalytic experiments showed that the Ag@m-TiO2 nanocomposite possessed excellent photocatalytic activity for the degradation of methyl orange and methylene blue dyes under visible light irradiation compared to the Ag@p-TiO2 nanocomposite as well as p-TiO2 and m-TiO2 nanoparticles. Photoelectrochemical measurements, such as electrochemical impedance spectroscopy and linear scan voltammetry in the dark and under visible light irradiation, further supported the visible light active behavior of the Ag@m-TiO2 nanocomposite.

Rutile titanium oxide (TiO2) thin films require more energy to crystallize than the anatase phase of TiO2. It is a prime candidate for micro-optoelectronics and is usually obtained either by high substrate temperature, applying a substrate bias, pulsed gas flow to modify the pressure or ex-situ annealing. In the present work, we managed to obtain high enough energy at the substrate in order for the particles to form rutile TiO2 at room temperature without any intentional substrate bias
in a continuous gas flow. The rutile TiO2 thin films were deposited by a reactive radiofrequency magnetron sputtering system from a titanium target, in an argon/oxygen gas mixture. Investigations regarding the film’s structure and morphology were performed by X-ray diffraction (XRD), X-ray reflectivity (XRR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX), while the optical properties were investigated by means of ellipsometry.

Highly crystalline TiO2 nanostructures were prepared through a facile inorganic acid-assisted hydrothermal treatment of hexagonal-structured assemblies of nanocrystalline titiania templated by cetyltrimethylammonium bromide (Hex-ncTiO2/CTAB Nanoskeleton) as starting materials. All samples were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influence of hydrochloric acid concentration on the morphology, crystalline and the formation of the nanostructures were investigated. We found that the morphology and crystalline phase strongly depended on the hydrochloric acid concentrations. More importantly, crystalline phase was closely related to the morphology of TiO2 nanostructure. Nanoparticles were polycrystalline anatase phase, and aligned nanorods were single crystalline rutile phase. Possible formation mechanisms of TiO2 nanostructures with various crystalline phases and morphologies were proposed.

Nitrogen-doped TiO2 fibers (N–TiO2 Fs) were successfully and efficiently fabricated using titanium diisopropoxide bis(acetylacetonate) and polyvinylpyrrolidone (PVP) as a carrier polymer and nitrogen source via centrifugal spinning and subsequent calcination methods. XRD analysis confirmed that N–TiO2 Fs contains only anatase and rutile phases. XPS analysis revealed that N-atoms (from PVP) were successfully incorporated into the lattice of TiO2 whereas DTA and FTIR analysis confirmed that calcination at 550 °C for 1 h is appropriate to remove all organic impurities from the N–TiO2 Fs. SEM images showed that the N–TiO2 Fs of diameter (0.65 μm–1.2 μm) were produced and controlled with the amount of Ti-precursor. BET analysis confirmed that the addition of commercial TiO2 nanoparticles increased the specific surface area of the N–TiO2 Fs. UV–Vis diffuse reflectance measurements showed that N–TiO2 Fs exhibited a stronger light absorption in the visible region and a red-shift which is responsible for narrow band gap energy owing to the presence of N-atoms in the TiO2 lattice. This results in enhanced photocatalytic activity of the synthesized N–TiO2 Fs for degradation of methylene blue under visible light irradiation.

Development of a high surface area and efficient visible light induced photocatalyst on a large scale is a promising task from the practical perspective. In this study, visible light active C-doped anatase TiO2 multi-tubes were synthesized using banana (Musa acuminata) stem fiber as a sacrificial template, removed by calcination at 450 °C. During the calcination process, the lattice of anatase TiO2 phase was doped with C, and obtained multi-tubes showed high surface area (∼99 m2/g) with a mesoporous structure made of ∼15 ± 3 nm nanoparticles. The synthesized TiO2 multi-tubes showed an enhanced light absorption property in the whole visible light region and good thermal stability of the anatase phase up to 750 °C. The synthesized C-doped TiO2 multi-tubes manifest an excellent photocatalytic activity for the reduction of Cr (VI) to Cr(III) under the visible light exposure. This process may have lots of practical importance as the method of synthesis of the catalyst is novel and the multi-tubes structure can be synthesized on a large scale through a quick and economical way with excellent photocatalytic activity. This novel multi-tubes structure may also be useful for photovoltaics, antimicrobial, and Li-batteries applications in the future.

