Anatase Phase Of Titania Research Articles

Investigation of Dielectric and Piezoelectric Properties of Polyvinylidene Fluoride Films Reinforced with Anatase Phase Titanium Dioxide for Pressure Sensing

Investigation of Dielectric and Piezoelectric Properties of Polyvinylidene Fluoride Films Reinforced with Anatase Phase Titanium Dioxide for Pressure Sensing

Synergistically Photocatalytic Conversion of Two Greenhouse Gases to Liquid‐Phase Oxygenates under Anaerobic Conditions

Collaborative conversion of methane and carbon dioxide into sustainable chemicals is an appealing solution to simultaneously overcome both environmental problems and energy crisis. However, this reaction is limited to the preparation of syngas with the unfavorable feature for transportation and storage. Herein, liquid formaldehyde as product is fabricated by the collaborative conversion of methane and carbon dioxide using anatase phase titanium dioxide as photocatalyst. The productivity reaches 14.65 mmol g−1 with 88.32% selectivity. In situ diffuse reflectance Fourier transform infrared spectroscopy, isotope testes, and theoretical calculation clarify that the photoexcited holes and electrons engage into methane oxidation and carbon dioxide reduction over anatase using surface hydroxyl species and oxygen vacancy as active sites, respectively. The consumption of surface hydroxyl species on methane oxidation promotes the oxygen vacancy formation for carbon dioxide adsorption, mutually the carbon dioxide provides the oxygen atom for surface hydroxyl species facilitating methane oxidation. The consumption of photoelectrons and photoholes on carbon dioxide reduction and methane oxidation balances the number of photogenerated carriers and ensures the catalytic system stability. In this work, the avenue is broadened toward the co‐conversion of greenhouse gas into desirable chemical products in a sustainable way.

DFT Studies on Cun/TiO2 (n=1-7) System for Water Splitting

Copper deposited on titania is active in numerous catalytic reactions, incl. water splitting [1]. The activity of the system depends on the size of the copper phase, whether it is present as single atoms, sub-nanometer clusters, or nanoparticles.The aim of the current contribution is to elucidate the relationship between the size of the copper active phase and its electronic and geometric properties by performing Density Functional Theory (DFT) calculations with PBE functional and the def2-TZVP basis set.Theoretical model of the system comprised of a cluster model of anatase phase of titania – (TiO2)34 - with clusters of copper of varying sizes on top of it. The ground-state geometric and electronic structures were elucidated. Next, their redox and photochemical properties were determined: frontier (HOMO, LUMO) orbitals were defined, energy gaps, total and partial density of states were plotted and analysed. The interactions between components of the systems, in particular the influence of the support on the copper electronic structure, were investigated. Next, the reactivity of the metal phase towards typical intermediates observed during water splitting (H2O, OH, O, and H) was studied.The performed calculations demonstrated that the presence of metal determines the energetics and character of the frontier orbitals of the catalyst. The size of copper active phase influences the bond lengths and bond orders with studied reagents.Acknowledgements: This work was supported by the National Science Centre, Poland within Solar-Driven Chemistry project no 2019/01/Y/ST4/00024. This publication is based upon work from COST Action CA 18234 “Computational materials sciences for efficient water splitting with nanocrystals from abundant elements”, supported by COST (European Cooperation in Science and Technology). We gratefully acknowledge Polish high-performance computing infrastructure PLGrid (HPC Centers: ACK Cyfronet AGH) for providing computer facilities and support within computational grant no. PLG/2020/013927.Literature:[1] Cheng Cheng, Wei-Hai Fang, Run Long, and Oleg V. Prezhdo, JACS Au 2021, 1, 5, 550–559

Morphology matters: Investigating the influence of granules and nanofibers on the physicochemical properties of TiO2 for optoelectronic applications

