Pure Anatase Research Articles

3D TiO2 nanotube arrays with anatase-rutile phase junction and oxygen vacancies for promoted photoelectrochemical water splitting

Constructing TiO2 phase junction with visible light response, effective separation and transfer of photogenerated charges is desperately needed for photoelectrochemical water splitting. Herein, 3D-TiO2 nanotubes arrays-based phase junction consisted of anatase core and rutile shell as well as oxygen vacancies are successfully fabricated via a new one-step annealing method in Ar atmosphere. The synergistic effect of phase junction and oxygen vacancies not only boosts the separation of photogenerated charges, but also enhances the utilization efficiency of the incident, reflected and/or refracted visible light captured by the 3D configuration. Moreover, the oxygen vacancies can act as electron donors, which could effectively improve the electrical conductivity, and hence further accelerate the separation and transfer of photogenerated charges. Benefiting from these advantages, the optimized 3D-TiO2 NTAs-based phase junction display a maximal photocurrent density of 1.5 mA cm−2 at 0.22 V vs. Ag/AgCl with Faradic efficiency of 100%, which is approximately 1.9 folds higher than that of pure anatase 3D-TiO2 NTAs. The technique and strategy could also be extended to other application of TiO2 NTAs such as solar cells and photocatalysis.

Non-enzymatic amperometric glucose sensing on CuO/mesoporous TiO2 modified glassy carbon electrode.

The present study illustrates the fabrication of a glucose sensing electrode based upon binary composite of copper oxide and mesoporous titanium dioxide on glassy carbon (CuO/TiO2/GCE). The X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis evidently showed the phase pure monoclinic CuO nanoparticles and anatase TiO2. N2 adsorption-desorption analysis verified the mesoporosity in TiO2 with specific surface area greater than 105 m2 g-1. Electrochemical impedance spectroscopic analysis proved the remarkable decrease in the charge transfer resistance and facilitation of electron transfer process on the fabricated electrode. The optimum weight ratio of CuO to TiO2 was 1 : 1, and the optimum potential was 0.6 V vs. saturated calomel electrode. The chronoamperometric measurements displayed a detection limit of 1.9 μM, and sensitivities of 186.67 μA mM-1 cm-2 and 90.53 μA mM-1 cm-2 in two linear ranges of 0.05 to 5.2 mM and 5.2 to 20 mM, respectively. The amperometric analysis further showed good reproducibility, high specificity and outstanding stability of the modified electrode.

The Influence of Synthesized TiO2-Nanoparticles on the Performance of Inks Utilized in Printing Documents

Titanium dioxide is also called titania and occurs in nature in anatase and rutile forms. It is widely used as a white pigment, catalyst support, and photocatalyst. Nano-TiO2 pigments in pure crystallographic anatase phases have been successfully synthesized via sol-gel method. Nano-TiO2 material has been characterized by various techniques such as XRD, TEM, and XPS. The prepared nano-TiO2 was mixed with two different offset inks (falcon and jobbing) to upgrade the physical and optical properties of the offset inks and compared with Degussa TiO2 before and after the application was tracking and measured. Generally, requiring a small amount of modification is better to avoid any ink malfunction, nano ink requires 0.1 % is because of the photoactive anatase structure of TiO2, while Degussa requires 1 % because it has a 15% rutile structure, which considered a photoinactive phase structure of TiO2.

First-principles assessments of the electronic, and magneto-optical characteristics of Fe–Mn co-doped anatase TiO2 for photo-catalysis applications

