Synthesis Of TiO2 Research Articles

Bottom-Up Synthesis of Mesoporous TiO2 Films for the Development of Optical Sensing Layers

Many optical sensors exploit the interesting properties of porous materials, as they ensure a stronger interaction between the light and the analyte directly within the optical structure. Most porous optical sensors are mainly based on porous silicon and anodized aluminum oxide, showing high sensitivities. However, the top-down strategies usually employed to produce those materials might offer a limited control over the properties of the porous layer, which could affect the homogeneity, reducing the sensor reproducibility. In this work, we present the bottom-up synthesis of mesoporous TiO2 Fabry-Pérot optical sensors displaying high sensitivity, high homogeneity, and low production cost, making this platform a very promising candidate for the development of high-performance optical sensors.

Phosphonium ionic liquid-promoted Ce-doped nitrogen-rich TiO2 for degradation gaseous pollutant under visible light irradiation

Altering physicochemical properties of TiO2 based on modifying the cation and anion structure of ionic liquids (ILs) is of great interests for environment. Up to date, the research involving IL-assisted synthesis of TiO2 was focused on imidazolium IL, and much less attention was devoted to IL with other structures. Hence, strategy for preparation of TiO2 in phosphonium IL is presented to control the growth of TiO2 nanocrystals. The as-prepared noble cerium-doped nitrogen-rich phosphonium IL-TiO2 photocatalyst with assisted by tributyl(propyl)phosphonium tetrafluoroborate exhibits a higher specific surface area and smaller crystallite size, which is conducive to the production of more and faster active substance, such as hydroxyl oxygen. When evaluated for photocatalysis of gaseous toluene under visible light irradiation, the sample manifests high degradation rate and efficiency, as well as excellent recycling performance due to the existence of superoxide radical produced by the Ce3+/Ce4+ redox reaction. The introduction of phosphonium IL and Ce greatly enhanced charge separation efficiency and promoted production of active substances. Nitrogen also existed in the form of interstitial nitrogen and substituted nitrogen improves its response to visible light. This work shows promising application of phosphonium IL for highly enhanced TiO2 photocatalytic performance.

Synthesis, Characterisation, Photocatalytic Activity, and Aquatic Toxicity Evaluation of TiO2 Nanoparticles.

Imidacloprid (IMD) is a toxic pesticide, and is one of the eight most widely used pesticides globally. Heterogeneous photocatalysis has often been investigated in recent years and can be successfully applied to remove imidacloprid from water. However, less investigated is the toxic effect of both the photocatalyst and the pesticide on aquatic life. Titanium dioxide (TiO2) remains the most effective photocatalyst, provided it is not toxic to the aquatic environment. This study investigated the TiO2 synthesis, characterisation, and photocatalytic activity on imidacloprid degradation and the toxicity of TiO2 nanoparticles and imidacloprid on the green algae Chlorella vulgaris. In the photodegradation process of IMD (initial concentration of 20 mg/L), electrons play an essential role; the degradation efficiency of IMD after 6 h increased from 69 to 90% under UV irradiation when holes (h+) scavengers were added, which allowed the electrons to react with the pollutant, resulting in lowering the recombination rate of electron-hole charge carriers. Growth inhibition of Chlorella vulgaris and effective concentration (EC50) were determined to study the toxic effect of TiO2 nanoparticles and imidacloprid. The EC50 increased from 289.338 mg/L in the first 24 h to 1126.75 mg/L after 96 h Chlorella vulgaris algal age, when the toxicant was TiO2. When IMD was the aquatic toxicant, a decrease in EC50 was observed from 22.8 mg/L (24 h) to 0.00777 mg/L (120 h), suggesting a long-term high toxicity level when pesticides in low concentrations are present in an aquatic environment.

