Ions In TiO2 Research Articles

Physical properties and photocatalytic activity of Cr doped TiO2 nanoparticles.

Nanocrystalline Ti1-x Crx O2 (0≤ x ≤0.20) samples are synthesized via acid-modified sol-gel process and characterized with various techniques, such as HRTEM, FESEM, Raman, XPS, DTA and VSM. The TEM image of TiO2 exhibits elongated nanoparticles with an average size of 10 nm. The HRTEM in combination with selected area electron diffraction (SAED) patterns reveals the interplanar spacing and polycrystalline nature of the samples, respectively. FESEM micrographs reveal non-uniform morphologies and less aggregation of the particles in the doped sample. Raman spectra ensure the phase purity of the samples and a blue shift on Cr doping. X-ray photoelectron spectra (XPS) predict the chemical state of the elements and oxygen vacancies in the prepared samples. The room temperature magnetic studies reveal a significant variation in the magnetic parameters on Cr doping in TiO2 . The differential thermal analysis (DTA) shows the structural phase transition at ∼630°C. The photocatalytic performance is studied for the degradation of methylene blue (MB) dye under visible-light irradiation. A higher photocatalytic efficiency is found for the 20% of Cr-doped TiO2 . These studies propose that the appropriate incorporation of Cr ions makes TiO2 very efficient for visible light-driven photocatalysts required for applications in wastewater treatment. In the present study, nanoparticles of TiO2 and Cr doped TiO2 by a cost-effective acid-modified sol-gel process. The effect of Cr doping on the microstructure, thermal, magnetic and photocatalytic properties of TiO2 were explored in detail. The transmission electron microscopy (TEM) images exhibit the presence of elongated nanoparticles with an average size of 10 nm. Field emission scanning electron microscopy (FESEM) was used to study the surface morphology of the synthesized materials, which revealed non-uniform morphologies and less aggregation of the particles in the Cr-doped sample. Energy dispersive x-ray spectroscopy (EDS) confirms the elemental compositions with the appropriate stoichiometry of the elements. Raman spectra ensure the phase purity of the materials and also a blue shift with the incorporation of Cr ions in TiO2 . X-ray photoelectron spectra (XPS) predict the chemical state of the elements and oxygen vacancies in the prepared samples. The magnetic nature of all the synthesized samples was examined through the vibrating sample magnetometer (VSM) and revealed weak ferromagnetic behavior of the samples. These results signify that the oxygen vacancies and defects play a crucial role in developing the ferromagnetic nature of oxide semiconductors. The differential thermal analysis (DTA) shows the structural phase transition at ∼630°C. The photocatalytic performance of the prepared samples was studied for the degradation of methylene blue (MB) dye under irradiation of visible light. A higher photocatalytic efficiency was found for the 20% of Cr-doped TiO2 . These studies propose that the appropriate incorporation of Cr ions makes TiO2 very efficient for visible light-driven photocatalysts required for applications in wastewater treatment. This article is protected by copyright. All rights reserved.

Influence of Water Vapor and Temperature on the Oxide Scale Growth and Alpha-Case Formation in Ti-6Al-4V Alloy

The Ti-6Al-4V alloy is extensively used in aerospace, automotive and biomaterial applications. In the aerospace industry, the service temperature of Ti-6Al-4V is currently limited to 350 °C due to its insufficient oxidation resistance. Oxidation at higher temperatures causes the formation of a fast-growing oxide scale and an oxygen-enriched subsurface layer, which is known as the “alpha-case.” Additionally, the effect of water vapor on the oxidation behavior is critical. In the present study, the oxidation behavior of Ti-6Al-4V in dry air and air containing 10 vol.% H2O at 500, 600 and 700 °C for up to 500 h has been investigated. The main focus of this study is the examination of the different oxide scale morphologies along with the oxygen enrichment in the subsurface zone. It has been observed that spallation of the oxide scale is more severe in a water vapor-containing environment. In dry air, the oxide morphology shows the typical layered TiO2/Al2O3 structure after exposure at 700 °C for 300 h, while Al2O3 precipitates are present in the outermost part of the TiO2 scale when oxidized in wet air. This indicates that the solubility and diffusivity of Al3+ ions in TiO2 are influenced by water vapor. In addition, the extent of oxygen enrichment in the subsurface zone (alpha-case) as a function of temperature and time is determined by nanoindentation profiles. It was shown that in contrast to the scale formation, the alpha-case thickness is not affected by the presence of water vapor in the atmosphere.