First principles modeling is conducted to scrutinize the structural, chemical, electronic structures, bonding character, and magneto-optical features of intrinsic or pure anatase TiO2, Fe or Mn single-atom doped, and Mn–Fe diatom co-doped anatase TiO2 systems, respectively. Herein, the spin-polarized density functional theory (DFT) concerted with the on-site Hubbard (U) correction scheme for the Coulomb interaction, is utilized for the exchange-correlation term, as the generalized gradient approximation (GGA)+U. The spin-polarized density of states of Mn mono-atom doped anatase TiO2 material indicated a magnetic semiconductor attribute for both down/up spin components. Conversely, the outcome spin-polarized density of states of both Fe-doped and Mn–Fe co-doped anatase TiO2 materials illustrated the emergence of an intermediate band behavior. Accordingly, three magnetic impurity bands are produced in Mn–Fe co-doped anatase TiO2, the first two spin-up bands are located just uppermost the valence states nearby the Fermi level and the third spin-up/down band is lying far from the Fermi level just below the minimum conduction band. Interestingly, the spin-polarized charge density displayed an orbital ordering between the O 2p-orbitals and 3d-orbitals of Mn–Fe doped diatoms in the host TiO2 anatase system. The valuable optical ingredients, such as the optical absorption coefficient, refractive index, reflectivity spectra, optical conductivity, and electron energy loss function, are inspected and discussed. Moreover, the optical absorption coefficient characteristics of the mono-doped Mn/Fe and Mn–Fe co-doped TiO2 anatase structure displayed a relocation in the absorption feature edges towards the visible electromagnetic radiation regime. This means that the induced impurity bands delineate the essential contributor for boosting the catalytic activity in the visible light. It is expected that the Fe–Mn co-doped anatase TiO2 system could be a compelling candidate for its ultimate use in the photo-catalysts or magnetic storage devices.

High anisotropic magnetoresistance, perfect spin-filtering effect, and negative differential resistance effect of Cr-doped anatase phase TiO2

Anisotropy-based half-metallic materials are highly efficient in spintronic devices and have important applications in spintronics. Anatase phase TiO2 has attracted much attention because of its anisotropy, but its non-magnetism limits its applications in spintronics. We investigate the electronic structure of 3d transition metal-doped anatase phase TiO2 by first principles method to achieve spin injection of anatase. The calculation results exhibit that the Sc, Cr, Mn, Fe, and Ni-doped systems are half-metallic ferromagnets while other doped systems behave as magnetic metals except the V-doped system is a magnetic semiconductor. The calculated formation energy under O-rich condition are negative shows that all half-metals are thermodynamically stable, and we construct devices along the y-direction of the half-metal and find that the device based on the Cr-doped system has the best electronic transfer capacity under zero bias. Then we use the Cr-doped system as the electrode and the pure anatase unit cell as the central scattering region to construct devices in different directions. We find that the magnitude of the current along different transport directions varied greatly, and the calculated anisotropic magnetoresistance was as high as 300%. Furthermore, whether spin configurations (PC) or antiparallel configurations (APC), there is a 100% spin-filtering efficiency of the device, and we find a significant negative differential resistance effect of the device in PC. These results suggest that Cr-doped anatase phase TiO2 can be used in spintronics.

Deep-learning framework for fully-automated recognition of TiO2 polymorphs based on Raman spectroscopy

Emerging machine learning techniques can be applied to Raman spectroscopy measurements for the identification of minerals. In this project, we describe a deep learning-based solution for automatic identification of complex polymorph structures from their Raman signatures. We propose a new framework using Convolutional Neural Networks and Long Short-Term Memory networks for compound identification. We train and evaluate our model using the publicly-available RRUFF spectral database. For model validation purposes, we synthesized and identified different TiO2 polymorphs to evaluate the performance and accuracy of the proposed framework. TiO2 is a ubiquitous material playing a crucial role in many industrial applications. Its unique properties are currently used advantageously in several research and industrial fields including energy storage, surface modifications, optical elements, electrical insulation to microelectronic devices such as logic gates and memristors. The results show that our model correctly identifies pure Anatase and Rutile with a high degree of confidence. Moreover, it can also identify defect-rich Anatase and modified Rutile based on their modified Raman Spectra. The model can also correctly identify the key component, Anatase, from the P25 Degussa TiO2. Based on the initial results, we firmly believe that implementing this model for automatically detecting complex polymorph structures will significantly increase the throughput, while dramatically reducing costs.

