Download or read book Synthesis of Ag doped TiO2 Nanoparticles by Combining Laser Decomposition of Titanium Isopropoxide and Ablation of Ag for Dye sensitized Solar Cells written by Ahmed Kamal Al-Kamal and published by . This book was released on 2015 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured powders of TiO2 and Ag-doped TiO2 are synthesized by a novel pulsed-laser process that combines laser ablation of a silver (Ag) disc with laser decomposition of a titanium tetra-isopropoxide (TTIP) solution. Nanoparticles are formed by rapid condensation of vaporized species in the plasma plume generated by the high power laser, resulting in the formation of rapidly quenched Ag-doped TiO2 nanoparticles that have far-from-equilibrium or metastable structures. The uniqueness of the new ablation process is that it is a one-step process, in contrast to the two-step process developed by previous researchers in the field. Moreover, its ability to synthesize an extended-solid solution phase of Ag in TiO2 may also be unique. The present work implies that other oxide phases, such as Al2O3, MgO and MgAl2O4, can be doped with normally insoluble metals, such as Pt and Ir, thus opening new opportunities for catalytic applications. Again, there is the prospect of being able to synthesize nanopowders of diamond, cBN, and mixtures thereof, which are of interest for applications in machine tools, rock-drill bits, and lightweight armor. A wet-chemistry method is also investigated, which has much in common with that adopted by previous workers in the field. However, photo-voltaic properties do not measure up to expectations based on published data. A possible explanation is that the selected Ag concentrations are too high, so that recombination of holes and electrons occurs via a quantum-tunneling mechanism reduces photo-activity. Future work, therefore, will investigate lower concentrations of Ag dopant in TiO2, while also examining the effects of metastable states, including extended solid solution, amorphous, and semi-crystalline structures.
Download or read book Titanium Dioxide written by Magdalena Janus and published by BoD – Books on Demand. This book was released on 2017-07-26 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium dioxide is mainly used as a pigment and photocatalyst. It is possible to find it in food, cosmetics, building materials, electric devices, and others. This book contains chapters about characteristics of anatase and rutile crystallographic structure of titanium dioxide and the use of theoretical calculation for photoactivity determination.
Download or read book Nanostructured Titanium Dioxide in Photocatalysis written by It-Meng Low and published by CRC Press. This book was released on 2021-06-18 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium dioxide (TiO2) has drawn considerable attention as an attractive inorganic raw material for various applications due to its inexpensiveness, nontoxic nature, stability, and excellent photocatalytic activity. Photocatalysis is one of the most promising route for sustainable chemistry of the 21st century. It can contribute to solving environmental, global energy, and chemical problems, as well as to the sustainable production of commodities in the near future. This book presents the fundamentals of photocatalysis in nanostructured TiO2 and describes the factors affecting the photocatalytic activity, design, and synthesis of various forms of nanostructured TiO2. It highlights the use of ion-doping and inert-atmosphere annealing to extend the light-absorption range of photocatalysts and reduce recombination between electrons and holes. It discusses numerous applications in the fields of energy and environment, such as water purification, gas sensing, storage and delivery, and energy generation. The book is an invaluable resource and useful guide for a broad readership in various fields of catalysis, materials science, environment, and energy.
Download or read book Updates on Titanium Dioxide written by Bochra Bejaoui and published by BoD – Books on Demand. This book was released on 2023-08-30 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium dioxide (TiO2) has received a lot of attention due to its inexpensive cost, benign nature, and great photocatalytic potential. TiO2 has numerous applications, including in photocatalysts, Li-ion batteries, solar cells, and medical research. However, its performance is unsatisfactory due to a variety of issues, including a wide band gap (3.01 to 3.2 eV) and quick electron–hole pair recombination (1012 to 1011 s). Many efforts have been made to improve the qualities of TiO2, such as structural and dopant changes, which expand its applications. This book focuses on the properties of TiO2-modified nanoparticles, including their synthesis, alterations, and applications.