Nanoencapsulation of isotropic and anisotropic particles through a green chemistry aerosol method: a scalable approach for ad-hoc surface tuning

The interest in core–shell materials with chemically tunable mesoporous surfaces has significantly grown in recent years. The main limitation to obtain these systems through sequential precipitation is the tuning of the core and shell sol-gel chemistry, which usually implies low concentrations and leads to high-quality colloids although in small quantities after a lengthy and costly process. Aerosol approaches can lead to faster production and easier separation of functional materials with well-defined architectures. We present a “green chemistry” general method to coat sub-micron colloidal particles with a variety of mesoporous metal oxide nanofilms via an aerosol synthesis technique. Different types of particulate supports with isotropic and anisotropic shapes were dispersed into the precursor solutions in order to synthesize a mesoporous shell keeping the shape of the support. We chose the synthesis of TiO2 and TiSiO4 nanofilms on conventional Stöber SiO2 spherical particles, and on anisotropic micronized mica particles as a case study. We used the commercial surfactant Pluronic® F127 as a porogen. The structure and composition of the obtained nanofilms were characterized by electron microscopy, X-ray diffraction, focused ion beam coupled to SEM, and nitrogen adsorption/desorption isotherms. The TiO2 shells obtained (with an anatase-like structure) have pore diameters between 3.9–4.8 nm depending on the support with film thicknesses of ~100 nm, while amorphous TiSiO4 shells have larger diameters (9.5–16 nm) with film thicknesses of between 50 and 200 nm depending on the support used. The method presented shows high reproducibility and, unlike batch methods, allows the continuous production and straightforward recovery of the materials.

Interaction of levofloxacin with reverse micelle sol-gel synthesized TiO2 nanoparticles: Revealing ligand-to-metal charge transfer (LMCT) mechanism enhances photodegradation of antibiotics under visible light

Synthesis of TiO2 through reverse micelle sol–gel (RMS) route showed 18 nm mean diameter with homogeneous particle size distribution (PDI = 0.11). TiO2 nanomaterial with a bandgap of 3.15 eV exhibited degradation efficiency of 83% towards levofloxacin (LFX) aqueous pollutant of 50 mg/L under 6H of the visible LED light. Visible light photoactivity ascribed to ligand to metal charge transfer (LMCT) process between the targeted antibiotic pollutant and titania photocatalyst. At neutral pH, photocatalytic degradation performance of TiO2 was observed higher due to adsorption of LFX through N of piperazinyl ring causing LMCT. The basic pH encouraged adsorption of LFX through the carboxylate group, which showed comparatively lesser activity. In acidic pH conditions, the lowest photoactivity resulted from the synergetic effect of lower adsorption and participation of the ketone-carboxyl adsorption site of LFX with TiO2.

The synthesis of zirconium and tetraethylenepentamine bi-functionalized TiO2 for efficient CO2 adsorption

In the present work, zirconium-doped metal oxide of TiO2(ZrN) was synthesized and functionalized with different amount of tetraethylenepentamine (TEPA). The physical properties of the materials were tested using temperature-programmed desorption of NH3, X-ray diffractometer, X-ray photoelectron spectrometer, scanning electron microscope, transmission electron microscope, energy dispersion spectrum, Inductively coupled plasma atomic emission spectroscopy, Infrared spectrometer, N2 adsorption-desorption analyzer, energy dispersion spectrum and thermogravimetric analyzer. Zr species has a positive effect on the enhancement of the thermal stability and amine utilization. After the introduction of Zr, the decomposition temperature of TEPA is improved to 180℃. Over TEPA decorated adsorbents, physical adsorption and chemical adsorption occurs simultaneously. When the adsorption time is 75℃, CO2 flow rate is 20 mL/min, the adsorbent of TEPA(40)/TiO2(Zr0.1) exhibit a remarkable amine utilization of 83.5%.

Synthesis and characterization of TiO2: Al thin films for bacteria resistance in the implanted dental

Synthesis and characterization of TiO2: Al thin films for bacteria resistance in the implanted dental

Ultrathin SnS2 Nanosheet Decorated B-TiO2 / TiO2 Core Shell Nanorods for Photoelectrochemical Water Splitting