TiO2 Nanowires on TiO2 Nanotubes Arrays (TNWs/TNAs) Decorated with Au Nanoparticles and Au Nanorods for Efficient Photoelectrochemical Water Splitting and Photocatalytic Degradation of Methylene Blue

In this study, TiO2 nanowires on TiO2 nanotubes arrays (TNWs/TNAs) and Au-decorated TNWs/TNAs nanostructures are designed and fabricated as a new type of photoanode for photoelectrochemical (PEC) water splitting. The TNWs/TNAs were fabricated on Ti folds by anodization using an aqueous NH4F/ethylene glycol solution, while Au nanoparticles (NPs) and Au nanorods (NRs) were synthesized by Turkevich methods. We studied the crystal structure, morphology, and PEC activity of four types of nanomaterial photoanodes, including TNWs/TNAs, Au NPs- TNWs/TNAs, Au NRs-TNWs/TNAs, and Au NPs-NRs-TNWs/TNAs. The TiO2 and Au-TiO2 samples exhibited pure anatase phase of TiO2 with (0 0 4), (1 0 1), and (1 0 5) preferred orientations, while Au-TiO2 presented a tiny XRD peak of Au (111) due to a small Au decorated content of 0.7 ± 0.2 at.%. In addition, the samples obtained a well-defined and uniformed structure of TNAs/TNWs; Au NPs (size of 19.0 ± 1.9 nm) and Au NRs (width of 14.8 ± 1.3 nm and length of 99.8 ± 15.1 nm) were primarily deposited on TNWs top layer; sharp Au/TiO2 interfaces were observed from HRTEM images. The photocurrent density (J) of the photoanode nanomaterials was in the range of 0.24–0.4 mA/cm2. Specifically, Au NPs-NRs- decorated TNWs/TNAs attained the highest J value of 0.4 mA/cm2 because the decoration of Au NPs and Au NRs mixture onto TNWs/TNAs improved the light harvesting capability and the light absorption in the visible-infrared region, enhanced photogenerated carriers’ density, and increased electrons’ injection efficiency via the localized surface plasmon resonance (LSPR) effect occurring at the Au nanostructures. Furthermore, amongst the investigated nanophotocatalysts, the Au NPs-NRs TNWs/TNAs exhibited the highest photocatalytic activity in the degradation of methylene blue with a high reaction rate constant of 0.7 ± 0.07 h−1, which was 2.5 times higher than that of the pristine TNWs/TNAs.

Green synthesized TiO2 nanoparticles: Structural characterization and photoinduced antifungal activity against P. steckii

This study synthesized titanium dioxide (TiO2 ) nanoparticles (NPs) from mango leaf extract and investigated the features and antibacterial capabilities of three different. The microscopic morphological observation, scanning electron microscopy, and transmission electron microscopy results showed that all three NPs showed agglomeration phenomenon, and the TN-1 sample existed as large agglomerates, whereas the agglomeration phenomenon of TN-3 sample was improved by the modified, without large agglomerates. The biosynthetic TN-2 and TN-3 NPs were spherical and uniform in size, whereas those of the TN-3 sample was the smallest, ranging from 10 to 30nm. X-ray diffraction and Raman spectroscopy results exhibited that these were highly pure anatase NPs. The result of ultraviolet (UV)-visible-near-infrared spectral analysis showed that the TN-2 and TN-3 samples displayed higher UV absorption properties than the TN-1 samples and were highest in the modified NPs, which was more suitable for preparing chitosan-based nanocomposite material in future experiments and studies. The colony diameters of the TN-1, TN-2, and TN-3 treatment groups were 7.99, 7.80, and 6.86mm, respectively, after 120min of UV light induction at a wavelength of 365nm. Significant differences were evident between the TN-3 and the other two groups (p<0.05), indicating that the TN-3 sample more effectively inhibited Penicillium steckii than the other TiO2 NPs. PRACTICAL APPLICATION: Nanomaterials coated film preservation is widely used in fruit and vegetable preservation. In this paper, TiO2 nanomaterials will be green synthesized using mango leaf and structurally characterized, whereas antibacterial tests will be conducted against the mango fruit-specific bacterium Penicillium steckii, which will provide a theoretical basis for the storage and preservation of mango.