Degradation of formaldehyde and methylene blue using wood-templated biomimetic TiO2

The multilevel pore structure of natural wood is an ideal template material for the synthesis of functional materials. In this study, a natural wood pore structure was introduced into the structure of titanium dioxide through a biological template synthetic strategy. The resulting structure showed improvement in the adsorption of formaldehyde and methylene blue from solution. It also manifested excellent photocatalytic performance under visible light. The results of photocatalytic degradation illustrated that wood-templated titanium dioxide degraded 71.8% of the formaldehyde in solution within 100 min under visible light. In addition, the efficiency of methylene blue (MB) degradation was as high as 97.9% within 60 min. The morphology and structure of titanium dioxide were characterized by SEM, TEM and X-ray diffraction. This revealed that the crystalline phases of the prepared titanium dioxide were anatase and rutile, and rutile titanium dioxide was attached to the surface of anatase titanium dioxide. Compared with TiO2 without a wood template, TiO2 prepared with a wood template showed an obvious absorption redshift in the visible light region, which significantly increased absorption. The binding energy of Ti ions in TiO2 with a wood template changed, and Ti3+ ions were produced. Due to the existence of more oxygen vacancies, the photocatalytic activity of TiO2 made with a wood template improved. The multiscale pore structure of TiO2 inherited from the wood template played a key role in developing the visible-light photocatalyst.

Analysis of Surface Properties of Ag and Ti Ion-Treated Medical Textiles by Metal Vapor Vacuum Arc Ion Implantation

The study focuses on the effects of Ag (silver) and Ti (titanium) ions on textiles by MEVVA (metal vapor vacuum arc) ion implantation. In order to comprehend this, the research was executed in three parts. In the first part, the antibacterial efficiencies of Ag and TiO2 were investigated in detail since the antibacterial capabilities of Ag and TiO2 are well known. A group of polyester- and cotton-based medical textiles were modified by Ag and TiO2 ions, with doses ranging from 5 × 1015 to 5 × 1016 ion/cm2. To determine the adhesion capabilities of the implanted ions on surfaces, after the first round of antibacterial tests, these medical textiles were washed 30 times, and then antibacterial tests were performed for the second time. The results were also compared with nanoparticle-treated medical textiles. In the second part, the corrosion and friction capabilities of Ag and Ti ion-implanted polyester textiles, with a dose of 5 × 1015 ion/cm2, were investigated. Finally, the UV protection capabilities of Ag and Ti ion-implanted polyester textiles, with a dose of 5 × 1015 ion/cm2, were investigated. The experiments showed that even after 30 washes, the TiO2 ion-implanted polyester textile had almost 85% antibacterial efficiency. In addition, Ti ion implantation reduced the friction coefficiency of a polyester textile by almost 50% when compared with an untreated textile. Finally, the Ag-ion-implanted polyester textile provided a UV protection factor of 30, which is classified as very good protection.

Encapsulation of Cu-doped TiO2 nanocomposites with the understanding of weak photocatalytic properties for sunscreen applications

