TiO2 Nanopowders Research Articles

Copper-/Zinc-Doped TiO2 Nanopowders Synthesized by Microwave-Assisted Sol–Gel Method

Using the microwave-assisted sol-gel method, Zn- and Cu-doped TiO2 nanoparticles with an anatase crystalline structure were prepared. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent and ammonia water as a catalyst. Based on the TG/DTA results, the powders were thermally treated at 500 °C. XRD and XRF revealed the presence of a single-phase anatase and dopants in the thermally treated nanoparticles. The surface of the nanoparticles and the oxidation states of the elements were studied using XPS, which confirmed the presence of Ti, O, Zn, and Cu. The photocatalytic activity of the doped TiO2 nanopowders was tested for the degradation of methyl-orange (MO) dye. The results indicate that Cu doping increases the photoactivity of TiO2 in the visible-light range by narrowing the band-gap energy.

Photocatalytic Performance of Sn–Doped TiO2 Nanopowders for Photocatalytic Degradation of Methyl Orange Dye

The tin-doped TiO2 powders obtained by sol-gel and microwave-assisted sol-gel methods were investigated. The synthesis took place in a basic medium (pH 10, ammonium hydroxide, 25%) starting from tetrabutyl orthotitanate in its parental alcohol. In the case of the dopant, Tin(II) 2-ethylhexanoate as SnO2 precursor was used in the amount of 1, 2, or 4 mol % SnO2. Based on thermal analysis data, the powders were thermally treated in air, at 500 °C. The comparative investigation of the structure and morphology of the nanopowders annealed at 500 °C was performed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy with selected area electron diffraction (HRTEM/SAED), scanning transmission electron microscopy (STEM) coupled with EDX mapping, Fourier transmission infrared (FTIR), UV–Vis, Raman and photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and X-ray florescence spectroscopy (XRF). The obtained materials were tested for the photocatalytic removal of methyl orange dye from aqueous solutions. High degradation efficiencies (around 90%) were obtained by Sn doping after 3 h of UV light irradiation.

Effectiveness of Polycarboxylate on dispersion of Nano TiO2 in concrete

The properties of Nano TiO2 (NT) have brought interest in concrete research because of the use of Nano material. The dispersion of the Nano material in concrete is one of the most traditional problems associated, the NT is one of them. The dispersion of NT significantly affects the compressive strength, flexural strength, and split tensile strength of concrete. Many researchers have adopted various techniques to enhance the dispersion of NT, this paper focuses on the study of the dispersion of NT in concrete with the use of the chemical process using a dispersing agent as polycarboxylate. In this study, the mechanical properties of concrete containing different percentages of NT have been considered. NT powder was used in ordinary Portland cement at 1, 2, and 3%, the constant water to cement (w/c) 0.38 kept same for the all mixes. The compressive strength, flexural strength, and split tensile strength increases with increase in the percentage of NT and with the use of polycarboxylate. The use of polycarboxylate (PCE) shows the improvement in the mechanical properties of concrete due to the improvement in the dispersion of NT.

Fabrication of TiO2/MXene Nanohybrid Electron Transport Layer by Artist Spray Gun Assisted Pyrolysis Method for Efficient Carbon Perovskite Solar Cell

AbstractA new class of 2D Ti3C2Tx (MXene) in different weight percentages (0, 1, and 2 wt.%) are hybrid with TiO2 nanopowder to form TiO2/MXene nanohybrids by artist spray gun assisted (ASG) pyrolysis method to use an electron transport layer (ETL) for carbon perovskite solar cell (PSC). The influence of Ti3C2Tx on TiO2 in light absorption, charge separation and carrier dynamics is studied in detail. The formation of TiO2/MXene is studied by X‐ray diffraction analysis. The emission spectrum, charge separation and carrier dynamics of TiO2/MXene nanohybrid are analyzed by photoluminescence studies. They exhibit an emission spectrum at 390 nm. The photoluminescence and electrochemical impedance results reveal that the Ti3C2Tx nanosheets provide a superior charge transfer path with less electron transfer resistance at the ETL/perovskite interface, which lead to produce higher photocurrent. This study reveals that TiO2/MXene nanohybrid can be used as a promising ETL to enhance the photo‐conversion efficiency of carbon PSC. These results reveal that TiO2‐ MXene (1 wt.%) nanohybrid ETL shows the highest PCE of 5.15% than that of TiO2‐ MXene (2 wt.%) nanohybrid ETL and pristine TiO2 ETL‐based PSC (4.64%).