This study investigated the influence of morphology on the physiochemical properties of TiO2, specifically comparing granule-like structures and nanofibers. Both morphologies were fabricated using different methods and characterized comprehensively. After annealing, X-ray diffraction confirmed their crystalline nature with peaks corresponding to the anatase phase of titania. Scanning electron microscopy revealed long nanofibers with diameters ranging from 62 nm to 95 nm, while the granules appeared as spherical or nearly spherical particles with sizes between 43 nm and 59 nm. Energy-dispersive X-ray analysis confirmed the presence of Ti and O in both structures. The Fourier-transform infrared and raman spectra exhibited characteristic bands related to the Ti–O–Ti stretching, vibrational, binding and anatase phase of titania, respectively. Raman peaks' intensity and position were influenced by crystal size, quality, and strain. The nanofibers showed higher raman mode peak intensities due to their larger surface area to volume ratio and high aspect ratio. In UV–Vis–NIR spectra, the nanofibers displayed higher absorption and a narrower bandgap than the granules. Hall Effect measurements indicated that the nanofibers had a higher carrier concentration and conductivity than the granules. Additionally, the nanofibers exhibited hydrophobic behavior with a water contact angle of 95°, while the granules were relatively hydrophilic with a contact angle of 58o. The findings could potentially facilitate the creation of customized TiO2 materials that are better suited for specific optoelectronic devices. This advancement would result in improved overall efficiency and performance across a range of technological uses.

Extensive function of green synthesized titania nanoparticles: Photodegradation of Congo red

Several extensive research studies have explored the advantages of green templates in the synthesis of structure and morphology-controlled photocatalytic nanomaterials. This paper compares the abilities of zingiber rhizome extract (ZE) and tapioca starch extracts (TS) in modifying the surface and optical properties of titania nanoparticles (TNP) synthesized by solgel technique. The synthesized nanocatalysts were characterized using various physicochemical techniques. While zingiber (ginger) extract effectively promotes the formation of dual anatase and rutile phases, tapioca extract supports formation of the single anatase phase of titania. These two extracts were examined for the degradation of Congo red in the presence of sunlight. The photomineralization and recyclability of catalysts were evaluated through total organic content analysis. The easy recovery and reusability of zingiber and tapioca biomasses, along with good control over the growth of nanoparticles, enable them to be implicit novel green templates in the successful synthesis of photoactive mesoporous nanotitania.

Europium decorated hierarchical TiO2 heterojunction nanostructure with enhanced UV light photocatalytic activity for degradation of toxic industrial effluent

Europium (Eu) doped cetyltrimethylammonium bromide (CTAB) surfactant assisted hierarchical TiO2 heterojunction nanostructure was synthesized by solvothermal method with ethanol as a solvent. The prepared nanostructure was subjected to various characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy dispersive spectrum (EDS) and Ultraviolet – diffuse reflectance spectroscopy (UV -DRS). The anatase phase of titania with its highly crystalline nature is confirmed by the XRD pattern. Crystallite sizes range from 4 to 10 nm according to XRD peak estimates. TEM and HRTEM studies are used to examine the prepared samples particle size and morphology. The elemental composition of the Europium (Eu) doped CTAB assisted TiO2 heterojunction nanostructure along with their corresponding band gap was estimated by EDS and UV-DRS studies respectively. The bandgap of the samples evaluated by UV–Visible spectroscopy are 3.40, 3.41 and 3.43 eV. The photocatalytic test was conducted in the presence of UV light and the amount of Congo red dye degradation increased with the time in the presence of the catalyst. After 75 min, it was discovered that the photocatalytic degradation efficiency was 97%. The photocatalytic effect depends heavily on the dispersion of the dopants.