As populations grow, global energy consumption in the next 30 years is predicted to rise by nearly 50%. Nowadays and many years before, the most energy worldwide is provided by fossil fuel which leads to severe pollution and contributes to the greenhouse effect. Hydrogen is the most ideal alternative clean energy, but currently, there is no significant hydrogen production from renewable sources. Hence, there is an urgent need for the development of new photocatalysts which will allow a water splitting for hydrogen production. The photocatalytic water splitting using TiO2 offers a promising approach for clean, low-cost, and environmentally friendly production of hydrogen as a sustainable fuel. This paper reviews some recently used methods of synthesis such as hydrothermal, rapid breakdown anodization method, impregnation method, and sol-gel synthesis for the preparation of modified TiO2materials. These methods of synthesis provide the production of ultra-thin mesoporous TiO2 nanosheets, nanorods, and nanotubes as well as heterojunction structures. Some investigations show that introduction of Ti3+ atomic defects is beneficial for the photocatalytic water splitting for hydrogen generation. Some progress has been achieved by heterocoupling the two or more semiconductors. There is experimental evidence that in the presence of alcohol as a sacrificial agent, H2production rates decreased from a higher number of hydroxyl groups i.e. in order 3>2>1. The H2 generation is also larger when TiO2 is modified with the addition of small quantity of metal nanoparticles such as Pt, Pd, and Ni. One study has shown that the samples sensitised with Pt nanoparticles were superior to Pd and Ni modified TiO2, the other has shown that the co-catalyst activity followed the order Pd>Pt≈Au.

Urchin-like SnO 2 microspheres have been grown for use as photoanodes in dye-sensitized solar cells (DSSCs). We observed that a thin layer coating of TiO 2 on urchin-like SnO 2 microsphere photoanodes greatly enhanced dye loading capability and light scattering ability, and achieved comparable solar cell performance even at half the thickness of a typical nanocrystalline TiO 2 photoanode. In addition, this photoanode only required attaching ~55% of the amount of dye for efficient light harvesting compared to one based on nanocrystalline TiO 2. Longer decay of transient photovoltage and higher charge recombination resistance evidenced from electrochemical impedance spectroscopy of the devices based on TiO 2 coated urchin-like SnO 2 revealed slower recombination rates of electrons as a result of the thin blocking layer of TiO 2 coated on urchin-like SnO 2. TiO 2 coated urchin-like SnO 2 showed the highest value (76.1 ms) of electron lifetime (τ) compared to 2.4 ms for bare urchin-like SnO 2 and 14.9 ms for nanocrystalline TiO 2. TiO 2 coated SnO 2 showed greatly enhanced open circuit voltage (V oc), short-circuit current density (J sc) and fill factor (FF) leading to a four-fold increase in efficiency increase compared to bare SnO 2. Although TiO 2 coated urchin-like SnO 2 showed slightly lower cell efficiency than nanocrystalline TiO 2 , it only used a half thickness of photoanode and saved ~45% of the amount of dye for efficient light harvesting compared to normal nanocrystalline TiO 2 .

Although the Bi 2 S 3 QDs have an ideal bandgap for the efficient light absorbers, the Bi 2 S 3 QDs sensitised solar cells generally indicate low photovoltaic properties owing to the active photocorrosion of Bi 2 S 3 QDs. Herein, we report the enhancement of Bi 2 S 3 QDs sensitised solar cells using the co-sensitisation of Bi 2 S 3 with CdS QDs. By the homogeneous covering as well as effective blocking of photocorrosion and recombination, the CdS/Bi 2 S 3 co-sensitised solar cells showed threefold increase in efficiency.. (2016) 'Enhancing Bi 2 S 3 sensitised mesoporous TiO 2 solar cells by co-sensitisation with Bi 2 S 3 /CdS quantum dots',