We report the fabrication and characterization of varying concentration (x) of copper (Cu)-doped TiO2 nanocomposites [Cu( x )TiO2(1- x )] exploring the photocatalytic properties for sunscreen applications. The Cu-doped TiO2 nanocomposite [Cu( x )TiO2(1- x )] has been synthesized by the low-temperature lab-scale sol-gel hydrothermal method. The concentration of Cu in TiO2 has been chosen as 1%, 2%, 3%, and 4% by weight. With varying concentrations of [Cu( x )TiO2(1- x )], the structural and morphological properties are obtained using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of optical properties for varying concentrations of Cu2+ ions in TiO2 has been studied using Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy. Further, by exploring the photocatalytic properties of fabricated [Cu( x )TiO2(1- x )] has been utilized for sunscreen applications. The concept of sunscreen application of Cu-doped TiO2 can be viewed from the fact that the bare TiO2 generates free radicals that can raise the risk of harmful effects on the skin. Our aim is to synthesize the nontoxic material which can either stop or slow the process of generation of free radicals under sun exposure. In the sun exposure, the risk of free radicals produces by pristine TiO2 can be reduced by doping of copper with titania. We have been observed that [Cu( x )TiO2(1- x )] with x equaling 4% (rutile phase) displays the most effective UV-blocking property with weak photocatalytic activity and is found to be better for sunscreen application. Therefore, Cu-doped TiO2 nanocomposite maintains all the properties of TiO2 at nanoscale as well as improves the concerning property of the cosmetic industry.

A Facile and Controllable Vapor-Phase Hydrothermal Approach to Anionic S2--doped TiO2 Nanorod Arrays with Enhanced Photoelectrochemical and Photocatalytic Activity.

Anionic S2−-doped TiO2 nanorod arrays (S2−-TiO2) were synthesized by a facile and controllable vapor-phase hydrothermal (VPH) approach based on the sulfur source of H2S gas. After the VPH treatment of TiO2 nanorod arrays (TNA), the isolated O2− species replaces the S2− ion in TiO2 (TiO2−xSx). The structural, morphological, optical, compositional, photocatalytic and photoelectrochemical (PEC) properties of the obtained samples were investigated in detail. It was found that S2−-TiO2 can enhance the separation rate of electron–hole pairs, improve the absorption of visible light, and augment the photocatalytic and photoelectrochemical properties. Anionic S2− doping can significantly adjust the absorption cut-off wavelength (409.5–542.5 nm) and shorten the bandgap (3.05-2.29 eV) of TNA. For the degradation of methylene orange (MO) under mercury lamp light, the 0.24 At%S2−-TiO2 (0.24S2−-TiO2) sample exhibited the best photogradation efficiency of 73% in 180 min compared to bare TiO2 (46%). The 0.24S2−-TiO2 showed the highest photocurrent of 10.6 μA/cm2, which was 1.73 times higher than that of bare TiO2 (6.1μA/cm2). The results confirmed that the visible light absorption, photocurrent and photocatalytic activity optimization of TNA are closely related not only to anionic S2−-doped but also different ratios of anionic S2−-doped. It is noteworthy that the VPH approach is very promising for applications in low cost and highly efficient ion doping into nanomaterials for energy devices.

Role of Cr doping in tuning the optical and dielectric properties of TiO2 nanostructures

A series of chromium doped titania samples having compound formula Ti1-xCrxO2 (0≤ x ≤ 0.2) were synthesized through cost-effective acid modified sol-gel process. These samples are characterized through several analytical techniques to explore their microstructural phase, optical and dielectric properties. Rietveld refined x-ray diffraction (XRD) patterns confirm the monophase nature with tetragonal crystal structure in anatase phase having I41/amd space group. The average crystallite size as estimated by the Scherrer's equation varies in the range of ~9–14 nm on doping of Cr ions in TiO2. Structural parameters such as lattice constants, bond length (Ti–O), bond angle <Ti–O–Ti> and x-ray density are found to change as a function of Cr doping. The infrared spectroscopy ensures bending/stretching vibrational modes associated with the functional groups at different wavenumbers. Energy bandgap (Eg) as determined using Tauc's relation varies from 3.10 to 3.75 eV with Cr ions substitution in TiO2 matrix that can be ascribed to the creation of oxygen vacancies/defects in the host lattice. However, a fall in the intensity of photoluminescence as observed on doping of Cr ions is associated with the alteration in oxygen vacancies which are directly responsible for the electron-hole recombination rate. The values of Eg indicate inverse dependence with the Urbach energy (Eu) with the increase in dopant ions. The dielectric measurements as a function of frequency exhibit enhancement in the real and imaginary parts of dielectric constant for the same compositions. A deviation from the universal dielectric response (UDR) mechanism is observed at the lower frequencies for all the samples. Additionally, Cole-Cole plots divulge the non-Debye type of relaxation mechanism and ac conductivity follows the Jonscher power law.