Inexpensive production of hydrophobic and corrosion resistant titania-silica composite coatings for deep water sandwich pipe applications

ABSTRACT In this study, a multifunctional coating that may be both hydrophobic and corrosion-protective for aluminium sandwich pipes for deep sea applications is developed using the sol–gel dip-coating method. Tiania/silica composite gels were synthesised via sol–gel synthesis, and coatings were deposited on aluminium sandwich pipe substrates using a lab-manufactured dip-coater. XRD (X-Ray Diffractogram) analysis of the as-deposited coatings on the aluminium sandwich pipe revealed anatase phase of titania and amorphous nature of silica with a broad peak at Bragg angle 25°. Fourier transform infrared (FTIR) spectroscopy on the dip coated aluminium substrate revealed Si-O-Ti and Ti-O-Ti stretching vibrations at wavenumbers 906 cm−1 and 768 cm−1, respectively. Wetting investigation on the composite titania-silica coated aluminium substrate utilising the sessile drop technique supported the 123°Contact angle while interacting with a water droplet. Additionally, corrosion resistance examination on the coating was done using sodium chloride solution with salt spray test as per ASTM B117 and indicated no development of white and red rust on the dip coated composite titania-silica aluminium substrate.

Inexpensive hydrophobic and infrared reflective coatings on the cotton and silk fabrics using sol-gel dip coating technique

Several important practical applications, such as covid-19 front line worker garments and on-demand military apparel, require anti-water (hydrophobic) absorption and highly luminous clothing. Industrial and rapid production of these fabrics is highly expensive and under extensive research. In this work, we report an economical titania based superhydrophobic cotton and silk fabrics by wet chemical sol–gel dip coating technique. The structural characteristics of the textiles were studied using XRD, which revealed an anatase phase of titania. Wetting study on titania coated cotton and silk materials demonstrated contact angles of 146O and 136O, respectively. Additionally, in the ultraviolet and infrared wavelengths, diffused reflectance spectroscopy supported 84% and 92% reflectivity, respectively. As a result, the coated fabric proved to be an outstanding hydrophobic and reflective material that may be recommended for numerous maintenance-free apparel applications.

Room-temperature ferroelectric-like behavior in anatase TiO2 epitaxial films prepared by chemical solution deposition

Ferroelectrics of simple oxides have been of great interest due to they are easy to integrate with silicon semiconductors. The FE hysteresis loop was measured for the first time in pure anatase-phase titanium dioxide is reported, demonstrating that the ferroelectric-like behavior in a-TiO2 epitaxial thin films (7.5 nm to 228.8 nm) prepared by chemical solution deposition method on (001) SrTiO3 based substrates. Synchrotron based X-ray diffraction and reciprocal space mapping analysis prove that we have prepared high-quality epitaxial films. According to the results of the FE hysteresis loop, Pr can reach approximately 0.42 μC/cm2 in a-TiO2 film with a thickness of 14.5 nm. Furthermore, the PFM shows that the ferroelectric-like behavior is exhibited in a-TiO2 film of 7.5 nm and that the PFM polarization switch can be maintained for more than 100 min. All of these seem to indicate the presence of ferroelectric behavior in a-TiO2 films. We recognize that the origin of ferroelectric-like behavior is due to the distortion induced by strain and vacancy. However, since the polarization value is not very large and the PFM decays, the electrochemical effect has a non-negligible influence on the intrinsic ferroelectric performance.

Preparation and Photocatalytic Performance of Hollow Spherical TiO2/Cu2O Composites

The anatase phase titanium dioxide sols were prepared by hydrothermal method using titanium sulfate as the titanium source. Copper acetate monohydrate was used as the copper source, cubic phase Cu2O with matched bandgap TiO2 was introduced to synthesize hollow spherical nano-TiO2/Cu2O composites by precipitation method. The powder samples were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area testing (BET), X-ray electron spectroscopy (XPS) and ultraviolet and visible spectrophotometry (UV–Vis) diffuse reflectance spectroscopy analysis using methyl orange (MO) solution as indicator. The results showed that the introduction of Cu2O did not affect the physical phase of TiO2. Titanium dioxide was a shuttle-shaped nanorod with an average particle size less than 20[Formula: see text]nm, Cu2O was a sphere with an average particle size greater than 400 nm. TiO2 loading results in smaller particle size, larger specific surface area, thinner spherical walls, increased hollowness, and improved adsorption and photocatalytic properties of spherical Cu2O. The optimum Ti content of TiO2/Cu2O nanocomposite was 4.0 wt.%, the maximum specific surface area of TiO2/Cu2O sample was 90.57 m2/g with particle size less than 150 nm. When TiO2/Cu2O sample with Ti content of 4.0[Formula: see text]wt.% was used as photocatalyst, the adsorption effect was 66.2% under the dark reaction at 60[Formula: see text]min, the degradation effect was 91.2% under visible light irradiation at 120[Formula: see text]min. The adsorption and photocatalytic performance were excellent when the TiO2/Cu2O sample with Ti content of 4.0[Formula: see text]wt.% was used as the photocatalyst. This work provides an effective method for photocatalytic treatment of waste liquids.

