Synthesis Of TiO2 Nanoparticles Research Articles

Sol-gel preparation and characterization of Er3+ doped TiO2 luminescent nanoparticles

The present paper reports on down-and up-conversion luminescence behaviour of sol-gel derived erbium doped titanium dioxide with anatase structure. Through combined structural, optical and electron microscope analysis, effective and influence of Er3+ doping into TiO2 lattice has been demonstrated using X-Ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and optical reflectance spectra. XRD results showed only anatase diffraction peaks of TiO2, indicating the formation of a pure anatase phase even after Er3+ incorporation into TiO2 lattice. Selected Area Electron Diffraction (SAED) confirmed that the synthesized TiO2 nanoparticles are polycrystalline in nature which correlated well with XRD findings. Upon excitation at 320 nm, two down-conversion contributions at 378 nm and 435 nm attributed to indirect band gap and defect-related emissions, respectively were observed from both pure and Er3+ doped TiO2 nanoparticles. On the other hand, strong green up-conversion emission centred at 544 nm ascribed to 4S3/2 → 4I15/2 transition of Er3+ was observed under 980 nm laser excitation for all Er3+ doped TiO2 samples. This result analysis brings insight on understanding of structural, optical and luminescence properties of Er3+ doped TiO2 nanoparticles for use in solar cells and bio imaging devices.

TiO2/carbon dots decorated reduced graphene oxide composites from waste car bumper and TiO2 nanoparticles for photocatalytic applications

Upcycling waste car bumper to value added carbon based nanomaterials has been achieved through facile catalytic pyrolysis. As synthesized TiO2 nanoparticles has been used for the first time as catalyst during pyrolysis process of the plastic waste. The quality and the performance of the produced carbon nanomaterials have been evaluated through different characterization techniques. The results show that, while rGO were produced from the thermal pyrolysis of waste car bumper in absence of TiO2 catalyst, rGO decorated with carbon dots have been produced in presence of TiO2 catalyst. Interestingly, simultaneous TiO2 rutile to anatase phase transformation and carbon nanomaterials formation has been occurred upon the catalytic transformation of the waste car bumper, however, an expected anatase to rutile transformation has been observed upon thermal treatment of TiO2 in the absence of the bumper. The photocatalytic performance of the created TiO2/CDs/rGO has been tested for the photocatalytic degradation of methylene blue. This paper provides a first attempt as an innovative approach to the upcycling waste into novel and high performance carbon nanomaterials for the application in photocatalysis. This innovative approach can be utilized to create various carbon nanocomposites utilizing metal oxides as catalyst and different plastic waste system as a carbon resource.

Synthesis of TiO2 nanoparticles via a simple precipitation method and photocatalytic performance

Titanium dioxide nanoparticles were prepared by a simple precipitation method using titanium (IV) isopropoxide as a starting material. The precursor powder was calcined in air at temperatures ranging from 400 to 700 °C. XRD analysis results revealed that the crystallite size and crystallinity of the samples increased with increasing calcination temperature. The morphology and particle size of TiO2 particles were investigated with TEM images and the diameter of the particles was then calculated using the images. It was evident that the calcination temperature had a significant influence on the average particle size since the size increased from 11.3 to 27.4 nm when the temperature was raised from 400 to 700 °C. By extrapolating the graph of (αhv)n versus photon energy (hv) to the horizontal axis, the energy band gap (Eg) of the calcined TiO2 nanoparticles was in the range of 2.98–3.30 eV. Under UVA irradiation, photodegradation activity of methyl orange had the fastest kinetics as measured by areaction rate constant, k, using the pure anatase TiO2 nanoparticle calcined at 400 °C.

