Anatase-rutile Phase Transformation Research Articles

Structural, chemical, optical and photocatalytic properties of Zr co-doped anatase-rutile mixed phase TiO2: Ag nanoparticles

Zr co-doped TiO2:Ag nanoparticles were synthesized by the co-precipitation method and the influence of Zr co-dopant with varying content on the structural, optical and photocatalytic properties of TiO2:Ag photocatalysts was investigated. X-ray diffraction and Raman spectroscopy confirmed the anatase-rutile mixed phase of TiO2 and Zr content eased the anatase-rutile phase transformation. X-ray diffraction peak shift with Zr content indicated the substitutional doping of Zr4+ ions into TiO2 lattice. The optical properties of the nanoparticles were investigated with diffuse reflectance spectroscopy, photoluminescence and Fourier transform infrared spectroscopy. Zr dopants induced the Burstein-Moss effect, resulting in the broader bandgap and photoluminescence shift. X-ray photoelectron spectroscopy was utilized to reveal the surface chemical environment of the Zr co-doped TiO2:Ag nanoparticles and found the presence of Zr4+ ions on the photocatalyst surface, which act as electron traps. The dependence of operational parameters such as photocatalytic load, dye concentration and pH on Zr co-doped TiO2:Ag nanocatalyst was also monitored. The photocatalysts demonstrate improved photocatalytic activity toward methylene blue degradation with maximum efficiency achieved by the photocatalyst having the highest Zr content. 20 mg and 10.35 μM were found to be the optimum values for photocatalytic load and initial methylene blue concentration, respectively. Further, at alkaline pH, complete decolorization of the reaction mixture was observed in only 60 min with 92.6% efficiency by highest co-doped photocatalyst. The effect of Zr content on degradation rate with different parameters was also explored with a possible mechanism to understand the effect of dopants on photocatalytic activity of the photocatalysts.

Catalytic behavior of gold nanoparticles supported on a TiO2-Al2O3 mixed oxide for CO oxidation at low temperature.

The present work highlights the versatility of a TiO2-Al2O3 mixed oxide bearing highly dispersed gold nanoparticles that was applied in the CO oxidation reaction at room temperature. The TiO2, Al2O3, and TiO2-Al2O3 supports were synthesized by the sol-gel method, while gold nanoparticles were added by the deposition-precipitation with urea method using a theoretical Au loading of 2 wt.%. A promotional effect of the TiO2-Al2O3 support on the activity of gold catalysts with respect to TiO2 and Al2O3 was observed; Au/TiO2-Al2O3 showed outstanding CO oxidation, being active from 0°C and stable throughout a 24-h test. As for the alumina content (5, 10, and 15 wt.%) in TiO2, it improved the textural properties by retarding the crystal growth and anatase-rutile phase transformation of TiO2, suppressing the deposition of carbon on the catalyst surface and stabilizing the Au nanoparticles even at high temperatures. Gold was highly dispersed with nanoparticle sizes ranging from 1 to 2nm when H2 was used to treat thermally the Au/TiO2-Al2O3, Au/TiO2, and Au/Al2O3 materials. In addition, the XPS technique helped elicit that Au0 and Au1+ boosted their interaction with the TiO2, Al2O3, and TiO2-Al2O3 supports by means of charge transfer, which resulted in outstanding CO oxidation activity from 0°C. Likewise, the key factors that control the peculiar catalytic performance in the CO oxidation reaction are discussed, which represents a step forward in the versatility behavior of gold catalysts supported on mixed oxide catalysts.

The effect of pH on the physical and structural properties of TiO2 nanoparticles

The present study prepared TiO2 nanoparticles using the sol–gel method with solutions of various pH values (1.5, 4.5, 7.5 and 10.5). The structural, morphological and optical properties of the prepared TiO2 nanoparticles were analyzed. A mixture of anatase–rutile phase was obtained with nanoparticles prepared in an acidic medium such as pH = 1.5 and 4.5. A pure anatase phase was obtained with nanoparticles prepared in an alkaline medium such as pH = 7.5 and 10.5. The average crystallite size was calculated for the prepared nanoparticles. The crystallite sizes decreased with increased pH values. The band gaps of the prepared nanoparticles were calculated. The band gap value of the sample with a limit pH value of 4.5 for anatase–rutile phase transformation was calculated to be 3.89 eV for direct transitions and 3.68 eV for indirect transitions.