P5 - Photocatalytic Activity and Antibacterial Behavior of Polyaniline-Doped Titanium Oxide Layers

The purpose of this study was to evaluate the effect of polyaniline doping of mixed anatase and rutile phase titanium oxide layers on the resulting photocatalytic activity (PCA) and antibacterial behavior. Commercially pure titanium grade 4 (CPTi) samples were divided into three groups: (1) anodized in 0.5 M sulfuric acid (control); (2) electropolymerized using cyclic voltammetry in a mixture of 0.5 M sulfuric acid and 0.25 M aniline after anodization in 0.5 M sulfuric acid (ACV); and (3) anodized in 0.5 M sulfuric acid and 0.25 M aniline (AAn). SEM, XRD, and water contact angles were used to evaluate the surface morphology, oxide layer crystallinity, and hydrophilicity of the oxide layers (n= 3). The PCA was determined through methylene blue (MB) degradation assay using 365 nm UVA illumination (n= 7). The antibacterial behavior was evaluated by assessing the reduction in percentage of S.aureus attachment under three UVA lighting conditions: (1) a pre-illumination group in which samples were irradiated under UVA light for one hour prior to bacteria exposure; (2) direct illumination group in which samples were irradiated for one hour after bacteria exposure; and (3) a no illumination group in which the samples were kept in the dark for one hour after bacteria exposure (n= 5). SEM confirmed the presence of polyaniline on AAN and ACV group surfaces. XRD confirmed the presence of anatase and rutile peaks for all groups with lower peak intensities for the AAn group. AAn, with an average contact angle of 29.7°, showed significantly higher hydrophilicity (p= 0.041) compared to the ACV and control groups with average contact angles of 46.4° and 47.9°, respectively. AAn showed significantly higher MB degradation at 60 minutes when compared to ACV (p= 0.034). Bacterial testing showed no significance differences between the three groups. However, an increased trend of bacterial attachment reduction was shown for the AAn and ACV groups, averaging 90.7% and 87.7%, compared to the control group, averaging 72.7%, under direct UVA illumination. Doping of polyaniline into the titanium oxide layer by direct anodization in sulfuric acid and aniline improves the hydrophilicity and photocatalytic activity of the titanium surfaces. Although polyaniline doped titanium oxide showed promising trends, no significant differences were shown in the antibacterial behaviors of the surfaces that were tested in this study. Additional studies using different concentration of aniline in the anodizing electrolyte are needed to attempt to improve photocatalytic activity and reduce bacterial attachment.

Plasma-Synthesized Nitrogen-Doped Titanium Dioxide Nanoparticles With Tunable Visible Light Absorption and Photocatalytic Activity

Abstract Titanium dioxide in its pure wide bandgap “white” form is a non-toxic, efficient, and practical photocatalyst, but predominately absorbs light in the ultraviolet range of the spectrum. The absorption range, however, can be extended into the visible by doping with oxygen vacancies or impurities, such as nitrogen, giving the material a black or brown appearance. To date, nitrogen-doped titanium dioxide has primarily been produced with approaches that require long processing times or multi-step synthesis protocols. Here, we present a fast (timescale of tens of milliseconds) all-gas-phase process, which enables the seamless tuning of the optical properties of titanium dioxide nanoparticles from white to brown. Titanium dioxide particles were synthesized through injection of tetrakis (dimethylamido)titanium (TDMAT), argon, and oxygen into a nonthermal plasma. The positions of the electrode and oxygen inlet relative to the precursor inlet are found to strongly influence particle properties. Variation of these parameters allowed for control over the produced particle optical properties from large bandgap (white) to small bandgap (brown). In addition, the particle microstructure can be tuned from amorphous to crystalline anatase phase titanium dioxide. The photocatalytic performance was tested under solar irradiation and amorphous particles exhibit the highest degree of photocatalytic decomposition of the dyes methyl orange and methylene blue.