Facile synthesis of N-doped biphasic TiO2 nanoparticles with enhanced visible light-driven photocatalytic performance

Undoped and N-doped TiO2 anatase/brookite mixed-phase nanoparticles were synthesized via a facile sol-gel method using urea as a nitrogen source. Surprisingly, nitrogen played a dual role in doping and controlling the anatase and brookite phases in the nanoparticles. The as-synthesized photocatalysts were characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis and UV–vis diffuse reflectance spectroscopy (DRS). PXRD results revealed that TiO2 nanoparticles consisted of a mixture of anatase and brookite crystalline phases where the anatase phase increased with increasing urea concentration (1–60 wt. %), and the pure anatase phase was found at a urea concentration of ≥15 wt. %. N-doped anatase/brookite mixed-phase (brookite ̴ 20 wt. %) nanoparticles exhibited superior photocatalytic activity over others in degrading rhodamine-B (RhB) under simulated visible light irradiation, and its photocatalytic performance was comparable to that of Degussa P25. The enhanced photodegradation activity was credited to biphasic composition, narrower bandgap energy, and stronger light absorption in the visible region.

High relative permittivity and excellent dye photo-elimination: Pure and (Zr4+, Y3+, Sb5+) multi-doped anatase TiO2 structure

Herein, multifunctional characteristics including solar photocatalytic, dielectric constant and ac electrical conductivity have been studied for pure and Zr4+, Y3+ and Sb5+ multidoped TiO2 n-type semiconductor. Pure, Zr doped, (Zr, Y) codoped and (Zr, Y, Sb) tridoped TiO2 with chemical compositions of TiO2, Ti0.98Zr0.02O2, Ti0.96Zr0.02Y0.02O2 and Ti0.94Zr0.02Y0.02Sb0.02O2 were prepared via a low cost coprecipitation technique. All compositions reveal a pure single phase of anatase TiO2 structure with different unit cell volume due to the differences in ionic radii between parent cation (Ti4+ = 0.605 Å) and dopants ions (Zr4+ = 0.72 Å), (Y3+ = 0.9 Å) and (Sb5+ = 0.6 Å). Morphological changes for TiO2 particles were seen due to incorporation of Zr4+, Y3+ or Sb5+ cations into TiO2 lattice. Optically, Zr4+, Y3+ and Sb5+ ions cause a red shift for the absorption edge and reduce the width of the bang gap energy of TiO2 as well as enhance its refractive index value. High dielectric constant of 2214 (42 Hz) was detected for Ti0.94Zr0.02Y0.02Sb0.02O2 composition. Ti0.94Zr0.02Y0.02Sb0.02O2 sample reveals the highest ac electrical conductivity (σac) values compared to undoped TiO2, Ti0.98Zr0.02O2 and Ti0.96Zr0.02Y0.02O2 samples. High efficiency (∼100%) and fast (20–40 min) solar photodegradation characteristics for 10 ppm Congo red (CR) was realized via TiO2 and Ti0.96Zr0.02Y0.02O2 catalysts. For 40 ppm CR, pure TiO2 exhibits a high photocatalytic activity of 80% after 120 min of sunlight irradiation. Interestingly, this study also illustrates that the starting materials (titanium butoxide-butanol solvent) used in the synthesis process play a significant role in the phase structure as well as the ultimate photocatalytic properties of TiO2 based compositions.

A New Study on the Effect of Pure Anatase TiO2 Film Thickness on Gentian Violet Photodegradation Under Sunlight: Considering the Effect of Hole Scavengers