Highly sensitive humidity sensor based on the solid solution Zr0.2Ti0.8O2 nanofibers

The ZrxTi1−xO2 (x = 0.0–0.5) nanofibers were synthesized by an electrospinning process. The influences of zirconium incorporation on the structure, phase composition, lattice parameters, morphology, specific surface area, and surface states were investigated in terms of XRD, SEM, BET, and XPS tests. The humidity sensing performances were also carried out in detail. It can be concluded that the replacement of Zr at Ti-site had significant impacts with regard to the phase structure: the anatase-rutile phase transformation was inhibited by Zr4+ ion doping; Zr4+ ion was successfully incorporated into the TiO2 lattice through a substitutional mode resulting in the formation of solid solution ZrxTi1−xO2 (x = 0.1–0.2) with anatase structure; when the Zr4+ ion was saturated, excessive Zr4+ ion formed new phase of Ti2ZrO6 and ZrTiO4 (nominal x ≥ 0.3); the lattice parameters and the cell volume increased as Zr4+ ion incorporation. The solid solution Zr0.2Ti0.8O2 nanofibers had the highest Ti3+ abundance among the samples with x ≤ 0.2, accompanied by the highest oxygen vacancies. Moreover, the solid solution Zr0.2Ti0.8O2 nanofibers exhibited the best humidity sensing properties: excellent sensitivity as proven by four orders of magnitude change to impedance at 11–95% relative humidity (RH), negligible hysteresis, rapid response and recovery speed as well as superior stability, which were induced by high concentration of oxygen vacancies combined with reactive Ti3+ ions. A detailed study of the sensing mechanism was also performed in terms of complex impedance spectra.

Development and characterization of negative air ion emitting mica- and sericite-based antimicrobial pearlescent pigments

In modern era, people are spending their time indoors around 90%. Therefore, in terms of public health, increasing indoor air quality is of great importance. In this study, it was aimed to develop pearlescent pigments that emit negative air ions in order to increase indoor air quality, and the potential of such pigments for use in composite wall paint was evaluated. For this purpose, low refractive index muscovite mica and sericite clay minerals, which were shown to emit negative ions, were combined with high refractive index TiO2. The use of two different clay minerals, different proportions of SnO2 dopant, and calcination process application were selected as experimental parameters and the effect of these parameters on the anatase-rutile phase transformation of TiO2 in the pigments was investigated. Increasing the rutile TiO2 ratio in the synthesized pigments were resulted in a better pearlescent effect and lower photocatalytic activity. In order to increase the negative air ion emitting effect of these pigments with the desired pearlescent pigment properties, these samples were also combined with extract of the Chlorophytum comosum, which also is known to emit negative air ions. As a result of the negative ion emission measurements, it was found that the samples were continued to emit negative ions without a time-dependent decrease even when not combined with the extract of C. comosum. In addition, it was showed that the prepared samples have antibacterial effect against Escherichia coli, which is abundant in indoor environments, especially in health centers such as hospitals and dispensaries, and antifungal effect against Aspergillus niger, which is known as black mold, growing on moist walls.

Surface Properties of 1DTiO2 Microrods Modified with Copper (Cu) and Nanocavities.

This work deals with Cu-modified 1DTiO2 microrods (MRs) and their surface properties. The pristine lyophilized precursor Cu_1DTiO2, prepared by an environmentally friendly cryo-lyophilization method, was further annealed in the temperature interval from 500 to 950 °C. The microstructure of all samples was characterized by electron microscopy (SEM/EDS and HRTEM/SAED), X-ray powder diffraction (XRD), infrared spectroscopy, simultaneous DTA/TGA thermoanalytical measurement, and mass spectroscopy (MS). Special attention was paid to the surface structure and porosity. The 1D morphology of all annealed samples was preserved, but their surface roughness varied due to anatase-rutile phase transformation and the change of the nanocrystals habits due to nanocavities formation after releasing of confined ice-water. The introduction of 2 wt.% Cu as electronically active second species significantly reduced the direct bandgap of 1DTiO2 in comparison with undoped TiO2 and the standard Degussa TiO2_P25. All samples were tested for their UV absorption properties and H2 generation by PEC water splitting. We presented a detailed study on the surface characteristics of Cu doped 1DTiO2 MRs due to gain a better idea of their photocatalytic activity.