Recent advances in nano-technology and nano-additives can give enhanced properties to natural hydraulic lime (NHL), creating a multifunctional material. We have prepared a novel nanocomposite, made of a commercial mortar with 1 wt% and 5 wt% added titania nanoparticles (NPs). These TiO2 NPs are themselves doped with 1 mol% silver, to give the material enhanced photocatalytic and antimicrobial properties. The Ag-doped TiO2 NPs were made from a simple, costs effective, aqueous green nanosynthesis process, and the end material only contains 0.01–0.05% Ag. As this mortar is intended to both combat atmospheric pollution, and create more durable/lower maintenance building façades (plastering and finishing) by limiting attack from microorganisms and pollutants, its photocatalytic anti-pollution activity under solar and visible (no UV) light for nitrous oxide (NOx) and volatile organic compound (VOC) removal was studied. The addition of dopants did not significantly alter the physical properties or curing of the mortar, while it showed excellent photocatalytic activity under sunlight, The mortars with only 1 and 5 wt% additives degraded 10.6% and 21% NOx after 45 mins, respectively, comparing well to a value of 50% for a pure TiO2/Ag+ sample. They also degraded VOCs under visible light, of the kind used for lighting inside buildings, with no UV component. As the NPs are contained in the whole of the mortar layer, not just as a coating, if the surface is chipped or damaged this mortar will not loose its photocatalytic capabilities.

Environmentally conscious biomorphic ceramics (Ecoceramics) are a new class of material manufactured from renewable resources and wastes. Sustainable cork wastes were pyrolysed, and this activated carbon template infiltrated with a sol-gel precursor (from aqueous green-chemistry) to form TiO 2 on heating in air, with the honeycomb microstructure of cork. Physical and optical band gap properties were characterised by XRD, SEM and Raman and UV-vis spectroscopy, and differences between alkaline and acidic activation of the carbon template also studied. With activation by HCl, HNO 3 or H 2 SO 4 , a mixture of anatase and rutile formed. NaOH activation resulted in pure anatase, but a large amount of Na was retained. At 1000 • C acid activated ecoceramics formed pure rutile, but the NaOH activated one formed Na 2 Ti 6 O 13 (sodium hexatitanate) as the major phase, coexisting with anatase, brookite and rutile. This material is worth further investigation, as Na 2 Ti 6 O 13 is reported as a photocatalyst in its own right.

Each oxidation process showed a different oxacillin degradation route. Photocatalysis and photo-Fenton mineralize, sonochemistry and electrochemistry not. Main pathways were hydrolysis, hydroxylation, sulfur oxidation and amide breakdown. a b s t r a c t This study evaluates the degradation of a selected b-lactam antibiotic (oxacillin) by TiO 2 photocatalysis, sonochemistry, the photo-Fenton process and electrochemistry (with a Ti/IrO 2 anode in sodium chloride). The four oxidation processes were able to successfully degrade the pollutant. Although in the three advanced oxidation processes the hydroxyl radical was involved in the degradation mechanism, significant differences with respect to the degradation pathways, by-products generated and degree of miner-alization were observed. In the electrochemical treatment, the main oxidation route was active chlorine attack, whereas for the sonochemical and photo-Fenton systems the hydroxyl radical played the determinant role. In TiO 2 photocatalysis, the combined action of direct oxidation by the holes and the attack of hydroxyl radicals removed the antibiotic. As a consequence, analysis of the by-products showed that all of the four oxidation processes exhibited thioether moiety oxidation, secondary amide breakdown and opening of the b-lactam ring. However, decarboxylation of the pollutant was only found with TiO 2 pho-tocatalysis, which can be explained by direct oxacillin oxidation by the holes. The oxacillin isomerization pathway was promoted using the electrochemical process. While the photo-Fenton and TiO 2 photocatal-ysis treatments also showed hydroxylation at the aromatic ring, due to the different degradation routes, the characteristics of the systems and the nature of the by-products generated, a different extent of min-eralization was found. The removal of total organic carbon in TiO 2 photocatalysis and the photo-Fenton system was $90% and $35% respectively, but with the sonochemical and electrochemical treatments the pollutant was not mineralized.