Oxidative denitrogenation with TiO2@porous carbon catalyst for purification of fuel: Chemical aspects

In order to investigate the possible denitrogenation of fuels, oxidation of organonitrogen compounds (ONCs) was carried out by using H2O2 green oxidant over a TiO2-containing carbon catalyst, prepared by the pyrolysis of an MOF-composite [ZIF-8(30)@H2N-MIL-125] (named as MDC-C). Neutral ONCs, including indole (IND) and its derivatives, especially those with high electron density on the nitrogen of the ONCs, different from basic ONCs, could be effectively oxidized, especially in the presence of a suitable extracting solvent CH3COOH. MDC-C showed a high turnover frequency in the oxidation of IND as compared with various commercial or synthesized TiO2 nanoparticles. The used catalyst could be recycled by simple solvent washing up to the fourth run without severe deactivation. Therefore, it could be confirmed that MDC-C is very effective in oxidative denitrogenation to remove ONCs, especially neutral ones, from fuels in the presence of H2O2 and a suitable extractant. Importantly, oxidation of IND derivatives was performed firstly under similar conditions in order to understand the mechanism of the reaction. The results showed that high electron density (that calculated in this study) on the nitrogen of the IND and its derivatives is very important, suggesting that the electrophilic addition of oxygen atoms onto the substrates (via N on the INDs) might play a crucial role in the oxidation, even though further study is essential to support this assumption.

Synthesis, characterization of TiO2 nano particles for enhancement of electron transport application in DSSC with Cu-BPCA Dye

Dye-sensitized solar cells [DSSCs] have attracted extensive attention due to their potential low cost and high energy efficiency, rendering them one of the most promising system for solar-to-energy conversion. The DSSC efficiency was enhanced by intermixing with the use of TiO2 nanoparticles which provides high surface area for accommodating the light-absorbing sensitizer and also the stable conductor for photo generated electrons. In hydrothermal method, the TiO2 nanoparticles synthesis depends on temperature. TiO2 nano particles diameter depends on different autoclaving temperature. TiO2 nanoparticles have been coated on ITO glasses by screen printing method. In this work, we have synthesized TiO2 nano particles which can provide a fast way for electron transport and reduced trapping of photo injected electrons during the path of back contact. The DSSCs were fabricated using the ruthenium dye and electrolyte (I3/I3-). The crystalline structure of TiO2 has been characterized by DLS, X-ray diffraction, SEM and TEM. The absorption spectra measured by using UV-Vis spectrometer. The IR spectrum has been recorded to know the peaks of Ti-O-Ti in powder sample. It has been found that the efficiency of DSSC was highly affected by the properties of nano particles.

Low Temperature Synthesis of Anatase TiO<sub>2</sub> Nanoparticles and its Application in Nanocrystalline Thin Films

The nano-sized TiO2is an important material based on its application for solar cells. The low-cost synthesis of nano-sized TiO2is of high demand for commercial purposes. Synthesis of TiO2nanoparticles was achieved via the low-temperature Sol-gel method. Surface morphology was confirmed from SEM analysis, which showed that particle size is in the range of nanometer with no aggregation, The XRD results confirm the formation of anatase phase with high crystallinity. Furthermore, as prepared nano-sized TiO2particles were developed as sol-gel ink which was later deposited by spin coating on glass substrate with controlled spinning speed thereafter structural and optical properties were characterized by UV-vis spectroscopy, electrochemical impedance spectroscopy and DSC-TGA. The low-cost synthesis of TiO2nanoparticles with highly conductive thin films can be used as a potential material for future dye-sensitized solar cells

Highly Sensitive, Temperature-Independent Oxygen Gas Sensor Based on Anatase TiO2 Nanoparticle Grafted, 2D Mixed Valent VO x Nanoflakelets.

Herein, we report a facile approach for the synthesis of TiO2 nanoparticles tethered on 2D mixed valent vanadium oxide (VO x/TiO2) nanoflakelets using a thermal decomposition assisted hydrothermal method and investigation of its temperature-independent performance enhancement in oxygen-sensing properties. The material was structurally characterized using XRD, TEM, Raman, DSC, and XPS analysis. The presence of mixed valent states, such as V2O5 and VO2 in VO x, and the metastable properties of VO2 have been found to play crucial roles in the temperature-independent electrical conductivity of VO x/TiO2 nanoflakelets. Though pristine VO x exhibited characteristic semiconductor-to-metal transition of monoclinic VO2, pure VO x nanoflakelets exhibited poor sensitivity toward sensing oxygen. VO x/TiO2 nanoflakelets showed a very low temperature coefficient of resistance above 150 °C with improved sensitivity (35 times higher than VO x for 100 ppm) toward oxygen gas. VO x/TiO2 nanoflakelets exhibited much higher response, faster adsorption and desorption toward oxygen as compared to pristine VO x beyond 100 °C, which endowed the sensor with excellent temperature-independent sensor properties within 150-500 °C. The faster adsorption and desorption after 100 °C led to shorter response time (3-5 s) and recovery time (7-9 s). The results suggest that 2D VO x/TiO2 can be a promising candidate for temperature-independent oxygen sensor applications.