In this paper, pure anatase TiO2 thin films were grown on glass substrates by using sol-gel dip-coating method. To study the physical, chemical and optical properties of the deposits, TiO2 thin films were synthesized with thickness (241.5, 258.19, 230.33 and 302.35 nm). XRD patterns show that TiO2 films were grown with unique anatase phase (101). The photocatalytic test shows that film (~ 302 nm) gives high photodegradation of gentian violet (GV) under sunlight irradiation due to the low number of defect sites. The increase in film thickness and the decrease of surface roughness and crystal size decrease the number of defect sites in the material which lead to low recombination rate of charge carriers. The use of Ag+ as hole scavenger increases the photocatalytic activity 4.75 times within the first hour. The photocatalysis process showed that Ag+ can be reduced on the surface of photoactivated TiO2 thin films to obtain sun-photodeposited/dip-coated AgO/TiO2 (p-n) heterojunction. HIGHLIGHTS Pure anatase TiO2 thin films were successfullysynthesized via sol-gel dip-coating method High thickness (302 nm) of TiO2 thin film exhibits high photocatalytic activity for photodegradation of GV under sunlight irradiation The presence of Ag+ in wastewater shows high photocatalytic activity of TiO2 films with 4.75 times within the first hour The possibility of sun-photodeposited/dip-coated of (p-n) AgO/TiO2 heterojunction is discussed GRAPHICAL ABSTRACT

Selective hydroxylation of benzene to phenol via C[sbnd]H activation over mesoporous Fe2O3-TiO2 using H2O2

The omnipresence of CH bonds in organic molecules enamors chemists for the functionalization of CH bonds towards value-added molecular scaffolds. Mesoporous Fe2O3-TiO2 mix-oxide catalyst has been successfully synthesized via a triblock-copolymer (P123) mediated sol-gel method and catalytically tested in selective hydroxylation of benzene. The as-synthesized catalysts were comprehensively characterized by powder XRD, Raman spectroscopy, FT-IR, N2-physisorption, FESEM, HRTEM, XPS, and NH3-TPD techniques. The physicochemical characterizations evidence that Fe(III) ions incorporate into the pure anatase TiO2 lattice framework and the crystallite size decreases as iron concentration increases. The XPS analyses confirm the Fe3+ state (BE 710.3 eV) in Fe-O-Ti with a peak at 712.1 eV for Fe3+ of Fe2O3. The NH3-TPD results show that the 5 wt% Fe-TiO2 has a higher total acidity of 105 µmol/g. Interestingly, a further increase in iron amount decreases the total acidity. Herein, we observe that the surface acidity directs the selectivity towards phenol. The effect of different reaction parameters was carefully investigated. Under the optimized conditions, 5% Fe-TiO2 with notified strong acid sites gives a higher phenol yield of 31.2% with > 99% selectivity; moreover, the catalyst is reusable at least four times.

Porous sulfur-doped titanium dioxide for improving photocatalytic VOC removal and biological disinfection under low intensity fluorescent light

In this research work, we have utilized the probe sonication assisted sol-gel method to prepare highly active porous sulfur doped TiO2 (PST). The cationic sulfur (S6+) doped into the TiO2 lattice created a new intermediate level (S2p) between the valence band (VB) and conduction band (CB). The doping of sulfur on TiO2 led to additional absorption features in the visible region. The spherical-shaped porous PST nanoparticles were confirmed from SEM which influence the active sites for the photocatalytic performance. Instantaneous decomposition of pollutant p-xylene, a carcinogenic volatile organic compound, was accomplished using the stable PST photocatalyst working under low intensity fluorescent visible light. PST characterized by a pure anatase crystal structure, a high specific surface area of 76m2/g (1.52 times greater than commercial P25) and a pore size of 17 nm favored a substantially increased adsorption of VOC molecule on the catalyst surface and enhanced the photocatalytic activity with respect to p-xylene decomposition. Disinfecting effect of PST photocatalyst against E.coli was also investigated. Therefore, the high efficient PST functions as a multipurpose photocatalyst and could be used in air purification treatment due to its high recyclability.

S- and N-Co-Doped TiO2-Coated Al2O3 Hollow Fiber Membrane for Photocatalytic Degradation of Gaseous Ammonia.