Anatase–Rutile Transition and Photo-Induced Conductivity of Highly Yb-Doped TiO2 Films Deposited by Acid Sol–Gel Dip-Coating Method

A method to prepare Yb-doped TiO2 is proposed, using titanium isopropoxide and ytterbium oxide. Thin films and powders are produced through the sol–gel technique where the Yb concentrations are 0.01 at.%, 0.02 at.%, 1 at.%, 2 at.% 4 at.% and 8 at.%. The increase in the doping concentration intensifies gradually the sample transparency for the whole observed spectrum and reaches the transparency degree of the undoped sample with the highest concentration of ytterbium. By means of x-ray diffraction (XRD) we find that the solution’s pH leads to the formation of a rutile structure which is compensated for by lanthanide doping, inhibiting the anatase–rutile phase transformation. Then, the XRD profile depends on the Yb concentration, being mostly anatase for undoped and highly (8 at.%) doped samples, with mixed ratios of these two phases in other concentrations. Maintaining an acid solution leads to fewer intergrain defects in the rutile structure contributing to higher conductivity. Photo-induced investigation of 8 at.% Yb-doped thin film, using several light sources leads to distinct behavior concerning the excitation of intra-bandgap states and/or electron–hole pairs. This result helps to understand the electronic transport in Yb-doped TiO2 and shows that devices based on its conductivity may have improved performance by irradiation with controlled light energy.

Anatase-rutile phase transformation and photocatalysis in peroxide gel route prepared TiO2 nanocrystals: Role of defect states

Peroxide gel method, utilizing titanyl sulfate as a titanium source, is employed to synthesize TiO2 nanocrystals. The nanoparticles are further annealed at different temperatures of 300, 500, 700, and 900 °C. XRD analysis reveals a phase pure anatase structure for the as-prepared sample and anatase-rutile mixed-phase for annealed TiO2 nanocrystals. UV–visible diffuse reflectance and Fourier transform infrared spectroscopic measurements also confirm the formation of anatase-rutile mixed phase for annealed samples. Micro-Raman spectra recorded for three different excitation wavelengths suggest the formation of rutile phase in the interior of the anatase nanoparticles upon annealing. Photocatalytic efficiencies of the TiO2 nanocrystals are evaluated by choosing methyl orange as a model dye under UV and simulated solar irradiations. Presence of defect states, mainly oxygen vacancies, that form subband states extending from shallow to the deep levels in TiO2 bandgap are confirmed from photoluminescence measurements. Among the TiO2 samples, the nanocrystals annealed at 300 °C shows the maximum photocatalytic activity. The observed variation in the photocatalytic activities of the TiO2 nanocrystals is explained as per the difference in the intensity ratio of the emission peaks corresponding to those of shallow and deep traps in the bandgap of the TiO2 nanocrystals.

Highly efficient visible-light-driven photocatalytic degradation of VOCs by CO2-assisted synthesized mesoporous carbon confined mixed-phase TiO2 nanocomposites derived from MOFs

Improving the visible light response and efficient separation of electron-hole pairs play vital roles in commonly used TiO2 photocatalyst for VOCs degradation. Herein, N-doped mesoporous carbon encapsulated anatase-rutile phase junction TiO2 (TiO2@C-N(x)) was successfully synthesized via the pyrolysis of a representative amine functionalized Ti-based MOF, NH2-MIL-125, under the atmosphere of Ar and subsequent CO2 treatment. Our synthesis stragety was based on the rational regulation of the formation of TiO2 phase junction and the decomposition of amorphous carbon onto the TiO2@C-N (without subsequent CO2 process) using CO2 as both anatase-rutile phase transformation promoter and mild oxidant. Compared with TiO2@C-N, TiO2@C-N(x) nanocomposites with subsequent CO2 process exhibit significantly improved photocatalytic activity as well as mineralization efficiencies. For example, the mineralization efficiency reached 51.9% at 62.4% of styrene degradation within 240 min of visible-light irradiation by using the optimal TiO2@C-N(30) nanocomposites as compared with only 19.7% mineralization efficiency at 31.0% of styrene degradation under the same conditions of TiO2@C-N. Furthermore, the primary radicals involved in degradation of VOCs was identified by electron paramagnetic resonance spectroscopy, and the possible degradation intermediates were also monitored by means of proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). Finally, the radicals involved degradation reaction mechanism was also tentatively proposed.