(Invited) Self-Synthesized Titanium Di-Oxide (Tio2) Nanoparticles Based Sensor for Brain Signals Extraction

Titanium dioxide (TiO2) nanoparticles has been synthesized by using hydrothermal method. The effect of hydrothermal temperature and structure of the TiO2 nanoparticles are mentioned here. This paper describes the optical and structural properties of the self synthesized TiO2 nanoparticles using various characterization tools like UV-Visible spectrophotometer, X-ray diffraction, FESEM with EDAX etc, this work mainly concentrates on the MOS structure. MOS structure involves the silicon substrate as semiconductor, silicon dioxide as oxide layer, self synthesized TiO2 nanoparticles are the active layer and silver has used for contact. The electrical study for the MOS structure was carried out. Capacitance versus voltage (CV) and current versus voltage (IV) are the important characteristics has performs to conclude the MOS structure is working as sensor. Figure 1

The effect of titanium dioxide synthesis technique and its photocatalytic degradation of organic dye pollutants

Nanostructured mesoporous titanium dioxide (TiO2) particles with high specific surface area and average crystallite domain sizes within 2 nm and 30 nm have been prepared via the sol-gel and hydrothermal procedures. The characteristics of produced nanoparticles have been tested using X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), and Raman Spectroscopy as a function of temperature for their microstructural, porosity, morphological, structural and absorption properties. The as-synthesized TiO2 nanostructures were attempted as catalysts in Rhodamine B and Sudan III dyes' photocatalytic decomposition in a batch reactor with the assistance of Ultra Violet (UV) light. The results show that for catalysts calcined at 300 °C, ∼100 % decomposition of Sudan III dye was observed when Hydrothermal based catalyst was used whiles ∼94 % decomposition of Rhodamine B dye was observed using the sol-gel based catalysts. These synthesized TiO2 nanoparticles have promising potential applications in the light aided decomposition of a wide range of dye pollutants.

Investigation of the enhancement and optimization of the photocatalytic activity of modified TiO2 nanoparticles with SnO2 nanoparticles using statistical method

In this study, the pure TiO2 nanoparticles and two kinds of hybrids including decorated TiO2 nanoparticles with SnO2 nanoparticles (A-S (1-1) and A-S (1-2)) are synthesized by hydrolysis method in order to evaluate the photocatalytic activity. The synthesized photocatalysts are characterized using FTIR. The photocatalytic performance is recorded by variation of the photodecomposition of methyl orange as an organic pollutant with respect to the pH of solution (pH = 3, pH = 7 and pH = 11), UV irradiation time (ranging from 5 min to 20 min) and weight fraction of photocatalysts (0.1%wt, 0.2%wt and 0.3%wt). According to the obtained results based on Duncan’s multiple range test at α = 0.05, it can be confirmed that the variations of the removal efficiency with main factors are significant. Meanwhile, compared with TiO2 nanoparticles, the photocatalytic activity of A-S (1-1) and A-S (1-2) enhances and it depends on the amount of decorated SnO2 nanoparticles on the outer surface of TiO2 nanoparticles. The kinetic investigation of the photocatalytic reactions reveals that the photocatalytic reaction rate constant (kp) enhances with introducing the SnO2 nanoparticles to the TiO2 nanoparticles. Furthermore, based on the optimization results it is clear that the maximized values of removal efficiency using synthesized TiO2 nanoparticles, A-S (1-1) and A-S (1-2) are 97.46%, 98.57% and 99.17%, respectively.