Characterization of Titanium-Based Films Deposited by DC Sputtering Reactive on AISI 1018 Steel

The coated surfaces first layer Ti and second layer TiO2 as coating Nanostructured thin films of using DC sputtering on structural steel (AISI l018) and study characterization of coating SEM/EDS inspection shown a clearly perfect incorporation of layer by dc sputtering a granular structure of the layer with a variable hemisphere’s forms varied from 33 to 46 nm in size.X-XRD test complete for specimen indicates was found anatase phase titanium dioxide, the resulted coating layer of the target of Ti powders gives different morphology from the Ti layer alone The Specimens roughness average of coated Ti and TiO2with respectively was 4.831nm, 7.93 nm. Found that titanium layer will show a major part in increasing the bonding with improving the bond between the substrate steel AISI (1018) and the titanium oxide layer. The Vickers hardness increases when the coating with a layer of titanium with an oxygen content of ceramic layer is formed from 192.3 HV to 227 for Ti as well as important increase was detected in the Tio2 coating to 240 HV. In addition, Ti and Tio2 thin layer considered as a good barrier for hydrogen permeation through steel structure especially at cathode protection in pipelines.

(Invited) Pure Anatase Phase Titanium Dioxide Thin Films Prepared by Mist Chemical Vapor Deposition Applying for Photocatalysis

Up to date, titanium dioxide (TiO2) thin film has attracted considerable interest as the most promising material for a variety of applications and products in the environmental and energy fields, including self-cleaning surfaces, air and water purification systems, and photoelectrochemical conversion because of its outstanding chemical stability and electrical properties, etc [1]. Among the three phases of TiO2, anatase TiO2 has higher photocatalytic activity than rutile and brookite TiO2. Anatase TiO2 films can be synthesized by various methods. However, there were still issues on synthesizing the stable pure anatase phase TiO2 using different methods. Compared with other reported methods, the mist chemical vapor deposition (mist CVD) [2] is an alternative method to synthesize TiO2 thin films, by which the growth of oxide thin film can be precisely controlled according to our previously research [3]. In this research, anatase TiO2 thin films were fabricated on glass by mist CVD method. The precursor solution (150 ml) was prepared by dissolving acetylacetone (0.9 ml) and titanium tetraisopropoxide (TTIP, 0.9 ml) in water and methanol. In order to investigate the temperature on structural, optical and photocatalytic properties of TiO2 films, the deposition temperature were set at room temperature, 200˚C and 400˚C for comparison. During the mist CVD process, mist droplets were generated from the precursor solution by ultrasonic atomization at 2.4 MHz and transferred to the reaction chamber by N2 carrier gas. The structural properties of TiO2 thin films were investigated by X-ray diffraction , Raman spectroscopy and scanning electron microscope, atomic force microscope . The optical properties of TiO2 thin films were investigated by transmittance spectroscopy.According to the morphological analysis, TiO2 films of 300nm with uniform surface were observed from the deposition temperature of 400˚C. There was no thin film at room temperature and some isolated particles observed at 200˚C. Examining the GIXRD patterns of TiO2 films deposited at 400˚C, the following diffraction peaks (101), (004), (200), (211), (201), (204) and (215) were observed, which corresponds to the diffraction peaks of anatase phase TiO2. The transmittance of TiO2 films was higher than 75 % in the visible region. The photocatalytic efficiency of TiO2 film showed the photocatalytic efficiency due to a maximum number of {001} facets and a large surface area.In summary, the pure anatase phase TiO2 thin films could be synthesized at 400˚C by mist CVD method. The obtained anatase TiO2 films showed high photocatocatalytic efficiency. The growth mechanism of pure anatase TiO2 films will be revealed in the paper.References V. Baryshnikova, L. A. Filatov, A.S. Petrov, and S. E. Alexandrov, Chemical Vapor Deposition, 21, 327-333 (2015).Kawaharamura, K. Mori, H. Orita, T. Shirahata, S. Fujita, and T. Hirao, Japanese Journal of Applied Physics, 52, 035501 (2013). Li, C. Li, T. Kawaharamura, D. Wang, N. Nitta, M. Furuta, H. Furuta, and A. Hatta, Transactions of the Materials Research Society of Japan, 39[2], 161-164 (2014).