Density functional theory calculations were employed to model the electronic structure and the magnetic interactions in copper doped anatase and rutile titanium dioxide in order to shed light on the potential of these systems as magnetic oxides using different density functional schemes. In both polymorphs, copper dopant was found to be most stable in substitutional lattice positions. Ferromagnetism is predicted to be stable well above room temperature with long range interactions prevailing in the anatase phase while the rutile phase exhibits only short range superexchange interaction among nearest-neighbour Cu ions. Additionally, energetic evaluation of dopants in scattered and compact configurations reveals a dopant clustering tendency in anatase TiO2.

The past few years have witnessed remarkable progress in solution processed methyl ammonium lead halide (CH3NH3PbX3, X = halide) perovskite solar cells with reported photoconversion efficiency () exceeding 20% in laboratory scale devices and up to 13% in their large area modules (PSMs). These devices mostly employ mesoporous TiO2 nanoparticles as an electron transport layer (ETL) which furnishes a scaffold for the perovskite semiconductor to grow. However, limitations due to trap-limited electron transport and non-complete pore filling exist. Herein, we have employed TiO2 nanorods (NRs), a material offering a two-fold higher electronic mobility and higher pore-filing compared to their particle analogues, as an ETL. A crucial issue in NRs patterning over substrates is resolved using precise Nd:YVO4 laser ablation, and a champion device with  ~8.1% is reported via a simple and low cost vacuum-vapor assisted sequential processing (V-VASP) of CH3NH3PbI3 film. Our experiments showed a successful demonstration of NRs based PSMs via V-VASP technique which can be applied to fabricate large area modules with a pinhole-free, smooth and dense perovskite layer required to build high efficiency devices.

A B S T R A C T The influence of the addition of different doping agents (N, W and Hf) on the macroporous TiO 2 photoactivity toward the Rhodamine B degradation and ethanol photo-oxidation was evaluated. The samples were characterized by XRD, XPS, SEM, TEM, N 2 adsorption-desorption, UV–vis Diffuse Reflectance and Photoluminescence spectroscopies to study also the changes in the physico-chemical properties due to the presence of dopants. The photonic effect and the high ordered porous structure of the macroporous TiO 2 that lead to increase the path length of the light, were the key factors that allow to enhance the catalytic activity towards the dye and VOC degradation under visible and solar light irradiation of these materials compared to the commercial TiO 2 anatase. A significant improvement of the catalytic performances was achieved when the amount of the dopant was low, the ionic exchange of Ti 4+ ions by doping ions and the consequent substitution in the crystal lattice of TiO 2 was favoured, and/or the formation of non-stoichiometric Ti-compound on the TiO 2 surface was promoted.

TiO2 is a primary photocatalytic ingredient. If incorporated into building materials, it can keep surfaces clean and significantly reduce smog-forming air pollutants. Many researchers have focused on the ability of Nano TiO2 to reduce NOx emissions or other pollutants. However, developing countries are unable to widely utilize Nano materials due to cost and technology barriers, in spite of their great need to find means for protecting structures from pollution and improve air quality. Some studies proved that micro TiO2 (commercial grade) also has photocatalytic properties. However, the effect of this inclusion on key mechanical and durability properties needs to be verified before being recommended for wide use. In this research the effect of commercial grade TiO 2 powder on fresh state flow, compressive strength, shrinkage, sulfate resistance and carbonation. The results indicated that TiO2 decreased the workability as mortars became more sticky and dry with increased TiO2 content. The compressive strength was also reduced in TiO2 containing samples compared to the control samples especially at early ages. However, TiO2 powder as an additive in mortar was useful in reducing carbonation due to the filler effect. No samples in the current investigation showed signs of cracking or expansive mass loss due to sulfate exposure. It is recommended that TiO2 powder should be used as an additive to the mortar plaster to help in controlling the air pollution problem. However, some mix adjustment may be needed to counteract the loss in flow and strength due to the inclusion of TiO2 powder.