Continuous ultrasonic stimulation based direct green synthesis of pure anatase-TiO2 nanoparticles with better separability and reusability for photocatalytic water decontamination

Titanium dioxide nanoparticles have shown a tremendous potential in various fields such as photocatalysis, solar-photovoltaics, electrodes, sensors, implants and pigments. Due to these versatile applications, their synthesis routes have gained a vast attraction and demand for being frugal and eco-friendly with better control over the anatase and rutile phase ratio. Comprehensively, the sol-gel method is a widely used technique for the synthesis of TiO2 nanoparticles that requires several additional chemical entities such as organic solvents, acids and capping agents. It makes this process quite uneconomical and hazardous in nature. In the present study, non-hazardous microwave and/or ultrasound based one-pot synthesis approaches have been studied for the production of phase controlled TiO2 nanoparticles and compared with the sol-gel synthesized and commercially available TiO2 nanoparticles. These comparisons have been validated through several material characterization techniques. The obtained results have shown that the ultrasound based synthesis followed by suitable thermal processing alone has tremendous potential to produce phase controlled TiO2 nanoparticles (preferably anatase phase), mostly in the form of nano-micro aggregates. In addition, the photocatalytic activity of ultrasonically synthesized TiO2 nanoparticles has also been examined and compared with that of the commercially available TiO2 nanoparticles. It is interesting to observe that, ultrasonically synthesized TiO2 nanoparticles have not only shown improvised photocatalytic degradation activity, but also shown a significant improvement on their separability and recyclability for water treatment applications, in comparison to that of the commercially available TiO2 nanoparticles (TiO2-P25).

Dielectric properties and bioactivity of PVA/PEG/TiO2 fibers for capacitive based body sensor

TiO2 nanoparticles are known as a material which widely used in optoelectronic, industrial, and health sectors application. This material has a controllable dielectric constant making it possible to be utilized as a capacitive based body sensor. Many efforts had been studied by means of synthesizing TiO2 nanoparticles in the form of conventional film depositions. It is also obtained that rare information of comprehensive study related to dielectric properties of the materials. In this report, we propose to synthesize PVA/PEG/TiO2 fibers using electrospinning method at various TiO2 concentration. Dielectric properties and bioactivity of samples are a focus of study. Electro spinning process has been performed with a voltage of 20 kV, and flow rate of 100 for 3 minutes. We used ITO glass as substrates. The FTIR spectra showed a successful synthesis of PVA/PEG/TiO2 fibers. This is indicated by the appearance of the corresponding characteristics of PVA, PEG, and TiO2 bonds. The XRD patterns showed the main peaks of TiO2 as well as the diffraction peaks of PVA. We obtain that the average size of PVA/PEG/TiO2 fiber is 268.27 nm. The dielectricity of PVA/PEG/TiO2 fibers increased with the addition of TiO2 nanoparticles. In addition, the increase of frequency effect to the decreased of dielectric constant. The toxicity test of PVA/PEG/TiO2 fibers showed that the samples were non-toxic. On the other hand, the result of the anti-bacterial analysis showed that the samples had no anti-bacterial properties against S. aureus bacteria.

Synthesis of TiO2 nanoparticles and TiO2-Zeolite composites and study of optical properties and structural characterization

TiO2 is a semiconductor used in photocatalysis due to its optical and electrical properties, while Zeolites are used as photocatalysts due to its porous structure that allows adequate adsorption by combining these compounds advanced materials are created. In this work, TiO2 nanoparticles and TiO2-Zeolie compounds are synthesized by the sol-gel method. The composite structure is confirmed by using XRD, FTIR and Raman. UV–vis test is used for investigation of TiO2 and TiO2-Zeolite optical properties. The EDS, SEM and TEM techniques are used for synthesized nanocomposite morphology investigation. The results exhibit that TiO2-Zeolite optical properties increases with the incorporation of Zeolite in TiO2.