Download or read book Picosecond Laser Generation and Modification of Ag TiO2 Nanoparticles for Antibacterial Application written by Abubaker Hamad and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Titanium Dioxide written by Dongfang Yang and published by BoD – Books on Demand. This book was released on 2018-06-27 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium dioxide is currently being used in many industrial products. It provides unique photocatalytic properties for water splitting and purification, bacterial inactivation, and organics degradation. It has also been widely used as the photoanode for dye-sensitized solar cells and coatings for self-cleaning surfaces, biomedical implants, and nanomedicine. This book covers various aspects of titanium dioxide nanomaterials including their unique one-dimensional, two-dimensional, mesoporous, and hierarchical nanostructures and their synthetic methods such as sol-gel, hydrothermal, anodic oxidation, and electrophoretic deposition, as well as its key applications in environmental and energy sectors. Through these 24 chapters written by experts from the international scientific community, readers will have access to a comprehensive overview of the recent research and development findings on the titanium dioxide nanomaterials.
Download or read book Flame Synthesis of Tungsten doped Titanium Dioxide Nanoparticles written by Yuqian Zhang and published by . This book was released on 2016 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-doped titanium dioxide nanoparticles can be employed in various applications, including dye-sensitized solar cells and gas sensors. Metal-doping is able to enhance the performance of titanium dioxide as photocatalysts by the dispersion of metal ions into the TiO2 matrix. In this work, tungsten-doped titanium dioxide nanoparticles are synthesized by a multiple diffusion flames burner using TTIP as the precursor (for titania) and tungsten mesh as the metal source (for doping). This novel method of using a metal mesh as precursor for doping is especially advantageous for low-vapor-pressure precursors and the entire nanoparticle synthesis process to be gas-phase based. The effect of varying the tungsten loading rate is studied for synthesizing doped titanium dioxide with different tungsten amount. The results show that high loading rate of tungsten can trigger homogenous nucleation of WO3 prior to reaching the TTIP precursor loaded region, thereby leaving less tungsten ions to be doped into TiO2, when compared to the relatively lower tungsten loading rate configuration. Heat treatment at 973 K in an Ar atmosphere moves some of the tungsten out of the TiO2 structure, thus making a new WOx-TiO2 solid solution, while tungsten ions are reduced to lower oxidation states. Moreover the annealing process also increases the unit cell volume of W-doped TiO2, making the value closer to that of the un-doped TiO2. XRD, SEM, TEM, and XPS results are to prove the theory presented. UV Vis results show tungsten doping and heat treatment improve the absorbing ability of titanium dioxide in the visible light wavelength range significantly.
Download or read book Titanium Dioxide Nanoparticles written by Yucheng Lan and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past few decades, titanium dioxide has been an important material for different sectors of modern technology. More precisely, this ceramic has been synthesised in the form of nanomaterial and applied in buildings, dye-sensitised solar cells, hydrogen production, sensors, rechargeable batteries, electrocatalysis, self-cleaning, environmental pollution, and antibacterial actions based on its enhanced optical properties. This book describes preparation, photocatalytic properties, and applications of nanostructured titanium dioxide with a particular focus on non-traditional syntheses and brookite. Titanium oxide nanoparticles are produced by hydrothermal processes, ionic liquid-assisted reactions, biological approaches, ball-milling techniques, etc. Physical properties and potential future applications of the produced nanostructured titanium dioxide nanoparticles are reviewed. Toxicity of titanium oxide nanoparticles and titanium oxide nanowires are also discussed.