Morphology tailoring and heterostructure designing has emerged as one of the most significant frontrunners in research on photoelectrochemical water splitting. In this work we demonstrate the synthesis of core shell Black TiO2 @ TiO2 nanorods by a one step electrochemical treatment using NaBH4 to partially reduce surface Ti4+ ions to Ti3+ by chronoamperometry in order to generate a core shell structure. The effect of anodic potential for the electrochemical reduction process was studied. The fabricated electrodes were further decorated with SnS2 nanosheets by a facile solvothermal method to generate a ternary SnS2 / B-TiO2 @ TiO2 heterojunction. The photoelectrochemical performance of the fabricated photoanodes were analyzed using A.M 1.5 G solar simulator with a anodic potential sweep from -0.5 V to 2 V. A maximum ABPE % of 1.12 % was observed at 0.61 V using Na2S / Na2SO3 as an electrolyte. DFT calculations were carried out to understand the underlying electronic structure of the heterostructure and charge transfer pathways. Morphological analysis was carried out using characterization techniques like XRD and SEM. Optical analysis was carried out using UV-Vis spectra and PL measurements. Charge transfer kinetics were analyzed using EIS and Mott-Schottky plots. This work hopes to inspire further research in the designing of ternary heterostructures by electrochemical surface treatment of semiconductor nanostructures.

Photoelectrochemical IL-6 Immunoassay Manufactured on Multifunctional Catecholate-Modified TiO2 Scaffolds.

There is an increasing interest in using photoelectrochemistry for enhancing the signal-to-noise ratio and sensitivity of electrochemical biosensors. Nevertheless, it remains challenging to create photoelectrochemical biosensors founded on stable material systems that are also easily biofunctionalized for sensing applications. Herein, a photoelectrochemical immunosensor is reported, in which the concentration of the target protein directly correlates to a change in the measured photocurrent. The material system for the photoelectrode signal transducer involves using catecholate ligands to modify the properties of TiO2 nanostructures in a three-pronged approach of morphology tuning, photoabsorption enhancement, and facilitating bioconjugation. The catecholate-modified TiO2 photoelectrode is combined with a signal-off direct immunoassay to detect interleukin-6 (IL-6), a key biomarker for diagnosing and monitoring various diseases. Catecholate ligands are added during hydrothermal synthesis of TiO2 to enable the growth of three-dimensional nanostructures to form highly porous photoelectrodes that provide a three-dimensional scaffold for immobilizing capture antibodies. Surface modification by catecholate ligands greatly enhances photocurrent generation of the TiO2 photoelectrodes by improving photoabsorption in the visible range. Additionally, catecholate molecules facilitate bioconjugation and probe immobilization by forming a Schiff-base between their -COH group and the -NH2 group of the capture antibodies. The highest photocurrent achieved herein is 8.89 μA cm-2, which represents an enhancement by a factor of 87 from unmodified TiO2. The fabricated immunosensor shows a limit-of-detection of 3.6 pg mL-1 and a log-linear dynamic range of 2-2000 pg mL-1 for IL-6 in human blood plasma.

Synthesis of Different Sizes TiO2 and Photovoltaic Performance in Dye-Sensitized Solar Cells

For more than 2 decades, extensive research has been done in the field of Dye-Sensitized Solar Cells (DSSCs) due to their low cost, easy preparation methodology, less toxicity, and ease of production. In this work, the performance of DSSCs containing different particle sizes is studied. N2-doped TiO2was prepared by the sol-gel method, controlling the particle size through the addition of different H2O/Ti mole ratios R = 0, 20, 30, and 40. The dried samples at 100°C were characterized by X-ray diffraction, Optical Properties, High-Resolution Transmission Electron Microscope, Scanning Electron Microscope, Fourier-Transform Infrared Spectroscopy, N2-Adsorption-Desorption Isotherm, Raman Spectroscopy, and Dynamic Light Scattering (DLS). DLS results show that the size of TiO2decreases as the H2O/TiO2content increases from 0 to 40. It is found that TiO2nanoparticles with smaller particle size distribution has the lowest conversion efficiency of 0.95% with H2O/Ti ratio = 40, and the photoelectrode with higher size has a conversion efficiency of 1.59% for the water-free sample. This could be explained as the larger particles have better dye adsorption, indicating that it has an effective surface area for greater photon absorption and electron-hole generation. The results also indicate that trimodal distribution with larger size also absorbs different wavelengths due to the broad distribution of the particle size.