Zeolite Na-A supported TiO2: Effects of TiO2 loading on structural, optical and adsorption properties

Zeolite Na-A supported TiO2 nanopowders were synthesized via a modified sol–gel technique and the effects of TiO2 loading were characterized for thermal, structural, morphological, optical and textural behaviour. Thermal properties predicted a minimum annealing temperature of 600 °C whereas the X-ray diffraction (XRD) patterns indicated that the composite was highly crystalline, and consisted of both TiO2 and zeolite Na-A peaks. Scanning electron microscopy (SEM) images confirmed that the TiO2 nanoparticles occurred mainly on the surface of the zeolite Na-A support. Nitrogen adsorption–desorption studies portrayed increased porosity and larger surface area for TiO2/zeolite Na-A compared to pure TiO2. The optical band gap decreased with increased TiO2 loading from 3.17 to 2.85 eV. The synthesized nanopowders were applied in photocatalytic dye removal, where by the highest degradation rate for the supported TiO2 was realized at 1.5 %TiO2/zeolite Na-A loading. It was found that loading beyond 1.5 %TiO2 led to a structural collapse and decline in the photodegradation rate.

The development of sulfonated polyether ether ketone (sPEEK) and titanium silicon oxide (TiSiO4) composite membranes for DMFC applications

This work aims to develop composite membranes based sPEEK polymer matrix with TiSiO4 for direct methanol fuel cell (DMFC) applications. The sPEEK having 53% of degree of sulfonation (DS) was preferred to avoid dissolution and high-swelling problems of the polymer matrix at the operating conditions. The various content of TiSiO4, prepared by the calcination reaction of TiO2 and SiO2 nano-powders, was placed into the sPEEK matrix using the solution-casting method. The thermal and physicochemical properties of the composite membranes were characterized. AC impedance spectroscopy and methanol diffusivity measurements were conducted to determine the fuel cell characteristics of the membranes. The composite sPEEK membrane with 2.5 wt% TiSiO4 performed the highest single-cell DMFC test performance compared with sPEEK and Nafion™ 117 membranes. It can be concluded that the composite sPEEK membranes with TiSiO4 can be promising and low-cost alternative membranes for DMFC applications.

Photocatalytic Testing Protocol for N-Doped TiO2 Nanostructured Particles under Visible Light Irradiation Using the Statistical Taguchi Experimental Design

The primary objective of this research is to propose and compile a specific protocol for photocatalytic measurements of modified TiO2 particles under visible-light irradiation. Nitrogen-modified titanium dioxide (N-TiO2) powder was synthesized by the sol–gel method and characterized by X-ray Diffraction Analysis (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy (micro-Raman), and Ultraviolet–visible Spectroscopy (UV-Vis). Photocatalytic tests were performed on a specially designed photocatalytic batch reactor to test the ability of the powder to degrade hazardous toxic compounds. Via the Taguchi method, nine experiments (L9) were compiled to examine the factors that affect the photocatalytic activity of the nano-sized powder. The N-TiO2 particles were characterized by the dominance of the crystalline anatase phase, exhibiting crystals in the nano-scale. The Taguchi method was designed to control four selected parameters (pollutant selection among azo dyes, amount of catalyst to pollutant, distance of the photocatalytic cell from the radiation source, and time protocol) with three levels/options each. Conclusions were drawn regarding the way each parameter affects the final degradation of the pollutant. The parameter that proved to affect the degradation of the pollutant to a greater extent was the choice of pollutant, followed by the amount of catalyst. The other two factors almost slightly affect the process, with a similar percentage. Taking into account the abovementioned results, a photocatalytic protocol for testing TiO2 nano-powder activity under visible light irradiation is proposed by using a batch, horizontal, rectangular, vis-LED equipped reactor with reflective walls.