The effect of Ti+ ion implantation on the anatase-rutile phase transformation and resistive switching properties of TiO2 thin films

We investigate here the structural phase transformation and electrical resistive switching properties of TiO2 thin films (80 nm) after their self-ion implantation with 50 keV Ti+ ions at several fluences. UV-Raman, grazing incidence x-ray diffraction (GIXRD), transmission electron microscopy, x-ray photoelectron spectroscopy, and atomic force microscopy techniques have been utilized to investigate the modifications in thin films. Both, the as-grown and ion implanted, films display mixed phases of rutile (R) and anatase (A). Surprisingly, however, a phase transition from A to R is observed at a critical fluence, where some anatase content transforms into rutile. This A to R transformation increases with additional fluence. The critical fluence found by GIXRD is slightly smaller (1×1013 ions/cm2) than from UV-Raman (1×1014 ions/cm2), indicating the first initiation of phase transformation probably in bulk. All the films contain anatase in nanocrystalline form also and the phase transformation seems to take place via aggregation of anatase nanoparticles. Thin films also show the presence of oxygen vacancies (OV) Ti3+, whose number grows with fluence. These OV as well as thermal spikes created during Ti+ ion implantation are also crucial for the A-R transition. After implantation at the highest fluence, TiO2 thin films show bipolar resistive switching behavior. The development of conducting filaments, formed by the migration of many oxygen vacancies generated during ion implantation, can be responsible for this behavior.

Shock wave induced anatase to rutile TiO2 phase transition using pressure driven shock tube

Pressure driven shock tube was employed to switch TiO2 nanoparticles from anatase to rutile phase at an applied pressure of about 2.683 MPa. The crystal structure and surface morphology of the anatase-rutile phase transformation are investigated for pre and post loaded shock using X-ray diffraction, FT – Raman spectroscopy and transmission electron microscopy respectively. The results from the experimental investigations elucidated that the TiO2 nanoparticles under post shock facilitated the formation of new crystallographic phase (rutile) from anatase phase.

The effect of heat treatment on the anatase-rutile phase transformation and photocatalytic activity of Sn-doped TiO2 nanomaterials.

Sn-doped TiO2 nanomaterials with different amounts of Sn (1, 2.5, 5, 10, and 15 at%) were prepared by a sol–gel method and characterized by XRD, TG, DTA, EDS, XPS, DRS, SEM, BET, and PL. The photocatalytic activity of the prepared samples was investigated by measuring the degradation of rhodamine B in aqueous solution under UV light. The experimental results indicate that doping with Sn promotes phase transformation from anatase to rutile. The photocatalytic activity of TiO2 is influenced by both the heat treatment temperature and the Sn doping concentration. 1% Sn–TiO2 exhibits the highest degradation rate at 350 °C and 5% Sn–TiO2 exhibits the best photocatalytic activity at 500 °C and 650 °C. The enhancement of the photocatalytic activity can be ascribed to a larger surface area and a better hydration ability, as well as less recombination of the photogenerated pairs.

Highly photoreactive TiO2 hollow microspheres with super thermal stability for acetone oxidation

TiO2 hollow microspheres (TiO2-HMSs) have attracted much attention because of their high photoreactivity, low density, and good permeability. However, anatase TiO2-HMSs have poor thermal stability. In this study, surface-fluorinated TiO2-HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2 solution at 180 °C. The effect of the calcination temperature on the structure and photoreactivity of the TiO2-HMSs was systematically investigated, which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation. We found that after calcination at 300 °C, the photoreactivity of the TiO2-HMSs decreases from 1.39 × 10−3 min−1 (TiO2-HMS precursor) to 0.82 × 10−3 min−1 because of removal of surface-adsorbed fluoride ions. With increasing calcination temperature from 300 to 900 °C, the building blocks of the TiO2-HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles, and the photoreactivity of the TiO2-HMSs steady increases from 0.82 × 10−3 to 2.09 × 10−3 min−1 because of enhanced crystallization. Further increasing the calcination temperature to 1000 and 1100 °C results in a decrease of the photoreactivity, which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at 1100 °C. The effect of surface-adsorbed fluoride ions on the thermal stability of the TiO2-HMSs is also discussed.