One-Pot Synthesis of Nitrogen-Doped TiO2 with Supported Copper Nanocrystalline for Photocatalytic Environment Purification under Household White LED Lamp.

Developing efficient and cheap photocatalysts that are sensitive to indoor light is promising for the practical application of photocatalysis technology. Here, N-doped TiO2 photocatalyst with loaded Cu crystalline cocatalyst is synthesized by a simple one-pot method. The structure is confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy analysis, which exhibit that Cu metal nanocrystalline is uniformly deposited on the surface of N-doped TiO2 material. UV-Vis absorption spectra illustrate that the modified samples possess favorable visible light absorption properties and suppressed-electron hole separation. The as-fabricated Cu-loaded N-TiO2 materials show high activity in photocatalytic decomposing isopropanol and inactivating E. coli under the irradiation of a household white LED lamp. The developed synthetic strategy and photocatalytic materials reported here are promising for indoor environment purification.

Caffeine photocatalytic degradation using composites of NiO/TiO2–F and CuO/TiO2–F under UV irradiation

The interest in the removal of emerging contaminants has increased in the last decade. Photocatalytic degradation using p-n heterojunctions could effectively provide the degradation of these type of substances that are persistent in the environment. In this work, the synthesis, characterization, and photocatalytic evaluation of TiO2–F as well as CuO/TiO2–F and NiO/TiO2–F composite materials were studied in the photo-assisted degradation of caffeine using UV radiation. The fluorination of titanium dioxide induced changes in some physicochemical properties of the materials, which contributed to a decrease in surface area and bandgap energy as well as an increase in crystallite size as compared to pristine TiO2. ≡Ti–F species were evidenced to be formed, which could favor charge separation processes. A highest segregation of CuO species in comparison with NiO on the surface of TiO2–F could be formed, which could increase defect sites and decrease the band gap. The formation of a heterojunction between the semiconductors was evidenced, responsible for the observed improvements in photocatalytic properties of the composite materials. The photocatalytic tests evidenced an important degradation of caffeine; however, mineralization was incomplete. The stability of the composite materials and their potential use in the photocatalytic treatment of caffeine was evaluated by reuse tests.

Microplasma-assisted synthesis of TiO2–Au hybrid nanoparticles and their photocatalytic mechanism for degradation of methylene blue dye under ultraviolet and visible light irradiation

Plasmonic photocatalysts consisting of TiO2 and Au nanoparticles (NPs) have recently been intensively studied to overcome the limited photocatalytic activity of pristine TiO2 NPs. Here, we synthesized TiO2–Au hybrid NPs using atmospheric microplasma–liquid interaction and demonstrated their enhanced photocatalytic activity, under both ultraviolet (UV) and visible light irradiation, for the degradation of the organic dyes methylene blue (MB) in water. Through mechanism studies using a hole scavenger and external source of hydroxyl radicals, it was also revealed that the contribution of hole oxidation and electron reduction pathways for degradation of MB via hydroxyl radicals by the TiO2–Au hybrid NPs differed depending on the wavelength of irradiating light. This is because the MB dye is likely remotely oxidized under UV irradiation, but not under visible light. This systematic study on the role of hole and electron pathways for photocatalytic dye degradation by TiO2–Au hybrid NPs at different light and pH conditions is helpful for understanding and developing plasmonic photocatalysts.

Synthesis of TiO 2 Using Calotropis gigantea for Visible Light Excitation and Degradation of Congo Red Dye

Green synthesized TiO2 (CG-TiO2) was prepared from Titanium isopropoxide (TTIP) precursor using aqueous leaf extract of Calotropis gigantea (CG). The CG-TiO2 was prepared with different mixing ratios of CG and TTIP varying from 1:3 to 1:5 and at different synthesis conditions, that is, mixing time, temperature, and calcination temperature. Morphological analysis indicated spherical nanoparticle clusters of CG-TiO2 with particles of an average size of 42 nm. The study indicated visible light excitation of CG-TiO2 and effective removal of Congo red from aqueous solution under visible light irradiation. A maximum Congo red removal efficiency of 97% was obtained within 2 h under the following conditions: Sample B (30 g leaves in 100 mL distilled water boiled for 2 h at 90°C); TTIP:CG – 1:3; mixing time and temperature – 2 h and 27°C, respectively; calcination temperature – 300°C.