Download or read book Synthesis of TiO2 based nanoparticles for photocatalytic applications written by Kranthi Kumar Akurati and published by Cuvillier Verlag. This book was released on 2008-10-27 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various gas phase synthesis routes have been employed to produce TiO2 based nanoparticles for photocatalytic applications. Synthesis routes have been selected depending up on the feasibility/constraints of the particular process to produce a given kind of material. The first attempt at producing the photocatalysts involved the synthesis of pure TiO2 nanoparticles by a flame aerosol process. The growth behaviour of TiO2 particles which has significant influence on their crystallinity and surface area, has been controlled by varying the process parameters and selecting suitable flame configurations. An existing method to determine the crystallinity of the powder has been modified which facilitates comparison of the degree of crystallinity of the nanoparticles synthesized by various methods. Resultant TiO2 nanoparticles were characterized by X-ray diffraction (XRD) and nitrogen physisorption to determine the degree of crystallinity quantitatively and surface area, respectively, and the decomposition rate of an industrial dye, methylene blue, has been taken as the measure of the photocatalytic activity (PCA). The importance of an optimum combination of crystallinity and surface area for improved PCA has been shown by comparing the PCA of the as-synthesized nanoparticles with commercial TiO2 (Degussa P25). By depositing another semiconductor material on TiO2, PCA of the resultant composite photocatalyst can be improved due to the effective separation of the charge carriers. The deposited semiconductor has been chosen by virtue of its conduction band potential which should be higher than that of the TiO2. Accordingly, SnO2/TiO2 composite nanoparticles have been synthesized in a single-step by feeding evaporated precursor mixtures into an atmospheric pressure diffusion flame. For the lowest concentration (3.4 mol %) of SnO2 employed in this study anatase phase of TiO2 is stabilized, while segregation of SnO2 is seen at medium (6.9 to 12.4 mol %) and high concentrations (20.3 mol %). Though the equilibrium phase diagram predicts complete solubility of one oxide in another at all compositions, segregation of SnO2 phase is observed which is explained by the usage of diffusion flame in the present study. A particle formation mechanism of SnO2/TiO2 composites is proposed based on the single component aerosol formation. Photocatalytic activity of the composite particles is tested for the degradation of methylene blue and is compared with pure TiO2 synthesized under similar conditions. Improved photocatalytic activity of the composite particles is attributed to the stabilized anatase phase and better charge separation due to the coupling of TiO2 and SnO2 within the composite nanoparticles. The adsorption properties of the SnO2/TiO2 particles are similar to the pure TiO2 particles and the PCA can be further improved coupling the advantages of adsorption properties and charge carrier separation in a single system. WO3 is the kind of semiconductor material that has suitable conduction band potential and surface acidity to perform the dual function mentioned above. Due to the non-availability of the suitable volatile precursor for WO3, WO3/TiO2 composite nanoparticles have been synthesized by using flame spray synthesis. W and Ti precursors were dissolved in a suitable solvent and sprayed into the high temperature acetylene flame using an atomizing gas. Particles with controlled W:Ti ratios were produced at various flow rates of precursor solution and the resulting powders were characterized by BET (Brunauer-Emmett-Teller) surface area analysis, XRD, TEM (Transmission electron microscopy), Raman and ATR-IR (Attenuated total reflection infrared) spectroscopy. Two-dimensional coordinatively unsaturated wolframyl species were well dispersed on the TiO2 surface for the samples equal to or less than 3.6 mol% WO3 and contributed to increase the surface acidity. Crystalline WO3 was formed for the samples above 3.6 mol% WO3. The formation of crystalline WO3 is attributed to the enhanced rate of condensation of W species with increasing loading of tungsten. The variation of lambda (defined as the ratio of the actual oxygen-to-fuel ratio of the reactants to the stoichiometric fuel-to-oxygen ratio) affects the type of surface species dispersed on TiO2 particles and thereby the resultant acidity. The improved photocatalytic activity of the composite particles is attributed to the increased surface acidity and better charge separation due to the coupling of WOx species and TiO2 within the composite nanoparticles. The development of a practical photocatalytic system focuses on the cost effectiveness of the process. The usage of the expensive solar concentrators and artificial ultraviolet (UV) irradiation for photocatalytic reactions has negative influences on the cost effectiveness. In addition to the cost effectiveness resulting from using solar energy, abundance of the visible light (55 % compared to 6 % of UV) motivates to synthesize TiO2 nanoparticles that absorb visible light. Nitrogen doped TiO2 nanoparticles that absorbs visible light have been synthesized by hot-wall reactor synthesis. The extent of doping of nitrogen is controlled by varying the hot-wall reactor temperature and the flow rate of the gaseous reactants. Increasing the nitrogen concentration above a certain value reduces the PCA and is attributed to the formation of Ti3+ that act as recombination centre for the charge carriers. The concentration of nitrogen at which significant Ti3+ formation takes place has been systematically investigated by XPS (X-ray photoelectron spectroscopy) measurements.