B/Co/Fe tridoped TiO2/SiO2 composite films for improved photocatalytic degradation of organic pollutants under visible light

In order to effectively overcome the inherent defects of TiO2 in practical applications including low quantum efficiency and wide band gap, the B/Co/Fe tridoped TiO2/SiO2 composite films with high photocatalytic properties were prepared by the sol-gel method. The physicochemical properties of catalysts were characterized by XRD, FE-SEM, EDS, DTA-TG, BET, DRS and PL. The results shown that the compositing of SiO2 and doping of B/Co/Fe ions in TiO2 could effectively inhibit the phase transformation of anatase to rutile and the growing of crystal grains at high annealing temperatures. The compositing of SiO2 could enhance the specific surface area (82.6 increased to 335.8 m2/g) of samples and provide more adsorption sites. The doping of B/Co/Fe tridoping could form impurity levels in the band gap of TiO2 to shorten the band gap energy (2.54 ev). And the B/Co/Fe tridoped TiO2/SiO2 films could increase the interfacial transfer rate and decrease recombination rate of electrons and holes. The photocatalytic activities of the B/Co/Fe tridoped TiO2/SiO2 films were evaluated under UV or visible light irradiation with two pollutants as target for photodegradation. The results indicated that the films exhibited more excellent photocatalytic activities compared to pure TiO2. The plausible photocatalytic degradation mechanism had been proposed.

Photocatalytic Degradation of Allura Red by Mn-Ni co-doped Nanotitania under Visible Light Irradiation

Photocatalyst has been extensive interest because of it’s new innovation to the reduce the contamination in the environment. A straight forward and economical procedure has been employed by sol-gel technique for the co-doping of Mn2+ and Ni2+ into TiO2. The co-doped and undoped photocatalysts were described by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray Spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), UV-Visible Diffused Reflectance Spectroscopy (UV Vis-DRS), Transmission electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET). The portrayal results shows that anatase and rutile mixed phase was observed for some co-doped nanocatalysts and the remaining catalysts exhibits anatase phase only. It was observed by FT-IR that the shifting of frequency of Ti-O-Ti in the catalysts was seen due to substitutional doping of Mn and Ni by replace Ti and O, further the photocatalysts shows rough morphology, irregular shape of particle with size (6.5nm) and having high surface area (135.70 m2/g), less band energy (2.7 eV). The photocatalytic action of these materials was assessed by the degradation of Allura red (AR) as a contaminant. The results shows that AR has degraded within 60 minutes at doping concentrations 0.25 Wt% of Mn2+ion and 1.0 Wt% of Ni2+ ion in TiO2 (NMT2) at an optimum reaction parameters pH-4, catalyst dose 0.070g/L and at AR initial dye concentration 0.010g/L.

Role of Ni2+ ions in TiO2 and Pt/TiO2 photocatalysis for phenol degradation in aqueous suspensions