This study successfully prepared and tested sulfur- and nitrogen-co-doped TiO2-coated α-Al2O3 (S,N-doped TiO2/Al2O3) hollow fiber (HF) membranes for efficient photocatalytic degradation of gaseous ammonia (NH3). Thiourea was used as a sulfur- and nitrogen-doping source to produce a S,N-doped TiO2 photocatalyst powder. For comparative purposes, undoped TiO2 powder was also synthesized. Through the application of a phase-inversion technique combined with high-temperature sintering, hollow fibers composed of α-Al2O3 were developed. Undoped TiO2 and S,N-doped TiO2 photocatalyst powders were coated on the α-Al2O3 HF surface to obtain undoped TiO2/Al2O3 and S,N-doped TiO2/Al2O3 HF membranes, respectively. All prepared samples were characterized using XRD, TEM, XPS, UV-Vis, SEM, BET, FT-IR, and EDS. S and N dopants were confirmed using XPS and UV-Vis spectra. The crystal phase of the undoped TiO2 and S,N-doped TiO2 photocatalysts was a pure anatase phase. A portable air purifier photocatalytic filter device was developed and tested for the first time to decrease the amount of indoor NH3 pollution under the limits of the lachrymatory threshold. The device, which was made up of 36 S,N-doped TiO2/Al2O3 HF membranes, took only 15-20 min to reduce the level of NH3 in a test chamber from 50 ppm to around 5 ppm, confirming the remarkable performance regarding the photocatalytic degradation of gaseous NH3.

Nanowires-Assembled TiO2 Nanorods Anchored on Multilayer Graphene for High-Performance Anodes of Lithium-Ion Batteries.

Multilayer graphene (MLG) prepared via ultrasonic exfoliation has many advantages such as its low-cost and defect-free nature, high electronic conductivity, and large specific surface area, which make it an apt conductive substrate for TiO2 composites. To synthesize graphene/TiO2 hybrids, traditional methods that greatly depend on the chemical bond of oxygen-containing functional groups on graphene with titanium cations are not applicable due to the absence of these functional groups on MLG. In this work, a facile chemical method is developed to directly deposit TiO2 on the MLG surface without the introduction of chemically active groups. With this method, four types of TiO2 materials, that is pure anatase TiO2 nanoparticles, a mixture of anatase TiO2 nanoparticles and rutile TiO2 nanoflowers, pure rutile TiO2 nanoflowers, and pure rutile TiO2 nanorods, are homogeneously anchored on the MLG surface by controlling the amount of HCl in the reactant. Interestingly, the rutile TiO2 nanorods in the TiO2/MLG composite are assembled by many TiO2 nanowires with an ultra-small diameter and ultra-long length, which provides a better synergetic effect for high performances as LIB anodes than other composites. A specific capacity of 631.4 mAh g−1 after 100 cycles at a current density of 100 mA g−1 is delivered, indicating it to be a valuable LIB anode material with low cost and high electrochemical performances.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Preparation and characterization of TiO2 photocatalytic composites supported by blast furnace slag fibres for wastewater degradation

The carrier selection for photocatalytic materials is critical for photocatalytic degradation technology. In this study, blast furnace slag fibre (BFSF) prepared using metallurgical waste was employed as a carrier for TiO2. The photocatalytic activity of the resulting TiO2/BFSF composite and its influencing factors during the sol-gel process was systematically investigated via TG-DTA, XRD, SEM-EDS, BET, UV–Vis absorption spectroscopy, degradation of methylene blue (MB) experiments, and mass loss technology. The results showed that the crystal phase of TiO2 transformed from pure anatase to a mixture of anatase and rutile and then to pure rutile as the calcination temperature increased from 350 °C to 800 °C. When the number of TiO2 loading cycles increased from 1 to 6, the TiO2 film changed from thin to thick and from uneven to uniform, until cracking and spalling finally occurred. When the number of TiO2 loading cycles and calcination temperatures increased, the photocatalytic activity increased and then decreased. After loading TiO2 sol four times and calcining at 450 °C for 2.5 h, a uniform and dense anatase TiO2 film was observed to be wrapped on the BFSF, achieving the highest photocatalytic activity and a maximum degradation ratio of 95.3%. The TiO2/BFSF composite showed excellent reusability. After four reuse cycles, the degradation ratio remained at 66.2%. Three potential mechanisms were proposed for photocatalytic degradation. The water and alkali resistance of BFSF markedly increased after the TiO2 thin film was loaded. This study therefore provides strategies to improve the photocatalytic activity of TiO2 and expands the high-value-added application of BFSF.