Download or read book Synthesis and Characterization of Nitrogen doped Titanium Oxide Nanoparticles for Visible light Photocatalytic Wastewater Treatment written by Mohammad Ali Pelaschi and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: TiO2 nanoparticles are one of the most suitable materials for photocatalysis, specifically for water and air treatment and removal of a wide variety of organic pollutants such as dyes, aromatic compounds, and chlorinated aromatic compounds. Methods of synthesis of TiO2 are generally categorized in two main classes of wet chemical, and dry methods. Wet chemical methods generally provide a better control over size, size distribution, and shape; all of which significantly affect photocatalytic performance of the produced nanoparticles. Despite its advantages over other semiconductor photocatalysts, wide band-gap of titania restrains its photocatalytic activity to only UV light, which only makes up to 5% of the light reaching surface of the earth. To induce visible-light activity, titania has been doped by different dopants, including transition metal-dopants such as Fe, and Co and non-metal dopants such as N, and C. Nitrogen has been shown to be a better dopant, providing a suitably placed energy state within the band-gap of TiO2, and not suffering from issues related to transition-metal dopants such as low thermal and physical stability and high electron-hole recombination rates. To dope titania with nitrogen, one could add the nitrogen source together with other precursors during synthesis, referred to as wet chemical doping methods, or anneal the synthesized titania nanoparticles under a flow of ammonia at high temperatures, referred to as dry doping methods. While different doping methods have been studied individually, the author maintains that there has been an absence of research comparing the effectiveness of these methods, on photocatalytic performance of N-doped TiO2 within a consistent experiment. In this research TiO2 nanoparticles were synthesized by a facile, inexpensive sol-gel method, and doping was done by wet chemical methods, dry methods, and a combination of both these methods. Visible-light photocatalytic activity of these nanoparticles was evaluated by their efficiency in degradation of methyl orange. The results show wet doping methods increase the efficiency of titania nanoparticles more than dry doping, or combination of both. Further investigation showed that the main reason for higher activity of wet chemically doped nanoparticles is due to their higher available surface area of 131.7 m2.g-1. After normalizing the available surface area, measured by the BET method, it was shown that a combination of wet chemical doping, and dry doping at 600 °C result in the most active nanoparticles, but high temperature dry doping severely decreases the surface area, lowering the overall efficiency of the product. Additionally, N-doped TiO2 nanoparticles were synthesized using a simple hydrothermal method, in which the nitrogen source was used not only to dope, but also to control shape, size, size distribution, and morphology of the titania nanoparticles, and to induce aqueous colloidal stability. It was shown that addition of triethylamine during the synthesis, results in ultra-small, colloidally stable, cubic TiO2 nanoparticles, while using triethanolamine results in formation of TiO2 pallets, assembled into spherical, rose-like structures. The synthesized nanoparticles show impressive efficiency in visible-light removal of phenol, 4-chlorophenol, and pentachlorophenol, achieving 100% degradation of a 100-ppm phenol solution in 90 min, more than 98% degradation of a 20-ppm 4-chlorophenol solution in 90 min, and 97% degradation of a 10-ppm pentachlorophenol in 180 min with 500 ppm loading of the catalyst in all cases. Moreover, synthesized nanoparticles showed no sign of deactivation after 5 consecutive runs, removing 4-chlorophenol, showing their reusability.
Download or read book Chemically Deposited Nanocrystalline Metal Oxide Thin Films written by Fabian I. Ezema and published by Springer Nature. This book was released on 2021-06-26 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book guides beginners in the areas of thin film preparation, characterization, and device making, while providing insight into these areas for experts. As chemically deposited metal oxides are currently gaining attention in development of devices such as solar cells, supercapacitors, batteries, sensors, etc., the book illustrates how the chemical deposition route is emerging as a relatively inexpensive, simple, and convenient solution for large area deposition. The advancement in the nanostructured materials for the development of devices is fully discussed.