Anatase TiO2 is the most studied environmental photocatalyst, but its efficiency is still not high enough to enable application. Herein we report a positive effect of Ni2+ ions on the photocatalytic reaction in neutral aqueous solution. On addition of 1 mM Ni(ClO4)2, the rates of phenol oxidation on TiO2 and 0.5 wt.% Pt/TiO2 increased by factors of 2.1 and 8.0, respectively. Meanwhile, the formation of organic intermediate was reduced, and the removal of total organic content was enhanced. Interestingly, Ni2+ concentration did not change with irradiation time. Moreover, a maximum rate of phenol degradation was observed with Ni2+ ions, occupying half the surface of TiO2 or Pt/TiO2, where Ni(OH)+ was more active than Ni(OH)2. X-ray photoelectron spectroscopy identified a Ni3+ species produced in absence of phenol. A (photo)electrochemical study revealed that Ni2+ oxidation was favored over H2O oxidation, whereas Ni2+ and Pt inhibited and facilitated O2 reduction, respectively. It is proposed that the adsorbed Ni(OH)+ on TiO2 is oxidized to Ni3+ by the photogenerated holes of TiO2, followed by regeneration through phenol oxidation. The Ni2+-catalyzed organic oxidation then promotes the Pt-catalyzed O2 reduction, and vice visa, resulting into the greatly improved efficiency of charge separation. This work highlights the possibility of Ni2+ ions as the hole mediator of organic oxidation over a semiconductor.

Essential role of treatment in hydrogen atmosphere on creation of ferromagnetic order in carbon incorporated TiO2 nanocomposite

Carbon incorporated TiO2 nanocomposite powders were synthesized by a facile thermal co-decomposition of a mixture of titanium tetrachloride (TiCl4) and sucrose (C12H22O11) as a source of carbon ions. The crystalline structures were studied by x-ray diffraction (XRD) method through the Rietveld refinement technique of analysis. It was found that the samples consist of anatase (A) and rutile (R) with a small amount of brookite (B). It was noticed that the incorporation of C ions in TiO2 lattice enhanced the A to R transformation through creation of oxygen (O)-vacancies. It was concluded that the incorporated small-size C ion-species might occupy interstitial positions in the lattice of host TiO2. Such incorporation should create O-vacancies due to the re-distribution of static charges of ions. The optical properties were investigated by the diffuse reflection spectroscopy (DRS) method. The C-ions incorporation red-shifted the optical band gap, while the hydrogenation of the samples blue-shifted the band gap according to Moss-Burstein effect. Annealing the samples in H2-atmosphere could create O-vacancies, increase carrier concentration, and toss the incorporated in the interstitial C ion-species to occupy the O-vacancies (CO). The possible creation of FM behavior due to CO ions mutual interaction depends on their average separation (RC–C) that was estimated to explain the obtained ferromagnetic (FM) results. The FM properties were observed only with hydrogenated samples that incorporated by ∼1% C. The effective magnetic moment was evaluated to be 1.24 μB/C, which was attributed to the magnetic moment of C2p in addition to some contributions to O-vacancies. This study showed the critical importance of hydrogenation processes to create FM properties in C-incorporated TiO2 nanocomposites.