Rhus Semialata Derived Carbon Quantum Dots Decorated Pt Deposited TiO2 for Efficient Light‐Driven Hydrogen Production

AbstractAs a fuel, hydrogen may effectively replace the traditional fossil fuels. TiO2 has been in use the most in semiconductors for photocatalytic hydrogen generation, according to a detailed review of the prior art. In our research, we created a photocatalytic system made of an H‐CD/Pt−TiO2 heterostructure, where carbon dots (H‐CD) were derived from a natural plant source called Rhus Semialata and 1 wt% Pt−TiO2 using photo‐deposition technique. After thorough characterization using various techniques including XPS, XRD, UV‐DRS, etc., the nanocomposites as‐prepared as well as the pristine materials were examined for their hydrogen generation capabilities using a 450 W Xe−Hg lamp. Inference from the experimental data showed that 1 wt %‐ Pt/TiO2 nanocomposite with 1 % H‐CD demonstrated a higher rate of hydrogen production (180.7 mmol h−1 g−1cat) than 1 wt%‐ Pt/TiO2. In this work, H‐CD and Pt play the role of photosensitizer and co‐catalyst respectively in enhancing the hydrogen generation of the nanocomposite compared to that of pure anatase TiO2 under similar conditions.

One‐Step Synthesis of Sulfate‐Modified Titania Nanoparticles with Surface Acidic and Sustained Photocatalytic Properties via Solid‐State Thermolysis of Titanyl Sulfate

AbstractTitania nanoparticles surface‐functionalized with sulfate were prepared by thermal degradation of titanyl sulfate. At 600 °C pure anatase phase is obtained. X‐ray photoelectron spectroscopy (XPS) showed 1.4 at.% sulfur in the +6 oxidation state. At 700 °C anatase was still present, which is attributed to the presence of small amounts of stabilizing sulfate groups only detectable by high‐resolution XPS, segregating to the nanoparticle interfaces. Adsorption and photocatalytic degradation of acetaldehyde reactions were studied by in situ diffuse reflectance Fourier transform spectroscopy and 2D correlation spectroscopy, and compared with pure anatase nanoparticles. Aldol condensation of acetaldehyde and subsequent accumulation of crotonaldehyde was lower on sulfate‐modified titania. Butanoate was identified as an intermediate, which forms after dimerization and aldol condensation. Much more carboxylates and carbonates accumulated on pure anatase catalysts compared with sulfate‐modified anatase during photocatalysis. It is conjectured that surface acidic photocatalysts could be beneficial for achieving sustained activity for photodegradation of organic pollutants.

Evolution of surface properties of titanium oxide thin films

Titanium oxide thin films were deposited by rf magnetron sputtering of Ti metallic target in flow-controlled O2 + Ar atmosphere. Comprehensive investigations of crystallographic structure, phase composition, morphology and optical properties were performed by means of X-ray diffraction, X-ray reflectivity (XRR), scanning electron microscopy, optical spectrophotometry, and X-ray photoemission spectroscopy. It was found that as the O2/(O2 + Ar) flow ratio increased, the microstructure of thin films changed from TiO, Ti2O3, to rutile TiO2, rutile-anatase mixture and, finally, to pure anatase. Special emphasis was given to soft X-ray absorption spectroscopy in surface-sensitive total electron yield mode, which provided simultaneous information on electronic occupancy and local atomic structure. Studies of titanium L23 edge revealed systematic changes in crystal field strength, increasing upon rutile formation and decreasing when anatase became the dominant phase in sputtered films. Diffuse reflectance and XRR were employed to investigate the light scattering effects related to the surface roughness. The highest value (5.3 nm) of XRR roughness was observed for pure rutile sample. Performance of films as photoanodes in photoelectrochemical cells was assessed by photocurrent vs potential and time measurements. Results revealed that crystallized, stoichiometric films containing a mixture of anatase and rutile were promising photoanode materials for green hydrogen generation.