Epoxy resin blended with Unsaturated polyester resin and filled with TiO2 filler. ultrasonic mixing process. TiO2 nanoparticles were used as reinforcement in prepared by cast molding method with filler volume fractions (0%,1%, 2%, and 3%). The thermal conductivity constant, hardness, compression strength, wear, impact strength and DSC were studied. Compression strength, wear loss, thermal conductivity constant, DSC, FTIR, UV, atomic force were studied. The experimental results showed that the thermal conductivity constant decrease, hardness increase with filler content increase. Titanium dioxide content in epoxy/polyester blend matrix was dispersed and investigated by using ultrasonic technique .Sample four give the maximum value of compression strength. The glass transition temperature, melting point and degree of crystallization decrease by adding titanium dioxide.

Anatase phase of Titanium dioxide nanoparticles (TiO 2-nps) was prepared by new route using ultrasound assisted sol-gel method with operating conditions (40 kHz, 350 W). The crystal phase, morphology, surface area, thermal properties, and optical properties of TiO 2-npswere characterized by X-ray diffraction (XRD), FTIR spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), BET & BJH surface analysis, thermogravimetric analysis (TGA), and UV-Vis absorption spectroscopy. The synthesized nanoparticles have mesopores-micropores surface with pure anatase phase and small crystal size (approximately 11nm).The spherical shape of TiO 2-npscan be examined through the SEM, TEM, and AFM images. The synthesized TiO 2-nps have highly thermal stability (mass loss ≈ 0 until 542°C), the surface area and band gab values ofTiO 2-nps were calculated to be64.041 m 2 /g and 3.2 eV respectively.

Photocatalytic reduction with sunlight is an economical and promising advanced approach for reducing the excessive emissions of CO 2 from the combustion of fossil fuels. Aimed at practical applications, a type of inexpensive colored anatase material was used to evaluate CO 2 photoreduction performance on a platform with a continuous flow of gas mixtures (10 vol % CO 2 , 90% N 2), which resembles realistic flue gas conditions. The results showed an enhanced photocatalytic activity compared with standard P25 and significant improvement over pristine anatase. Based on a series of characterization techniques, we propose that the oxygen vacancies and surface hydroxyl groups on colored anatase can reduce the bandgap and assist the binding of CO 2 molecules. Our results showed that photoreduction of CO 2 is feasible under practical conditions, and the efficiency could be improved through modification of catalysts.

Au@TiO2 nanocomposites were used for the catalytic degradation of methyl orange and methylene blue by NaBH4. A detail pathway for step by step reduction, oxidation and complete mineralization of intermediates into the respective end-products was established by UV–vis spectroscopy, chemical oxygen demand, ion chromatography and cyclic voltammetry (CV). CV studies confirmed that the dyes were reduced and oxidized to the end-products by NaBH4 in the presence of Au@TiO2 nanocomposites and O2 radical, radical OH and HO2 radicals generated in situ. Results suggest that Au@TiO2 nanocomposites not only assist in the decolorization of dyes, but also promote their complete mineralization into harmless end-products.

A sol-gel method was used to produce thin films of the
anatase polymorph of titania on poly(ethylene Terephthalate)
(PET). This was done at a temperature of only 130°C, which
demonstrates the feasibility of the fabrication of flexible
photocatalyts, solar cells, and other semiconducting materials.
The films were ~570 nm thick and were comprised of grains of
15-25 nm diameter; these grains themselves consisted of
crystallites of 5-10 nm diameter

A novel approach was applied in order to fabricate multifunctional nanofiber mats. Titanium Oxide-Iron Oxide-Multiwall Carbon Nanotube (TiO2-Fe3O4-MWCNT) hybrid nanotubes were synthesized in chemical process for obtaining synergetic effect of dielectric, magnetic and conductive properties of TiO2, Fe3O4 and MWCNT respectively. Nanofiber mats of the TiO2-Fe3O4-MWCNT/PVDF with different ratios of the hybrid nanotubes (0, 1, 1.5 and 2 wt%) were produced using solution electrospinning method in order to obtain higher α to ß phase transformation and a porosity structure. Morphology, crystalline structures and α to ß phase transformation of the samples were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques. Also, the piezoelectric and electromagnetic wave absorption properties of nanofiber mats were investigated. Addition of the hybrid nanotubes into the PVDF promotes the crystallinity, α to ß phase transformation, piezoelectric and electromagnetic microwave absorption of the PVDF nanofibers. A fiber mat of the (TiO2-Fe3O4-MWCNT)2%/PVDF sample showed maximum piezoelectric sensitivity. Multilayer fiber mats of the (TiO2-Fe3O4-MWCNT)2%/ PVDF with low thickness (0.4 mm) showed significant maximum reflection loss (%85).