Enhanced mechanical and photocatalytic performance of cement mortar reinforced by nano-TiO2 hydrosol-coated sand

This study investigated the impact of natural sand supported nano-TiO2 hydrosol (TiO2@Sand) on the mechanical and photocatalytic performance of cement mortar and the underlying mechanisms. The incorporation of TiO2@Sand in cement mortar (TiO2 was 0.6 wt% of cement) improved 28-day compressive strength by 67% compared with the one without nano-TiO2. Various beneficial changes towards improved mechanical strength were also observed in TiO2@Sand cement mortar: reduced total porosity by 35%, densified interfacial transition zone (ITZ) microstructure, enhanced modulus of ITZ by 54%, reduced ITZ thickness by 40% and improved dispersion of TiO2. The degradation efficiency of Rhodamine B and NO by TiO2@Sand reinforced mortar was 40% and 25% higher than cement matrix with conventionally dispersed nano-TiO2 powder, respectively. The significantly enhanced photocatalytic activity of the TiO2@Sand mortar was attributed to the expanded light absorption range, the reduced recombination of electron-hole pairs of TiO2@Sand, and the better dispersion of nano-TiO2 in cement matrix. These results demonstrated the promising potential of using TiO2@Sand in cement mortar to deliver significant enhancement of both mechanical strength and photocatalytic activity.

Photocatalytic Activity of Defective TiO2-x for Water Treatment/Methyl Orange Dye Degradation

This study is designed to highlight photocatalytic activity of TiO2 nanoparticles in methyl orange (MO) dye degradation. Titanium dioxide TiO2 nanopowder was synthesized by conventional sol-gel method and calcined in air atmosphere at different temperatures 350C, 550C and 850C. The prepared TiO2 nanoparticles then were subjected to a solid state reaction with calcium hydride (CaH2) at the same temperatures but calcined in argon atmosphere. X-Ray Diffraction (XRD) measurements used for phase and crystalline size identification showed that the obtained samples have the same TiO2 anatase phase, but the crystalline size decreased after reduction treatment. The electronic properties obtained via UV spectroscopy showed the decrease in calculated energy gap from 3.3 eV for prepared TiO2-550 to 2.65 eV for reduced TiO2-CaH2-550, which extend the absorption spectra toward visible light region. Energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) measurements revealed that the particle size decreased after reduction treatment similar to the XRD crystalline size. EDS results indicated that the deficient in oxygen content relates to formation oxygen vacancies responsible for nonstoichiometric TiO2-x oxides formation. The synthesized reduced TiO2 showed an excellent photo-catalytic activity in methyl orange dye degradation under optimum condition: pH 4.5, 40 mg catalyst loading and 10 ppm initial dye concentration.

Structure and thermal behavior of CeO2 and TiO2 nanopowders doped with noble metals

Structure and thermal behavior of CeO2 and TiO2 nanopowders doped with noble metals

STUDY OF THE MICROSTRUCTURE AND PHASE FORMATION IN CERAMICS BASED ON Zn, Sn AND Ti OXIDES

Ceramics was obtained from the mixture of ZnO, SnO2 and TiO2 nanopowders by the method of solid-state sintering at 1123 K and 1443 K. The indicated nanopowders are used as components in arc dampers and for dispersion-strengthening in silver-based electrical contact materials. The phase formation and microstructure of the obtained material were studied by the methods of scanning electron microscopy, energy dispersive microanalysis and X-ray phase analysis. It is shown that at a sintering temperature of 1123 K a dispersed structure was formed, with the size of the Zn2TiO4 and ZnO phases being 0.5 – 1.0 µm. The solid phase reactions in the system ZnO/TiO2 at Тsint = 1123 K resulted in the formation of two-phase ceramics ZnO/Zn2TiO4 with the residual amounts of the phases of zinc and tin oxides. At Тsint = 1443 K there occurred the grain growth, Zn2SnO4 became the predominant phase and there remained a certain amount of the zinc and tin oxide phases.