In vitro antimalarial activity of synthesized TiO2 nanoparticles using Momordica charantia leaf extract against Plasmodium falciparum

Malaria is a serious global health challenge, and it has infected millions of people worldwide. There is an urgent need for new antimalarial drugs and drug targets for both prophylaxis and chemotherapy. In the present study, we biosynthesized TiO2 nanoparticles (NPs) using the Momordica charantia leaf aqueous extract as a reducing and stabilizing agent. TiO2 NPs were characterized by UV, XRD, FTIR, HRTEM, EDX, DLS and Zeta-potential. The maximum activity of mosquitocidal was observed in the synthesized TiO2 NPs against Anopheles stephensi Liston (Diptera: Culicidae) larvae and pupae, LC50 were 2.50 mg/l (I instar), 2.86 mg/l (II), 3.29 mg/l (III), 3.43 mg/l (IV), and 5.04 mg/l (pupa). The antimalarial activity of M. charantia leaf aqueous extract and TiO2 NPs were evaluated against CQ-resistant (CQ-r) and CQ sensitive (CQ-s) strains of Plasmodium falciparum. IC50 of M. charantia leaf aqueous extract were 83.64 μg/ml (CQ-s) and 88.14 μg/ml (CQ-r). Synthesized TiO2 NPs achieved IC50 of 53.42 μg/ml (CQ-s) and 59.71 μg/ml (CQ-r). The TiO2 NPs did not exhibit any noticeable toxicity on Poecilia reticulata after 24h of exposure. Overall, our results suggest that the synthesized TiO2 NPs may be employed to develop newer and safer agents for malaria control.

Surfactant effect on phase-controlled synthesis and photocatalyst property of TiO2 nanoparticles

The influence of surfactant type on phase-controlled synthesis of titanium dioxide (TiO2) was investigated by varying pH, temperature and method. Typical anionic, cationic and nonionic surfactants (SDS, CTAB and TritonX-100) with the two methods of hydrothermal and emulsion preparation were selected. The phase composition and size of synthesized TiO2 nanoparticles were characterized by XRD and FE-SEM, respectively. The photocatalytic activity of synthesized TiO2 was investigated by methylene blue (MB) degradation. Moreover, BET was used to measure the specific surface area for more understanding of the photocatalytic performance using synthesized TiO2 catalyst. Results indicated the stability, size, and shape of surfactant micelles were the main factors to determine TiO2 phase. Anatase phase was found when the micelle was small and stable. On the other hand, rutile phase occurred when the micelle lost stability and expanded in size, leading to more TiO2 aggregation around micelle. The pure anatase and pure active site rutile {1, 1, 1} TiO2 with smaller nanoparticles exhibited more effective MB photodegradation overall, although mixed phase samples showed higher degradation per unit BET area. The greater the anatase phase formed in the mixed phase TiO2, the greater the MB degradation. The highest degradation of the mixed phase was at the optimum ratio of two phases according to the synergistic effect. From this study, photocatalytic activity was affected by all factors so that one needed to consider simultaneously phase, synergistic effect of mixed phase and particle size. No one factor was deemed the most effective.

Removal of antibiotic from aqueous solution using synthesized TiO2 nanoparticles: characteristics and mechanisms

We investigated the removal of cefixime antibiotic (CEF) from aqueous solution using TiO2 nanoparticles (TiO2-NPs) in the present study. The TiO2-NPs, which were successfully synthesized using sol–gel method, were characterized by X-ray diffraction, scanning electron microscopy and Fourier transformation infrared spectroscopy (FT-IR) techniques. The removal of CEF using synthesized TiO2-NPs as a photocatalyst with ultraviolet (UV) light was evaluated by the UV spectroscopic method. The optimum parameters for removal of CEF using TiO2-NPs such as contact time, pH of solution, initial concentration of CEF and dosage of TiO2-NPs were systematically studied and found to be 90 min, 6.0, 80 ppm and 0.1 mg/mL, respectively. The degradation efficiency of about 90% was achieved under the optimum conditions. Experimental kinetic results, which were fitted by the pseudo-second-order model, were much better than with pseudo-first order. The changes in surface charge of TiO2-NPs and surface functional groups were evaluated by zeta potential measurements and FT-IR, respectively. Based on UV spectroscopy, FT-IR spectroscopy and zeta potential measurements, we demonstrate that the removal mechanism of CEF is photocatalytic degradation by TiO2-NPs catalysis than adsorption of CEF onto TiO2.