Understanding Sodium Ion Storage and Diffusivity into CNT-TiO2 Hybrid Electrodes

Sodium ion batteries (NIBs) have attracted much attention of researchers worldwide due to its competence to be used in stationary applications, where cost plays a major role than the size and weight of the battery. Till date, a large variety of materials have been investigated as anodes for sodium ion battery.1 Graphite, the state-of-art of the lithium ion battery anode, can host a negligible amount of sodium during electrochemical intercalation/deintercalation processes.2 Considerable efforts have been made to develop alternative anodes for NIBs such as tin and antimony based alloys3, metal phosphides/oxides/sulphides4, spinel oxides5, and hard carbons6. Hard carbons show a promising sodium ion storage capacity of about 200-400 mAh g-1, but low operating potential of the hard carbon may rise to severe safety issues of dendrite formation and metal plating. Alloy based anodes have very high theoretical capacity between 600 (Na3Sb) to 2600 mAhg-1 (Na3P). Unfortunately, very poor electrochemical performance has been observed for alloy based anodes because of volume changes during sodiation/desodiation which leads to pulverisation. Consequently, an appropriate anode material for NIB is desired which is free from both metal plating and pulverisation. Titanium dioxide (TiO2)7, which is extensively used as multifunctional material because of its stability, non-toxicity, robustness and physio-chemical properties with the advantage of its moderate cost have also been investigated as anodes for NIBs. Titanium based compounds are very stable and safe, delivers long cycle life of over 1000s of cycles. The 3-dimensional open structure of anatase TiO2 offers possible pathways for Na ion insertion and deinsertion. TiO2 offer capacities close to 335 mAh g-1 due to redox reaction of Ti4+/Ti3+. But, electrochemical performance in terms of capacity and rate capability of TiO2 is limited due to its poor conductivity. Therefore, most of the research in this material is focussed on to improve sluggish kinetics of Na+ ion in TiO2 to gain high capacity and good C rate performance. To improve the charge storage and kinetics of TiO2 anodes for NIBs, in this work we present a hybrid material of TiO2 nanoparticles (NPs) is incorporated onto multiwall carbon nanotube (CNTs) (Figure 1a). The cycling stability and C-rate performance of CNT-TiO2 hybrid as anodes for NIBs demonstrate two and half times enhancement in electrochemical performance in the presence of CNT. CNT - TiO2 hybrid shows discharge capacity of about 100 mAh g-1 at current density of 1 A g-1 and cycles for 1000 cycles with little loss in capacity. The overall charge storage properties of pristine TiO2 and CNT-TiO2 hybrid is quantified into pseudo capacitive and diffusion-control Na+ intercalation (Figure 1b). Two times increase in Na+ diffusivity in CNT-TiO2 hybrid is achieved in relation to pristine TiO2. Sodium ion full cell based on CNT-TiO2 hybrid and phosphate based cathode delivers capacity of 184 mAh g-1 and cycles very well. The outstanding electrochemical performance is due to the synergetic effect of TiO2 nanoparticles and conducting CNT network which provides efficient charge storage as well Na+ diffusivity. This work not only develops the fundamental understanding of Na+ storage and kinetics of TiO2 electrode but also its practical realisation in sodium ion full cells. Acknowledgements SG acknowledges MHRD, VKK acknowledges UGC-NET, Govt. of India, and SKM acknowledges Research Center Imarat (DRDO), Hyderabad under grant no. RCI/CAAT/8151/CARS-358 for the financial support. References N. Yabuuchi, K. Kubota, M. Dahbi, and S. Komaba, Chem. Rev., 114, 11636 (2014).B. Jache, and P. Adelhelm, Angew. Chem. Int. Ed., 53, 10169 (2014).D. Ellis, T. D. Hatchard, and M. N. Obrovac, J. Electrochem. Soc., 159 , A1801 (2012).Z.-J. Zhang, Y.-X. Wang, S.-L. Chou, H.-J. Li, H.-K. Liu, and J.-Z. Wang, J. Power Sources, 280, 107 (2015).R. Alcántara, M. Jaraba, P. Lavela, and J. L. Tirado, Chem. Mater., 14, 2847 (2002).E. Irisarri, A. Ponrouch, and M. R. Palacina, J. Electrochem. Soc., 162, A2476 (2015).S. Guo, J. Yi, Y. Sun, and H. Zhou, Energy Environ. Sci., 9 , 2978 (2016). Figure 1

Photocatalytic oxidation of thiophene over cerium doped TiO2 thin film

Samples of TiO2 and TiO2 doped with 2% and 8% cerium ions were prepared by a sol-gel method and used as photocatalysts for the oxidation of vaporized thiophene. X-ray diffraction patterns showed a mixed phase of anatase and rutile for TiO2, while 2%Ce/TiO2 and 8%Ce/TiO2 were dominated by the anatase phase. As seen in the transmission electron microscopy image, the particle size of Ce/TiO2 was about 10 nm which was smaller than the undoped TiO2. The extended x-rays absorption fine structures revealed the substitutional effect of cerium in the TiO2 structure. Cerium-doped TiO2 exhibited a smaller photocurrent compared to that of TiO2, which suggested the electrons were trapped by cerium ions. In situ diffuse reflectance infrared spectroscopy under UV irradiation and x-ray photoemission spectroscopy were used to investigate the photocatalytic oxidation of thiophene on the prepared catalysts. Doping of cerium ions in TiO2 resulted in an enhanced adsorption of thiophene on the catalyst surface. The oxidation products of carboxylic acid with small amounts of sulfate ions were observed. As seen from the infrared absorption spectrum, 2%Ce/TiO2 and 8%Ce/TiO2 exhibited higher photocatalytic activity than those of the undoped TiO2.