(Invited) Pure Anatase Phase Titanium Dioxide Thin Films Prepared by Mist Chemical Vapor Deposition Applying for Photocatalysis

Pure anatase TiO2 thin films were successfully deposited on five kind of substrates including p-type silicon, AZO, ITO, glass, and quartz class substrates by mist CVD method. The deposited temperature to get the pure anatase TiO2 thin film was optimized at 400°C. The intertwined nanosheets structure of TiO2 thin films with uniformity were observed on all of different substrates. The deposited TiO2 thin films on five kind of substrates could be confirmed that the pure anatase TiO2 with the same dominant peak of (101) and crystallinity was significantly improved in order of p-type silicon, AZO, ITO, glass, and quartz glass substrates. The transmittance of TiO2 films on transparent substrates showed the high transmittance of over 65% in visible region. The pure anatase TiO2 film on AZO substrate with lowest roughness had the greater potential to apply in photocatalytic applications.

Influence of TiO2/GO weight ratio on the structure, mechanical, and electrical properties of SiO2–Al2O3 glass–ceramics

Glass–ceramics of the SiO2–Al2O3–TiO2-GO quaternary system was successfully prepared by sol–gel technique. The effects of TiO2/GO weight ratios on the structure and physical properties of glass–ceramics have been extensively examined. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) have been used to characterize and identify the structural phase as well as the surface morphology of all samples. The crystalline phases of all prepared samples exhibited anatase phase of titania (Tetragonal: TiO2). But with increasing the amount of Graphite the phase of GO appeared. The thermal properties of the samples have been studied using thermal analysis, differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) technique. The electrical properties have been enhanced with increased TiO2/GO weight ratios up to 1.25, and its electrical conductivity and dielectric constant were 6 × 10–10 S/cm and 9.95, respectively, at frequency 1 MHz. In addition, mechanical properties including density, hardness, and wear rates were measured. The experimental data depicted that, the micro-hardness reached a maximum value of approximately 14 GPa at 2.50 GO wt. %. While the wear rate has a value of nearly 53 × 10–5 mm3/Nm, this is very small paralleled to other glass–ceramics. Besides, good machinability index (m = 0.23) can be a good candidate for machinability applications.

Fabrication of Mesoporous PdO–TiO2 Nanocomposites with Superior Photonic Efficacy Concerning Photo-Destruction of the Herbicide Imazapyr

In this probe, a convenient template was practiced to fabricate mesoporous PdO–TiO2 nanocomposites using a sol–gel routine. Photo-destruction of the herbicide imazapyr was adapted to figure out the photonic efficacies of the formulated nanocomposites. Furthermore, the appraised photonic efficacies were correlated with the photonic efficacies retained by commercial P25 Degussa as well as mesoporous titania. Progression of the tetragonal anatase phase of titania was entrenched via X-ray diffraction inquire. PdO–TiO2 nanocomposite accommodating 0.9% PdO possessed superlative photonic efficacy of 34.8% whereas, commercial P25 Degussa and mesoporous titania possessed photonic efficacies of 1.0 and 2.0% respectively revealing the superior photonic efficacy of the fabricated nanocomposites in comparison to other relevant photo-catalysts. In conclusion, PdO–titania nanocomposites acquiring enhanced charge carriers’ separation could be fabricated along with the collaborating action of both titania and PdO nanoparticles. Furthermore, the tremendous stability of the fabricated nanocomposites was ascertained via its implementation up to five cycles keeping its photo-catalytic performance without alteration. Hence, PdO nanoparticles could be formulated as fruitful promoters for the photo-catalytic aspects possessed by mesoporous titania.