Synthesis of TiO2 nanotubes/nickel-gallium layered double hydroxide heterostructure for highly-efficient photocathodic anticorrosion of 304 stainless steel

The corrosion of 304 stainless steel (304SS) is a major global issue in the context of ships and marine engineering constructions. The photocathode anticorrosion system, composed of semiconductor material in the form of photoanode and 304SS in the form of cathode, is an effective method to solve 304SS corrosion of large components. Owing to the rapidly photoinduced charge-transfer at the semiconductor interface that supplies photogenerated electrons to the electrically connected 304SS and shifts the coupled potential to much more negative values, constructing a photoanode heterostructure material promotes charge separation and thus improves the photocathodic anticorrosion of 304SS. Herein, we fabricated TiO2 nanotubes/nickel‑gallium layered double hydroxide (TiO2/NiGa-LDH) heterostructure material by the electrochemical anodization and hydrothermal method for highly-efficient photocathodic anticorrosion of 304SS. Owing to the modulated band structure and enhanced photogenerated carriers separation and transfer, TiO2/NiGa-LDH heterostructure material gave rise to largely reduced open circuit potential (OCP, −690 mV), which facilitated the transfer of electrons from the TiO2/NiGa-LDH heterostructure material to the 304SS to improve the photocathodic anticorrosion of 304SS, along with good stability after the OCP test for 72 h. This work provides a strategy for exploring LDH-based photoanodes materials toward highly-efficient photocathodic anticorrosion of 304SS.

Synthesis of TiO2 from TiCl4 Using Morinda Citrifolia Root Extract as a Molecular Template and its Photocatalytic Activity to Methylene Blue Degradation

TiCl4 successfully as precursors for synthesised TiO2 in nanometer-sized through the sol-gel method on the variation of the concentration of root extract of M. Citrifolia and have shown photocatalyst activity to degrade methylene blue with UV radiation in 365 nm. The characteristics of TiO2 synthesized such as crystalline, size and morphology using SEM. SEM analysis showed that the morphology of TiO2 synthesized showed the spherical shape in the nanometer-sized. Examination of the energy bandgap using UV-Vis DRS showed a decrease bandgap for TiO2 synthesized (TiO2 Merck = 3.2 eV; TiO2 10x = 3:16 eV; TiO2 50x = 3.1 eV; TiO2 100x = 3.08 eV). The best degradation photocatalytic activity is demonstrated by TiO2 100x until 84.07%. The reaction rate of TiO2 photocatalytic for the degradation of methylene blue follow a pseudo-second-order reaction model.

Liquid impregnation and sol-gel routes synthesis of tailored titania NPs for the effective water remediation processes

This work is designed for the synthesis of TiO2 and Fe doped TiO2 nanoparticles (NPs) using sol-gel (SG) and liquid impregnation (LI) methods. The comparison of physicochemical characters, the photocatalytic potential of pure and doped NPs, and cost analysis of the techniques were evaluated. The prepared NPs were characterized through XRD, BET/BJH, SEM, UV-Vis DRS, and pH of the point of zero charges (pH PZC ) analyses. The results have shown the dominant anatase phase of highly pure crystalline NPs. The SG prepared pure and Fe doped TiO2 NPs revealed with high surface area (242 and 245 m2/g, respectively) as compared to the materials prepared via LI technique (57.5 and 82 m2/g, respectively). The photocatalytic potential of the prepared NPs was tested for cationic dye (Methylene Blue) and anionic dye (Methyl Orange) under ordinary visible light (Compact Fluorescent Light). The green route synthesis i.e. LI doped NPs, revealed high photo-degradation efficiencies for Methylene Blue and Methyl Orange (87 and 84%) compared to SG prepared doped NPs (76 and 70%), respectively.