Nanostructured semiconducting metal oxides and particularly single nanowire devices offer exceptional gas sensitivity but at the expense of
statistical variations and excessive noise levels. In this study TiO2/poly(vinyl acetate) composite nanofiber mats were directly electrospun
onto interdigitated Pt electrode arrays, hot pressed at 120 °C, and calcined at 450 °C. This resulted in a novel multiple nanowire network
composed of sheaths of 200-500 nm diameter cores filled with readily gas accessible 10 nm thick single-crystal anatase fibrils. TiO2 nanofiber
sensors tested for NO2, in dry air, exhibited exceptional sensitivity showing with, for example, a 833% increase in sensor resistance when
exposed to 500 ppb NO2 at 300 °C, consistent with a detection limit estimated to be well below 1 ppb. Unusual response patterns were
observed at high NO2 concentrations (>12.5 ppm), consistent with n to p inversion of the surface-trap limited conduction facilitated by the
high surface-to-volume ratio of this material.

Titanium dioxide nanoparticles (TiO2-NPs) are common components used in sunscreens, cosmetics, industrial applications,
and many other products. Concerning their high production and widespread applications, characterization and quantification
of TiO2-NPs in various matrixes is a topic of great interest for researchers studying their potential environmental and
health impacts. Validated and easily applicable analytical tools are required to develop and implement regulatory frameworks and
an appropriate risk assessment for engineered nanoparticles (ENPs). Herein, we provide a critical review of the current knowledge
available on world-wide production and measured environmental concentrations as well as on available techniques to measure and
characterize these ENPs in the environment.

Thick anatase films were fabricated on graphite substrates using a method of anodic aqueous electrophoretic-deposition using oxalic acid as a dispersant. Thick films were subsequently fired in air and in nitrogen at a range of temperatures. The morphology and phase composition were assessed and the photocatalytic performance was examined by the inactivation of Escherichia coli in water. It was found that the transformation of anatase to rutile is enhanced by the presence of a graphite substrate through reduction effects. The use of a nitrogen atmosphere allows higher firing temperatures, results in less cracking of the films and yields superior bactericidal performance in comparison with firing in air. The beneficial effects of a nitrogen firing atmosphere on the photocatalytic performance of the material are likely to be a result of the diffusion of nitrogen and carbon into the TiO2 lattice and the consequent creation of new valence band states.

Sol-gel technique for the synthesis of anatase TiO2 at 420 C produces nanocrystals of 10-20 nm in size with Ti4+ in crystal volume and Ti3+ at terminal planes of the crystal. The study of Li+ co-doping effects on the structure, morphology, absorption, and luminescence of Eu3+ activated TiO2 anatase nanocrystals is presented. Pure anatase structure is achieved up to 9 at.% Li, with significant improvement in crystallinity of europium doped anatase TiO2. The Li þ co-doping reduces the unit cell volume of the crystal, induces the blue shift of the absorption edge, lengthens the lifetime of Eu3+ 5D0 excited state, and improves the Eu3+  emission intensity up to 37.5%. Judd-Ofelt analysis of Eu3+ emission showed enhancement of quantum efficiency from 66.4% to 98.7% when TiO2:Eu3+ was co-doped with 9 at.% of Li.

The activities of Cu/TiO2 prepared by a gamma-ray irradiation and Cu-doped TiO2 sample
prepared by a sol-gel method in photodegradation of methyl orange dye were examined.
Structural and properties of the solids investigated have been studied using XRD, TEM,
FTIR and BET techniques. The particles of the prepared TiO2 have high surface area and an
anatase phase structure. The remaining concentrations of 10 ppm MO at PH 1 reaches 0.13
and 2.25 ppm after 120 min under UV irradiation using 0.15g/L of Cu/TiO2 and Cu-TiO2
catalysts, respectively.