Download or read book Novel Soft Chemistry Synthesis of Titanium Dioxide for Applications in Dye Sensitized Solar Cells and Photocatalysis written by Aiat Hegazy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the high cost of solar cells prevents them being a primary candidate for energy production, great attention has been paid towards them because of the depletion of the conventional energy sources-fossil fuels-and the global warming effect, and the need to provide power to remote communities disconnected from the power grid. To reduce the cost, thin film technologies for silicon solar cells have also been investigated and commercialized, but dye sensitized solar cells (DSSC) have been considered as a promising alternative even for the silicon thin films with efficiency exceeding 10%. Compared with silicon-based photovoltaic devices, DSSCs are quite complex systems that require an intimate interaction among components. Within the last few years, conclusive smart solutions have been provided to improve the efficiency of these cells, with solar efficiency that makes them potential competitors against silicon devices. The most successful systems use titanium oxide as a core material tuned to collect and transmit the electrons generated by the photo-excitation of dye molecules. However, most of the solutions demonstrated so far require a thermal treatment of the TiO2 photoelectrodes at temperatures that preclude using any flexible organic substrate. This treatment prevents development of any roll-to-roll manufacturing process, which would be the only way to achieve cost effective large scale production. In order to overcome this major drawback, a novel synthesis of TiO2 at room temperature is described in the present document. This synthesis leads to 4-6 nm nanocrystalline anatase, the desired phase of titanium oxide for photoactive applications. An intensive study was carried out to explore the properties of these nanoparticles, via a mixture design study designed to analyze the influence of the starting composition on the final TiO2 structure. The influence of a post-synthesis thermal treatment was also explored. This 4 nm nanocrystalline TiO2 exhibits a high specific surface area and a good porosity that fulfills the requirements for an efficient photoanode; a high surface area allows high dye loading, and, hence, increases photocurrent and photo-conversion efficiency. Another important result of this study is the band gap, as it confirmed that nanocrystalline anatase has an indirect band gap and a quantum confinement for a crystal size of less than 10 nm. This result, well-known for bulk materials, had been discussed in some previous publications that claimed the effectiveness of a direct band gap. Following this synthesis and the structural and spectroscopic analyzes carried out in parallel, photocatalytic study was an important tool to further explore the semiconducting properties of this material. Additionally, our material gave very promising results in photocatalytic dye degradation, compared to the commercial products, even if it was not initially synthesized for this application. We assign these performances to the improved crystallinity resulting from thermal activation, without changing the crystal size, and to the ability to optimize the surface. This photocatalytic study gave us insights into the methods that optimize the electronic structure of the titanium oxide. Hence, we decided to thermally activate the nanoparticles before the preparation of films to be inserted into DSSCs. At this stage, as the thermal activation applies to the powder, the resulting material can still be used with flexible substrates. We have successfully integrated these nanoparticles in dye sensitized solar cells. Various organic additives were added to the TiO2 paste used to prepare photoelectrode films, to increase the porosity of the film and have a crack-free film with good attachment to the substrate. We demonstrated that the dye was chemically attached to the TiO2 surface, which led to better electron transport. Different treatment methods (UV and thermal) were applied to the film to cure it from organic additives and improve the electronic connectivity between the particles. When the UV treatment was applied as a single method, i.e. without thermal treatment, the cell performance was lower, but a combination of thermal treatment and UV enhanced this performance. We compared our nanoparticles to the reference material used in most of the studies on DSSC, that is, TiO2 Degussa, with cells prepared the same way. Our nanoparticles revealed higher overall conversion efficiency. As the dye attachment to the TiO2 surface is an important parameter that enhances the cell efficiency, so we checked via ATR-FTIR how the dye attached to the TiO2 surface. In addition, FTIR, UV-Vis, and IV measurements revealed that the amount of dye adsorbed was increased through HCl treatment of the photoelectrode. We also checked the internal resistance of the cell using impedance spectroscopy, and the analysis proved a successful integration of the nanoparticles in dye-sensitized solar cells as there was an increase in both the electron life time and the recombination resistance, and a decrease in the charge transfer resistance compared to the commercial powder.