Electrospinning amorphous SiO2-TiO2 and TiO2 nanofibers using sol-gel chemistry and its thermal conversion into anatase and rutile

SiO2-TiO2 nanofibers were electrospun from partially hydrolyzed tetraethyl orthosilicate, and titanium isopropoxide using sol-gel chemistry. SiO2-TiO2 sol phase diagrams were created summarizing the role of composition on solution homogeneity and electrospinnability. Inorganic nanofiber spinnability was studied without the addition of any organic polymer, oligomer, gelator, or binder. TiO2 concentration within SiO2-TiO2 fibers ranged from 25 to 100mol%. SiO2, SiO2-TiO2, and TiO2 nanofiber structures were investigated using scanning electron microscopy and transmission electron microscopy. Inorganic fiber spinning was highly dependent on sol reaction temperature, time, and solution composition. At high TiO2 concentrations, twisted and ribbon-like nanofibers with dumbbell-shaped cross-sections were observed. This was attributed to jet branching and splitting during electrospinning. Electrospun fibers were amorphous at room temperature, but thermally converted into crystalline anatase, which underwent additional structural changes at higher temperatures into rutile. This anatase-rutile thermal phase transformation was highly dependent upon TiO2 concentration. Nanofiber composition, thermal stability, and crystalline structures were characterized by energy-dispersive X-ray spectroscopy; Fourier transform infrared spectroscopy, thermal gravimetric analysis, and wide-angle X-ray diffraction.

Synergistic Effects of Sm and C Co-Doped Mixed Phase Crystalline TiO₂ for Visible Light Photocatalytic Activity.

Mixed phase TiO2 nanoparticles with element doping by Sm and C were prepared via a facile sol-gel procedure. The UV-Vis light-diffuse reflectance spectroscopy analysis showed that the absorption region of co-doped TiO2 was shifted to the visible-light region, which was attributed to incorporation of samarium and carbon into the TiO2 lattice during high-temperature reaction. Samarium effectively decreased the anatase-rutile phase transformation. The grain size can be controlled by Sm doping to achieve a large specific surface area useful for the enhancement of photocatalytic activity. The photocatalytic activities under visible light irradiation were evaluated by photocatalytic degradation of methylene blue (MB). The degradation rate of MB over the Sm-C co-doped TiO2 sample was the best. Additionally, first-order apparent rate constants increased by about 4.3 times compared to that of commercial Degusssa P25 under the same experimental conditions. Using different types of scavengers, the results indicated that the electrons, holes, and •OH radicals are the main active species for the MB degradation. The high visible-light photocatalytic activity was attributed to low recombination of the photo-generated electrons and holes which originated from the synergistic effect of the co-doped ions and the heterostructure.

The Influence of Cr Doped TiO2 on the Optical Property and Photocatalytic Activity under Sunlight Irradiation

Pure TiO2 and Cr doped TiO2 (0.1-1.0wt% Cr) nanoparticles were synthesized via sol gel method. This study focuses on narrowing the TiO2 band gap energies in order to enhance the photocatalytic efficiency under visible light. The synthesized samples were characterized by X-Ray diffraction method (XRD), field emmision (FESEM) and also UV-Vis diffuse reflectance spectroscopy (DRS).The photocatalytic activity under sunlight irradiation was demonstrated by photocatalytic decomposition of methylene blue in water using UV/Vis spectrophotometer. The XRD analysis of pure TiO2 and doped TiO2 calcined at 500oC showed a mixture of anatase and rutile phases with decreasing crystallites size from 13.3nm to 11.6nm as the concentration of Cr was increased. The anatase-rutile phase transformation increased from 28.8% to 57.4%. An indication shows that at 0.75wt%, Cr the anatase and rutile phases have equal composition percentage. This study demonstrated that band gap energy of TiO2 was reduced with Cr doping which could enhance the photocatalytic efficiency. Sample containing 1.0wt% exhibit the lowest optical band gap energy at 2.86 eV. The optimum chromium doping concentration was found to be at 0.1 wt% Cr corresponding to band gap energy of 2.87 eV and degradation rate of 84%.

The Influence of Cr Doped TiO2 on the Optical Property and Photocatalytic Activity under Sunlight Irradiation

Pure TiO2 and Cr doped TiO2 (0.1-1.0wt% Cr) nanoparticles were synthesized via sol gel method. This study focuses on narrowing the TiO2 band gap energies in order to enhance the photocatalytic efficiency under visible light. The synthesized samples were characterized by X-Ray diffraction method (XRD), field emmision (FESEM) and also UV-Vis diffuse reflectance spectroscopy (DRS).The photocatalytic activity under sunlight irradiation was demonstrated by photocatalytic decomposition of methylene blue in water using UV/Vis spectrophotometer. The XRD analysis of pure TiO2 and doped TiO2 calcined at 500oC showed a mixture of anatase and rutile phases with decreasing crystallites size from 13.3nm to 11.6nm as the concentration of Cr was increased. The anatase-rutile phase transformation increased from 28.8% to 57.4%. An indication shows that at 0.75wt%, Cr the anatase and rutile phases have equal composition percentage. This study demonstrated that band gap energy of TiO2 was reduced with Cr doping which could enhance the photocatalytic efficiency. Sample containing 1.0wt% exhibit the lowest optical band gap energy at 2.86 eV. The optimum chromium doping concentration was found to be at 0.1 wt% Cr corresponding to band gap energy of 2.87 eV and degradation rate of 84%.