Hydrothermal preparation of oxide (Ga2O3, ZnO, TiO2) and derivative nanoparticles

A brief review of our recent research on preparation and characterization of oxide nanoparticles and their derivatives by hydrothermal growth is presented. A series of Ga2O3 , ZnO, and TiO2 nanoparticles, as well derivative nanomaterials including GaN nanowires and ZnO/TiO2 nanocompostes have been prepared. Ga2O3 and ZnO nanopowders have been produced using metal nitrate hydrates as precursors, while Titanium isopropoxide was used for preparation of TiO2 nanopowders. GaN nanowires have been produced by nitridation of Ga2O3 nanomaterials. The produced nanomaterials have been characterized scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy. Ga2O3 nanoparticles doped with Eu3+ ions have been characterized by photoluminescence spectroscopy in order to assess their prospects in developing nanophosphors materials.

The Influence of the Calcination Time on Synthesis of Nanomaterials with Small Size, High Crystalline Nature and Photocatalytic Activity in the TiO2 Nanoparticles Calcined at 500 °C

The development of new materials with diverse applications that fit well in the context of the current economy, where energy issues abound, is paramount. The goal of this study was to generate materials with high photocatalytic properties, at low cost and with less energy, and without health and ecological risks. Such materials would allow for a form of sustainable development that respects nature. This study investigated the influence of calcination time on titanium dioxide nanoparticles (TiO2 NPs) produced by green synthesis using Aloe vera leaf extract under a constant temperature of 500 °C. The interaction between synthesis conditions like calcination time and the size of nanoparticles produced in relation to changes in photocatalytic activity were analyzed and discussed. The results showed that when calcination was increased at 500 °C, the synthesis of small-diameter nanoparticles was promoted. TiO2 were 23 ± 2 nm (D1) and 83 ± 5 nm (D2) after 5 h and 1 h of calcination, respectively. Moreover, the calcination duration promoted an increase in crystalline nature. In the same way, the level of reduction of azo dye Remazol Red Brilliant F3B (RR180) increased when calcination time increased, and therefore, changed the optic and photo-catalytic properties of the TiO2 nanomaterial. In addition, TiO2 nanopowders (size 23 ± 2 nm) had the higher efficiency in photodegradation (100%) of dye RR180 under visible light irradiation for 60 min for up to one hour duration, but TiO2 NPs (83 ± 5 nm) had the higher efficiency (100%) for up to two hours duration.

Kinetic investigation of invigorated photocatalytic performance of phytogenically prepared Ag@TiO2 composites

The research work presented in this report focuses on a facile phytogenic process for fabrication of Ag@TiO2 nanocomposites with varying silver content (0.5 wt% to 7 wt%) using the extract of fennel (foeniculum vulgare) seeds. The polyphenolics found in seeds reduce the Ag + ions into Ag0 (AgNPs) and stabilize them on the periphery of TiO2 nanopowder to make a strong schottky junction between the two. The phytogenic nanocomposites (NCs) were characterized employing a range of spectroscopic and microscopic techniques. X-Ray diffraction (XRD) studies were carried out to determine structure of crystalline nanomaterials. Optical studies were examined using UV–Visible diffuse reflectance spectroscopy (UV-DRS) and Photoluminescence spectroscopy (PL). In UV-DRS, an absorption band near 450 nm was observed, verifying formation and deposition of AgNPs on TiO2 surface. Fourier transform infra-red (FTIR) studies were carried out to investigate the various interactions between different elements. Further, morphology of nanomaterials was analyzed using field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). Furthermore, X-Ray photoelectron spectroscopy (XPS) and Energy dispersive X-Ray spectroscopy (EDX) studies were executed to examine the elemental configuration and chemical state of the nanocomposites. In addition, the efficacy of phytogenic nanocomposites was explored for sunlight assisted photocatalytic decomposition of rhodamine-B (Rh-B) dye. Amongst prepared NCs, the 3 wt% Ag@TiO2 NCs exhibited outstanding photocatalytic activity. About 98.63% of Rh-B degraded in just 90 min of sunlight irradiation. Moreover, the apparent rate constants were also calculated for the photocatalytic degradation process and it has been observed that 3 wt% Ag@TiO2 NCs have 4.07 times higher photo-efficacy, compared to bare TiO2 (P-25). This invigorated photo-efficacy of phytogenically prepared Ag@TiO2 NCs was resultant from development of efficient and stable schottky contact between Ag metal and TiO2 surface.