Solvothermal Synthesis of TiO<sub>2</sub>-Modified Hydroxyapatite Using Water-Isopropanol Solution

We synthesized TiO2 nanoparticles dispersed hydroxyapatite (TiO2-modifed HAp) by solvothermal treatment of α-tricalcium phosphate (α-TCP) using water-isopropanol solution including tetraisopropyl orthotitanate (TTIP). Rod-shaped HAp with TiO2 nanoparticles were formed by solvothermal treatment. HAp formation decreased with increasing the isopropanol fraction in the solution with TTIP. With increasing the treatment period, the rate of HAp formation in sample increased. The aspect ratio of HAp decreased with increasing the isopropanol fraction in the solution. Synthesized TiO2-modifed HAp samples shows the photocatalytic decoloration of methylene blue under UV irradiation.

Synthesis of anthraquinone-capped TiO2 nanoparticles using R. emodi roots: preparation, characterization and cytotoxic potential

Rheum emodi is a Himalayan herb of family Polygonaceace, known for its medicinal properties owing to the presence of chrysophanol, emodin, physcion, aloe emodi anthraquinones as major constituents. The present investigation aims to synthesize TiO2 nanoparticles (TiO2 NPs) using R. emodi root extract. The synthesized nanoparticles were characterized using UV–Vis, FTIR, FESEM, EDX, AFM, TEM and XRD techniques. UV–visible spectra indicated the surface plasmon resonance (SPR) at 336 nm. The size distribution profiles were analyzed through XRD which revealed the crystalline nature of nanoparticles with average size of 45 nm. TEM and SEM micrographs showed that the particles are spherical and uneven. FTIR spectra reflected the evidence of the presence of anthraquinones, possible bio-molecules responsible for stabilization, reduction and capping of TiO2 NPs. The cytotoxic potential of TiO2 NPs was tested against liver cancer cells (HepG2) lines which was found very effective and the formulation can be used in nano-drug to treat cancer cells in future.

The effects of metal doped TiO2 and dithizone-metal complexes on DSSCs performance

Different metal (Fe, Ni, Co or Zn) doped TiO2 nanoparticles and dithizone-metal (Fe, Ni, Co or Zn)-gallic acid complexes were prepared and used in dye sensitized solar cells (DSSCs). The TiO2 and metal doped TiO2 nanoparticles were synthesized by microwave assisted hydrothermal method. Synthesized TiO2 nanoparticles were characterized with SEM, EDS, XRD and DRS. Prepared dithizone-metal-gallic acid complexes were characterized via UV–Vis and FTIR techniques. Photoanode of DSSC was prepared with TiO2 or metal doped TiO2 coating on FTO-glass using spin coater. The dithizone and dithizone-metal-gallic acid complexes were adsorbed on bare TiO2, and dithizone or N719 were adsorbed on metal doped TiO2. Then, sandwich type DSSCs were prepared and electrochemical characterization of DSSCs was made. When the N719 and dithizone sensitized metal doped TiO2 nanoparticles were compared with undoped TiO2, Fe doped TiO2 gave lower efficiency, Ni, Co and Zn doped TiO2 gave higher efficiency than that of undoped TiO2. Co doped samples showed the highest efficiencies with both N719 and dithizone. Co doped TiO2 which was sensitized with dithizone gave nearly three times more conversion efficiency than undoped TiO2. These results show that doping procedure can enhance binding dyes to semi conductor surface. In summary, various metals show different characteristics when doped to TiO2 nanoparticles.

Effects of preparation parameters on low temperature formation of TiO2 photocatalysts

The wastewater containing organic pollutants is becoming a worldwide public health issue. Photocatalysis is a promising technology for the degradation of various organic compounds in wastewater treatment and environmental pollution reduction. Most photocatalysts cannot be widely applied due to their poor photo-response in the visible light region, complexity in preparation and difficulty in recycling. Here, we suggest a facile and modified sol–gel method to synthesize TiO2 nanoparticles at a low temperature. X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), FT-IR spectra, and UV–Vis diffuse reflectance spectra were used to investigate the effects of temperature, heat preservation time, and water amount on the crystal structure, the morphologies, and the properties of the samples. That the sample with ratio of the Ti/H2O mol at 1:3 and dried at 180 °C for 6 h showed the most satisfying photocatalytic activity. The average size of this obtained sample was 4.6 nm, the specific surface area was 241.3817 m2/g, and the band gap was 1.84 eV. The reaction rate constant for the methylene orange degradation under visible light irradiation reached 0.09713 min−1 after 60 min.