Mesoporous Ga-TiO₂: Role of Oxygen Vacancies for the Photocatalytic Degradation Under Visible Light.

Gallium doped mesoporous TiO2 with different weight percentages were synthesized by sol-gel method using Pluronic P123 as the structure directing template. The physico-chemical properties of all the synthesized catalysts were determined by XRD, TEM, SEM-EDAX, N2 adsorption-desorption studies, XPS, UV-vis DRS, FT-IR and photoluminescence spectroscopy. 1.0 wt% Ga-TiO2 exhibited the highest photocatalytic efficiency among all the synthesized materials under visible light due to the high surface area, reduced band gap and suppressed electron-hole recombination. Ga3+ ions substitutions for Ti4+ ions in TiO2 lattice created oxygen vacancies in TiO2 lattice, which created a defect energy level below the conduction band of TiO2 and hence the band gap was reduced. The oxygen vacancy defects was playing significant role to improve the adsorption of oxygen molecules, hydroxide ions and cationic rhodamine B (RhB) on TiO2 surface in an aqueous medium. The lifetime of the charge carriers was also enhanced by trapping the photogenerated electrons in oxygen vacancies and transferring them to the adsorbed O2 to produce superoxide anion radicals (O-. 2 ). The photo-induced holes at valence band reduced the adsorbed OH- ions and produced a large number of .OH radicals, which subsequently degraded the RhB. Hence oxygen vacancies created by gallium doping on TiO2 enhanced the photocatalytic efficiency for the degradation of RhB under visible light.

Effect of TiO2 Nanofiller on Electrical Conductivity of ABS/TiO2 Polymer Nanocomposites: A Free Volume Study

Acrylonitrile Butadiene Styrene (ABS) / Titanium dioxide (TiO2) Polymer nanocomposites with different TiO2 wt % were prepared by solution casting method. Microstructural characterization of ABS/TiO2 polymer nanocomposites was performed by Positron Lifetime Spectroscopy. The increased positron lifetime parameters viz., o-Ps lifetime (τ3) and free volume size (Vf) from 0.2 to 1.0 wt% of TiO2 loading suggests the formation of interfaces due to the increased agglomeration of TiO2 nanoparticles. The increase of two orders of magnitude change in electrical conductivity (σ) of ABS/TiO2 polymer nanocomposites with the increasing free volume hole size (Vf) as a function of TiO2 nanoparticles loading . The increased electrical conductivity (σ) with the increased free volume hole sizes (Vf) indicates the increased interfacial space for the movements of charge carriers and TiO2 ions. Miyamoto and Shibayma model for ion conduction has been used to explore the effect of free volume hole size (Vf) on the electrical conductivity (σ) in ABS/TiO2 polymer nanocomposites. Fourier Transform Infrared Spectroscopy (FTIR) suggests the improved chemical and physical interaction between the functional groups of TiO2 and ABS polymer side chain

Synergetic effect of N3−, In3+ and Sn4+ ions in TiO2 towards efficient visible photocatalysis

Nitrogen, indium and tin doped TiO2 photocatalyst (TiO2-N-In-Sn) was prepared by sol–gel method. It is revealed that Sn ions were doped into TiO2 lattice in substitutional mode, forming a new doped energy level 0.2 eV below the conduction band of TiO2; nitrogen and indium ions are presented as surface NOx and O-In-Clx, located at 0.3 eV above the valence band and 0.3 eV below the conduction band, respectively. Owing to the synergetic effect of introduced nitrogen, indium and tin, the band structure of TiO2 is adjusted to extend the visible absorption and promote the separation of charge carriers, resulting in an improved photocatalytic activity on photo-degradation of 4-CP under visible irradiation.