Evaluation of Acrylonitrile Butadiene Styrene (ABS) polymer reinforced with Bi and TiO2 nanopowders for gamma and neutron shielding

Abstract 3D printer technology has recently become easily reachable technology and are used to create simple or complex structures with high-quality. Its superior advantages could also be useful on the production of effective radiation shielding materials. On this purpose, the presented work studies the gamma and neutron shielding effectiveness of Acrylonitrile Butadiene Styrene (ABS) sample, a 3D printing material, reinforced with Bi and TiO2 nanopowders at various gamma and neutron energies. The gamma shielding properties were evaluated using experimental (High Purity Germanium detector system), theoretical (WinXCOM computer program) and simulation techniques (GEANT4 and FLUKA) in a wide gamma energy region ranging from 59.5 to 1332.5 keV. The investigation on neutron attenuation capabilities of the printed composites were performed with help of simulation and theoretical approaches for various sample thickness and neutron energies. The half value layer of ABS-Bi10 sample is found to be as 4.9565 cm, which is much smaller than some commercial polymers: polyvinylidenechloride, polyamide, polyacrylonitrile, polyphenylenesulfide, and unsaturated polyester. With the usage of 3D printing technology, significant enhancements in neutron and gamma shielding were reported.

Role of a novel cationic gemini surfactant (CGS) on a one-step sol-gel process and photocatalytic properties of TiO2 powders.

TiO2 nanoparticles were prepared using a sol-gel process in combination with a novel cationic gemini surfactant (CGS) with amide functional groups at low temperatures. Titanium (IV) isopropoxide (TIP) and CGS were used as the starting materials and as effective agents, respectively, to orient the nanoparticles during the sol-gel synthesis. To reveal both the structural and morphological properties of the nanopowders prepared in this work, they were characterized using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area apparatus. The pore volume and pore size were calculated using the Barrett-Joyner-Halenda (BJH) model on the desorption branch. The experimental results show that the surface area and average crystallite size of the obtained TiO2 nanopowders vary between 160-203 m2/g and 27-49 nm, respectively. It was observed that the N2 adsorption-desorption isotherms for almost all samples of TiO2-X% CGS (X: mass of CGS) show the typical Type I with a hysteresis loop of H4. The photocatalytic activities of the CGS-modified nanocomposites are evaluated not only by the photocatalytic degradation of methyl orange (MO) but also by the reduction of Cr(VI) as model pollutants in the presence of visible light.

Test of conductor and semiconductor electrocatalysts in high voltage alkaline electrolyzer as production media for green hydrogen

Despite the restricted success of conductor and semiconductor electrodes in solving hydrogen production problems, they provide a promising alternative to expensive conventional electrodes in water electrolysis investigations. Titanium dioxide (TiO2) and silver (Ag) are widely used as photocatalysts in water splitting systems for hydrogen generation. Though TiO2 is an inactive chemical semiconductor with poor conductivity, it has not been entirely investigated as an electrocatalyst yet. Two criteria were used to achieve this target: supplying high voltage to overcome the TiO2 large band gap and immersing it in an alkaline solution to activate its inert surface. For comparison study, Ag noble metal nanoparticles coating was employed as a competitive electrocatalyst. In this regard, the application of Ag and TiO2 coated on Ti electrodes in a hydrogen production system operated under high voltage was reported. The nanoparticles were synthesized using cost-effective and simple methods based on UV-deposition for Ag nanoparticles and the chemical precipitation method for TiO2 nanoparticles. Then the synthesized nanoparticles were deposited on the Ti electrodes by simple immersion. The synthesized nanoparticles and coated electrodes were tested by XRD, SEM, and EDS to study their morphology, structure, particle size, and surface composition. Based on these results, TiO2 nano-powder and coated electrodes exhibited homogenous spheres with a mixture of rutile and anatase phases, the majority being the anatase phase. The Ag-coated Ti substrate possessed a smaller crystallite size compared to TiO2 coated substrate. To evaluate the performance of Ag/Ti and TiO2/Ti electrodes toward hydrogen production, H2 flow rates were measured in a 3.6 M KOH electrolytic solution at 6 V. Hydrogen flow rates obtained for pure Ti, Ag, and TiO2 electrodes at a steady state were 21, 35, and 37 SCCM (standard cm3/min), respectively. Also, it was found that energy consumption was reduced when the electrodes were coated with nanoparticles. Furthermore, the electrolyzer's performance was assessed by calculating the hydrogen production efficiency and the voltage efficiency. The results showed that using TiO2 electrodes gave the best hydrogen production and voltage efficiencies of 27% and 23%, respectively. This study brings new insights about Ag and TiO2 coated electrodes in alkaline water electrolysis at high voltage regarding nanoparticle performance, hydrogen production, system performance, and energy consumption. In addition, minimizing the fabrication and operation costs of hydrogen production is the major enabler for the broad commercialization of water electrolysis devices.