Environmental photochemistry with Sn/F simultaneously doped TiO2 nanoparticles: UV and visible light induced degradation of thiazine dye

Environmental route such as degradation of toxic dyes can be improved through photochemical activity such as light driven photocatalytic degradation. Herein, fluorine and tin simultaneously doped TiO2 nanoparticles were synthesized and characterized. The formation of anatase phase in synthesized samples and the reduction in the crystallite size of doped TiO2 was confirmed from XRD results. The existence of O–Ti–O stretching vibration in pure and co-doped TiO2 confirmed from FTIR results. Optical studies reveal that the band gap of co-doped TiO2 is increased and hence it was concluded that the particle size of co-doped TiO2 is reduced compared with as-synthesized TiO2. The morphologies of TiO2 changed significantly with doping of fluorine and tin. It reveals majority of the particles are hexagons, pentagons and ellipse shaped and some of them are spheres with a mean particle size of 31.17 nm. PL studies showed the reduction in intensity for Sn–F/TiO2 accredited to the lesser recombination rate of electron-hole pair under UV light irradiation. Thus tin and fluorine doped TiO2 could be considered as a good candidate for photocatalytic activity. The photocatalytic activity of TiO2 and Sn–F/TiO2 nanoparticles was analyzed separately through the degradation of methylene blue (MB) under visible and UV light irradiation. The use of Sn and F ions in the synthesis of TiO2 are revealed not only create small sized nanoparticles but these water soluble nanoparticles have very good antibacterial and antifungal action by inhibiting the growth of bacteria and fungus.

W-Doped TiO2 Nanorods for Multimode Tumor Eradication in Osteosarcoma Models under Single Ultrasound Irradiation.

Sonosensitizers play crucial roles in the controlled production of reactive oxygen species (ROS) under ultrasound (US) irradiation with high tissue-penetration depth for noninvasive solid tumor therapy. It is desirable to fabricate structurally simple yet multifunctional sonosensitizers from ultrafine nanoparticles for ROS-based multimode therapy to overcome monomode limitations such as low ROS production yields and endogenous reductive glutathione (GSH) to ROS-based treatment resistance. We report the facile high-temperature solution synthesis of ultrafine W-doped TiO2 (W-TiO2) nanorods for exploration of their sonodynamic, chemodynamic, and GSH-depleting activities in sonodynamic-chemodynamic combination tumor therapy. We found that W5+ and W6+ ions doped in W-TiO2 nanorods play multiple roles in enhancing their ROS production. First, W doping narrows the band gap from 3.2 to 2.3 eV and introduces oxygen and Ti vacancies for enhancing their sonodynamic performance. Second, W5+ doping endows W-TiO2 nanorods with Fenton-like reaction activity to produce •OH from endogenous H2O2 in the tumor. Third, W6+ ions reduce endogenous GSH to glutathione disulfide (GSSG) and, in turn, form W5+ ions that further enhance their chemodynamic activity, which greatly modifies thae oxidation-reduction tumor microenvironment in the tumor. In vivo experiments display the excellent ability of W-TiO2 nanorods for enhanced tumor eradication in human osteosarcoma models under single US irradiation. Importantly, the ultrafine nanorod morphology facilitates rapid excretion from the body, displaying no significant systemic toxicity. Our work suggests that multivalent metal doping in ultrafine nanomaterials is an effective and simple strategy for the introduction of new functions for ROS-based multimode therapy.

Photocatalytic decolorization of an azo dye employing TiO2 anatase/brookite compounds obtained by hydrothermal methods

Titanium dioxide is a widely studied material with well-known applications for anatase and rutile phases. Moreover, brookite, another polymorph, which is more difficult to obtain, has caught scientific community interest, especially for photocatalysis applications. Among many methodologies for TiO2 synthesis, the hydrothermal method stands out, with the possibility of controlling different parameters that lead to a specific phase composition, allowing selective polymorphic obtainment. This method was used to synthesize TiO2 with different anatase/brookite ratios, by the use of different synthesis conditions as pH of the suspension, sodium salt concentration, and temperature, resulting in anatase-brookite photocatalyst with brookite composition ranging from 0 to 35%. The materials were characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, particle size measurement, and scanning electron microscopy. Photocatalysts with the highest brookite amount showed the best photocatalytic results for Remazol golden yellow (RNL) dye decolorization. Moreover, the short-range disorder also played an important role in photocatalytic behavior.