Highly active aggregate photocatalyst with hierarchically porous structures synthesized by using a hydroxyapatite template

Crystalline meso-/macroporous TiO2 aggregate was synthesized by using a hydroxyapatite template. The hydroxyapatite could be removed by treating it with hydrochloric acid even after it was heated at 800°C. The aggregate included macropore with sizes of 1⿿5μm in diameter and longer than 5μm in length, penetrating into the aggregate, with walls that consisted of nanoparticles. Based on the results of N2-BET and X-ray diffraction measurements, decline in specific surface area and anatase-rutile phase transformation during heating were suppressed by the addition of the hydroxyapatite. That is, the aggregate had higher specific surface area and higher anatase phase ratio than the control sample obtained without using the hydroxyapatite. Photocatalytic activity evaluated by a photo-decomposition of methylene blue dye increased with increasing heating temperature. The aggregate heat-treated at 800°C had three times higher photocatalytic activity and twenty times larger aggregate diameter than the commercial ST-01 TiO2 powder.

Investigation of Ag-TiO2 nanostructures photocatalytic properties prepared by modified dip coating method

In this article, titanium dioxide and silver nanostructures were deposited on glass substrates using modified sol–gel methods and dip-coating technique. The films were characterised chemically and physically using different techniques (TLC, UV–Vis and XRD) and tested for environmental applications regarding degradation of aromatic hydrocarbons. The photocatalytic activity of the TiO2 nanostructures is tested with different small concentrations of phenol in water and reaction mechanisms discussed. Considerable enhancement is observed in the photodegradation activity of Ag-modified (3 wt.%) TiO2 compared to unmodified TiO2 nanostructures for phenol concentrations within the pseudo-first-order Langmuir–Hinshelwood (LH) model for reaction kinetics. The pseudo-first-order global degradation rate constant increased from <0.005 min−1 for TiO2 to 0.013 min−1 for 3 mol% Ag-modified TiO2. The enhancement is attributed to the incorporation of Ag which promotes the generation of reactive oxygen species and increases the carrier recombination life-time. In addition, Ag has been observed to extend the absorption to the visible region by its surface plasmon resonances and to suppress the anatase–rutile phase transformation. Moreover, TiO2 grain size prepared was found to be 10 nm which maximises the active surface area. For phenol initial concentrations as low as 0.0002 M, saturation trend in the degradation process occurred at 0.00014 M and the reaction rate can be fitted with half-order LH kinetics.

Nanophase Changes in Nickel Doped Titania Composites by Thermal Treatment and Photocatalytic Destruction of NO(x).

This study investigated the influence of Ni doping and thermal treatment (600, 800 degrees and 1000 degrees C) on the physiochemical properties of a commercially available low cost KA100 TiO2. Ni containing KA100 samples were prepared with different loading of Ni (3%, 6% and 9% wt to KA100) and subjected to heat treatement at 600 degrees, 800 degrees and 1000 degrees C. The as-prepared samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Diffuse reflection UV-Visible spectroscopy and Raman spectroscopy and nitrogen-adsorption-desorption measurements to observe the nanophase changes in the particle characteristics following Ni modification and thermal treatment. The results show that the Ni atom entered the TiO2 lattice structure upon heat treatment at 800 degrees C and 1000 degrees C influencing the anatase-rutile phase transformation. The TiO2 powders after heat treatment had a bimodal pore-size distribution as the temperature of the heat treatment increased. In addition, the anatase crystallite size and average pore sizes increased. Photodegradation of NO(x) was investigated using the Ni doped KA100 as a photocatalyst. Modification of KA100 with nickel and heat treatment up to 1000 degrees C enhanced the photocatalysis for the degradation of NO(x). Typically, KA100 modified with 6% Ni and heat treated to 1000 degrees C exhibited excellent NO(x) removal activity.