Ultrasonication-aided photocatalytic degradation of polyethylene

This study is focused on the development of green method for the photocatalytic degradation of polyethyelene (PE), a major constituent of plastic waste. The method developed in this study includes ultrasonication of PE pieces along with TiO2 Nano powder (NP). The samples were than exposed to UV light for photocatalytic degradation, where weight loss study was perform to check weight loss (percentage) with respect to time. 56 % weight loss was the highest weight loss achieved among all samples when exposed for 504 h. The photocatalytic degraded samples were than characterized by scanning electron microscopy, where formation of cavities due to photocatalytic degradation were observed. The change in surface chemistry of the samples was analyzed by Fourier transform infrared spectroscopy (FTIR) which show a prominent photodegradation happened on the PE surface, ultrasonicated with TiO2 NP whereas, no change in surface chemistry was observed for samples without TiO2 NP.

Effect of nano-TiO2 addition on the microstructure and erosion-corrosion behavior of Ti(C,N)-based cermets fabricated by in-situ carbothermal reduction

Ti(C,N)-based cermets with partially adding nano-TiO2 powders were fabricated via in-situ carbothermal reduction. The effects of nano-TiO2 additions on the microstructure, mechanical properties and erosion–corrosion resistance of the cermets were studied. The microstructure of the cermets principally consisted of white-core grains and those with non-typical core-rim phase. Furthermore, the addition of nano-TiO2 could refine the grain size. The comprehensive mechanical properties decreased and then increased with the substitution of nano-TiO2 particles. The influences of various nano-TiO2 contents on the erosion-corrosion resistance were analyzed in acid solution. Erosion-corrosion resulted in the loss of the nickel binder and the exfoliation of grains. The surface corrosion morphology indicated that the erosion-corrosion resistance of Ti(C,N)-based cermets was strengthened by adding nano-TiO2. Overall, the cermet with complete addition of nano-TiO2 showed the significantly improved comprehensive mechanical properties and superior erosion–corrosion resistance.

Photocatalytic and Antibacterial Properties of Doped TiO2 Nanopowders Synthesized by Sol-Gel Method.

For environmental applications, nanosized TiO2-based materials are known as the most important photocatalyst and are intensively studied for their advantages such as their higher activity, lower price, and chemical and photoresist properties. Zn or Cu doped TiO2 nanoparticles with anatase crystalline structure were synthesized by sol−gel process. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent, and a hydrolysing agent (ammonia-containing water) was added to obtain a solution with pH 10. The gels were characterized by TG/DTA analysis, SEM, and XPS. Based on TG/DTA results, the temperature of 500 °C was chosen for processing the powders in air. The structure of the samples thermally treated at 500 °C was analysed by XRD and the patterns show crystallization in a single phase of TiO2 (anatase). The surface of the samples and the oxidation states was investigated by XPS, confirming the presence of Ti, O, Zn and Cu. The antibacterial activity of the nanoparticle powder samples was verified using the gram−positive bacterium Staphylococcus aureus. The photocatalytic efficiency of the doped TiO2 nanopowders for degradation of methyl orange (MO) is here examined in order to evaluate the potential applications of these materials for environmental remediation.