Electrodeposition Assisted Formation of Anodized TiO2-CuO Heterojunctions for Solar Water Splitting

The anatase phase titanium dioxide nanotubes (ATNTs) is investigated for photocatalytic water splitting in pristine form and after copper oxide (CuO) incorporation. ATNTs are grown using titanium substrate by one and two step anodization followed by annealing at 450 ºC for transformation to anatase phase. Both of the anodization steps are performed by electrochemical process using ammonium fluoride, ethylene glycol and deionized water as electrolyte. The ATNTs are then modified with CuO nanoparticles, electrochemically and also through dip-coating process. The growth of ATNTs and deposition of CuO nanoparticles is confirmed with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. Well organized and vertically aligned nanotubes are confirmed under FESEM. Linear Sweep Voltammetry (LSV) technique is performed for photocurrent responses in distilled water in the dark environment as well as in the light of solar simulator at applied potential of 1.0V. ATNTs grown with two steps anodization offered promising results for photocatalytic water splitting compared to single step anodization. The CuO modification in ATNTs shown a reasonable increase in photocurrent densities compared to pristine ATNTs. Moreover, the ATNTs modified with CuO through electrochemical deposition exhibited greater photocurrent responses than the dip coating method. Figure 1

Electrodeposition-assisted formation of anodized TiO2–CuO heterojunctions for solar water splitting

The anatase phase titanium dioxide nanotubes (ATNTs) are investigated for photocatalytic water splitting with and without the formation of copper oxide (CuO) heterojunctions. ATNTs have been grown on titanium substrate by one- and two-step anodization, followed by annealing at 450 oC for transformation to anatase phase. Anodization was performed in an electrolyte containing ammonium fluoride, ethylene glycol and deionized water. The ATNTs were then modified with CuO nanoparticles by dip-coating and electrochemical deposition. The growth of ATNTs and incorporation of CuO nanoparticles in it were confirmed with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) spectroscopy. Well-organized and vertically aligned nanotubes were observed in the FESEM results. Contact angle measurements proved that the thin film of nanotubes is hydrophilic in nature. Linear sweep voltammetry (LSV) technique was performed for photocurrent responses, using distilled water in the dark environment as well as in the light of solar simulator at applied potential of 1.0 V. The photocurrent densities in the dark were negligible, while it became significant under the influence of simulated visible light. The ATNTs grown with two-step anodization offered promising results for photocatalytic water splitting compared to single-step anodization. The CuO modification in ATNTs exhibited a reasonable increase in photocurrent densities compared to pristine ATNTs. Furthermore, the electrochemical deposition process for modification of ATNTs with CuO afforded much better photocurrent responses compared to the dip coating method. The electrochemical deposition of CuO in ATNTs was performed at 0.7 V, 0.9 V and 1.1 V, among which the sample prepared at 0.7 V exhibited the highest photocurrent densities.

Titanium Dioxide-Coated Zinc Oxide Nanorods as an Efficient Photoelectrode in Dye-Sensitized Solar Cells.

Well-arrayed zinc oxide nanorods applied as photoelectrodes for dye-sensitized solar cells were synthesized on an aluminum-doped zinc oxide substrate by the multi-annealing method. In order to improve the chemical stability and surface-to-volume ratio of photoanodes in dye-sensitized solar cells, the synthesized zinc oxide nanorods were coated with pure anatase phase titanium dioxide film using a novel mist chemical vapor deposition method. The effects of the titanium dioxide film on the morphological, structural, optical, and photovoltaic properties of zinc oxide–titanium dioxide core–shell nanorods were investigated. It was found that the diameter and surface-to-volume ratio of zinc oxide nanorods were significantly increased by coating them with titanium dioxide thin film. The power conversion efficiency of dye-sensitized solar cells was improved from 1.31% to 2.68% by coating titanium dioxide film onto the surface of zinc oxide nanorods.