Download or read book Multifunctional Photocatalytic Substrates and Textiles Constructed Via Layer by Layer Self assembly of Ag and TiO2 Nanoparticles written by Marvin Motay and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: TiO2 and Ag nanoparticle multilayered films were constructed on model substrates and textiles via Layer-by-Layer (LbL) assembly. The TiO2 nanoparticle based films constructed on model substrates showed a non-conventional photocatalytic behaviour for gas phase formic acid mineralisation upon UV-A irradiation, and a high mineralisation was obtained for a single layer TiO2 nanoparticle film. These films also showed biocidal properties upon UV-A irradiation. The elaboration of a one-pot method, combining the photo-induced synthesis of Ag nanoparticles and the LbL deposition of TiO2 nanoparticle layer, allowed the direct synthesis of Ag nanoparticles within the films and a high enhancement of the film photocatalytic properties. The construction methods were successfully transfered on textile surfaces. The films were photocatalytically active and biocidal under UV-A irradiation after several washing treatment cycles.
Download or read book Preparation and Characterization of Copper doped and Silver doped Titanium Dioxide Nano catalysts for Photocatalytic Applications written by Haya Abdel Raouf Ahmed and published by . This book was released on 2015 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this work was to improve the performance of TiO2 nanomaterials by increasing their optical activities by shifting the onset of the response from the UV to the visible-light region. Among the several ways to achieve this goal, doping TiO2 nanomaterials with other elements (e.g. metals) was selected to narrow the band gap and enhance the optical properties of TiO2 nanomaterials. In this work, we have prepared Cu-doped TiO2 and Ag-doped TiO2 nano-catalysts, characterized them and studied their properties, and the optical ones in particular. The Ag-doped TiO2 catalyst was prepared by the sol-gel method while the Cu-doped TiO2 catalyst was prepared by using two different techniques for comparison purposes: the sol-gel method and the inert gas condensation technique under ultra-high vacuum. The Ag-doped TiO2 nano-catalysts prepared by the sol-gel method were characterized by using Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Electron Probe Micro-Analyser (EPMA) for surface morphology and chemical composition, Brunauer-Emmett-Teller (BET) analysis for surface area and porosity measurements, X-ray diffraction (XRD) to determine their crystal structure and UV-visible absorption spectrometry (UV-Vis) to measure the optical properties. The same characterization methods have been applied on the Cudoped TiO2 photocatalysts prepared by the sol-gel method, in addition to some rheological measurements to determine their flow behaviour. Furthermore, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV-visible absorption spectrometry (UV-Vis) analyses have been conducted to characterize the Cu-doped TiO2 catalysts prepared by the inert gas condensation technique. vii The experimental work conducted here revealed promising results for improving the performance of the TiO2 nano material by doping it with Cu and Ag metals where the optical activity was enhanced and shifted to the visible region causing an appreciable increase in its effectiveness for photo catalytic applications.