Anatase TiO2 as an Anode Material for Rechargeable Aqueous Aluminum-Ion Batteries: Remarkable Graphene Induced Aluminum Ion Storage Phenomenon

The electrochemical intercalation and extraction of Al3+ ion in anatase TiO2 is illustrated in various aqueous electrolytes in an attempt to demonstrate the viability of TiO2 as an anode material for rechargeable aqueous aluminum-ion batteries. It is well understood that the primary barrier for diffusion of Al3+ ion in TiO2 is the poor electronic conductivity of TiO2. It is revealed that a small fraction of graphene (<2 wt %) could induce ultrafast diffusion of Al3+ ion in TiO2. Estimation shows that graphene remarkably enhances the Al3+ ion diffusion coefficient in TiO2 by 672 times. Discharge capacities in the range of 33–50 mAhg–1 are obtained at a high current rate of 6.25Ag–1for graphene incorporated TiO2. It is also seen that the nature of electrolytes critically influences the Al3+ ion insertion phenomenon. The possibility of reversible crystal phase transition of TiO2 to aluminium titanate due to Al3+ ion intercalation-extraction is also demonstrated for the first time.

Nanofiber-based brush-distributed sensor for detecting heavy metal ions

A brush-distributed metal oxidation sensing nanostructure is developed by growing zinc oxide (ZnO) nanorods on electrospun titanium dioxide (TiO2) nanofibers to improve ions adsorption of lead and copper. A pair of inductive plane coils are designed to measure inductive variation induced by the adsorbed ion concentration. The brush-distributed ZnO–TiO2 nanofibers are fabricated by using electrospinning and hydrothermal methods that are deposited on the PVDF-formed nanofiber membrane to enhance copper and lead ions adsorption efficiency. The sensitivity has been promoted based on the van der Waals force and produced hydroxyl from grown surface nanorods. The TiO2 structure was examined by checking XRD patterns. These diffraction peaks are indexed as the (101), (004), (200), and (105) of anatase TiO2 and are consistent with the standard data (JCPDS No. 78-2486). The circular coils are designed and simulated using the finite element method to sense metal ions by measuring concentration-dependent magnetic flux variation. The developed ZnO–TiO2 ion sensing composites include the following advantages: simple fabrication process, low cost, high selectivity, highly effective adsorption, specific surface area and porosity, rapid response, and good repeatability and reproducibility.

Optimization of cerium doping of TiO2 for photocatalytic reduction of CO2 and photocatalytic decomposition of N2O

The cerium-doped TiO2 photocatalysts (0–0.8 mol% Ce) were prepared by using a sol–gel method. Textural, structural, optical and electronic properties of Ce/TiO2 photocatalysts were characterized in detail by using nitrogen physisorption, powder X-ray diffraction, diffuse reflectance UV–Vis spectroscopy and contact potential difference measurements. It was proved that increasing amount of cerium ions in TiO2 (1) decreased the anatase crystallite size, which corresponded to the increase in specific surface area of the photocatalysts, and (2) decreased the absorption edge (shifting the spectral response toward the visible light region). The prepared photocatalysts were tested for CO2 photocatalytic reduction in a stirred batch annular reactor, and methane was a main product. The photocatalytic decomposition of nitrous oxide was carried out in batch reactor with circulation, and only oxygen and nitrogen were detected as reaction products. It was found out that the energies of electrons and holes played the key role in both photocatalytic reactions and can be markedly affected by doping of TiO2 by cerium.

The influence of pH values on the existing states of In and B ions in TiO2

A series of In and B co-doped TiO2 samples are prepared by sol–gel method under different pH values. The detailed existing states of introduced In and B ions are investigated via XRD, FT-IR, XPS and HRTEM. It is found that the B ions are mainly doped into TiO2 in interstitial mode and In ions exist as surface O-In-Clx species when the pH values are in the range of 0.31∼0.65. With the increase of the pH values (0.82∼3.40), the introduced In and B ions would react with each other to form InBO3. The existing states of In and B ions in TiO2 can be easily changed by adjusting the pH values to achieve a new type of TiO2 based materials with controlled structures.