Download or read book Synthesis of Titanium Dioxide Hetero structures for Photovoltaic Energy Conversion written by Jongbok Park and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The photovoltaic energy conversion system (PV cells or solar cells) has been researched over the last few decades, and new technologies have been proposed. At the same time, the synthesis of nano-scale materials has been investigated intensively from the 1990s. These new types of materials encourage the development of new PV technologies with extensive research. Dye-sensitized solar cells (DSSCs) can be a part of these efforts. Since first presented in 1991, DSSCs have become the center of attention due to their great advantages to the traditional silicon solar cells. However, it remains a challenge to develop better performing DSSCs since the efficiency of DSSCs is still much lower than that of high performance solar cells. To meet this challenge, the different types of TiO2 nanostructures in DSSCs have been studied. This thesis presents the synthesis of TiO2 hetero-structures. These structures can achieve two important factors in DSSCs. One is the electron pathway for high electron transport rate, and the other is the large surface area for the dye absorption. TiO2 hetero-structures were successfully synthesized by using a simple thermal annealing method. The synthesis method required neither a high reaction temperature nor complicated reaction processes and produced dense TiO2 nanowires and incorporating TiO2 nanoparticles with relatively short reaction time. The key parameters of growing 1-D TiO2 nanostructures were the Cu eutectic catalyst, the reaction temperatures, and the annealing time. The repetition time and the reaction temperatures were important factors for incorporating TiO2 nanoparticles. The structure and composition of as-grown samples were analyzed using an x-ray diffractometer, a scanning electron microscope, a field emission scanning electron microscope, a transmission electron microscope and an ultraviolet-visible spectroscopy. The results showed they were crystalline structures in rutile phase of TiO2. From this research, we can utilize hetero-structures as an electrode of DSSCs. We also expect that our simple and effective synthesis method can be used for growing other kinds of metal oxide nanostructures, especially for those melting temperature are high.
Download or read book Synthesis and Characterization of Undoped and Ag Doped TiO2 ZnO and ZnS Nanoparticles for the Photocatalytic Degradation of 2 chlorophenol Under UV Irradiation written by and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phenol, 2-chlorophenol (2-CP) is used in the manufacture of several chemical compounds including other chlorophenols, dyes, dentifrice and pesticides. The usage of these chemicals results in the discharge of 2-CP that is harmful to most biota in the environment. Therefore there is need to remove or degrade 2-CP from the environment, especially in water.
Download or read book Structural and Morphological Modification of TiO2 Doped Metal Ions and Investigation of Photo induced Charge Transfer Processes written by Jesus Vargas Hernandez and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis work is focused on the synthesis methods of titanium dioxide nanostructures and their physico-chemical studies in order to point out the correlations between the morphology, metal doping, structural features with the photocatalytic efficiency. The great interest on TiO2 nanomaterials deals with new sources of energy or in the environment preservation through the photocatalytic properties. However, the main limitations is due to the wide band gap (~3.2 eV) of the anatase polymorph. Thus, a major objective for improvement of the performance of TiO2 nanomaterials is to increase theirphotoactivity by shifting the onset of the electron-hole pairs creation from UV to the visible range. Moreover, it was found that using onedimensional (1-D) TiO2 (nanotubes) improved the charge collection by 1D nanostructures which consequently minimizes the recombination and prolongate the electron lifetimes. The first part of this work is focused on the synthesis of TiO2 nanopowders doped with metallic ions (Ag, Cu, Eu) prepared by Solgel. Even with different doping elements which apparently can adopt the same valence state (2+) such as (Cu2+, Ag2+,Eu2+), different behaviors were demonstrated for the effective incorporation of these ions in the host structure of TiO2. The discrepancy between ionic radii of the different used elements modulates the ratio of the substitutional doping. This is indeed achieved for Cu2+ but in less extent for Ag2+ while Europium ions form segregated phase as Eu2Ti2O7. The experiments on the degradation of methylene blue (MB)dyes have shown slight improvement with Ag-doped samples. The reason was tentatively attributed to the Ag clusters which were indeed demonstrated through their plasmon optical band. The second part of the work concerns thin films of TiO2 doped (Cu, Ag, and Eu) which were elaborated by spin coating and dip coating. The optimal parameters were obtained to achieve crystalline films but presenting mesoporous organisation which also depends on the doping process. Photocatalysis investigations were also realized and the efficiency of the films compared as function of the doping elements.The third part of the thesis is related to the morphological modification from nanoparticles to nanotubes by using the hydrothermal method with controlled pressure. An experimental design based on Taguchi Method was employed for the determination of the optimal parameters. TiO2 nanotubes increase the surface area in comparison with TiO2nanoparticles. TiO2 nanotubes were tested for the methylene blue degradation and show a higher photocatalytic efficiency than TiO2 nanopowders and TIO2 doped with Ag.
