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Based on the independent ultrasonic atomised pyrolytic spraying device, an electrostatic field coupling is carried out by applying non-uniform electric field between the upper and lower walls of the reactive deposition chamber. Then, the effect of applied DC voltage on the structure and properties of the sprayed TiO2 thin film was conducted. Upon the action of the electric field, the droplet particles are polarized and gain momentum perpendicular to the substrate surface. The Coulomb force produced by electric field cancels the influence of the thermophoresis force, and then improves the adhesion efficiency of titanium precursor on the near surface of the substrate. Thus, the crystallization property and film formation uniformity of the film is greatly enhanced. The results show that when the applied voltage is 1. 0 kV, the anatase TiO2 thin film is optimized. Its (101) crystal plane has a full width at half maximum of 0. 29°, an average grain size of 94. 19 nm, an average visible light transmittance of 85% and a surface roughness of 16. 70 nm. By applying electrostatic fields, the momentum of incident particles near the surface of the substrate is regulated and a stable environment more conducive to the growth of TiO2 thin film is constructed. This work provides a reference for the optimization of TiO2 thin film preparation process. [ABSTRACT FROM AUTHOR]

Realizing transformation from transparent insulating to transparent conducting, is a pursuing goal in designing and fabricating novel optoelectronic materials and devices. Here, a pronounced insulating to metal transition in anatase TiO2 thin films is achieved through ionic liquid gating, and interestingly the material maintains an invariable high optical transparency. It is revealed that the emergent metallic state can be attributed to the electron doping associated with the hydrogen ion intercalation. Importantly, the hydrogenation leads to the almost rigid shift of the Fermi energy and therefore maintains nicely the transparency at the visible light region. This result is in strong contrast with the case of oxygen vacancy doping, in which the optical bandgap is suppressed due to improved orbitals hybridization and intraband transition. Moreover, through synergistic ion‐electron doping, the selective control of the gating area and pattern is realized in the micrometer or even nanometer scale with extremely distinct physical properties, which can be employed to fabricate novel optical and electronic devices. The result greatly deepens the understanding of the underlying physics and formation mechanism of transparent conducting oxide (TCO) materials. It is envisioned that this work would provide a new pathway to design other potential optoelectronic materials with novel functionalities. [ABSTRACT FROM AUTHOR]

The present study examines the impact of acidic and basic pH on the optical, morphological, and structural characteristics of TiO2 sol–gel thin films that are deposited using the dip-coating technique on glass substrates. All of the samples are polycrystalline and have anatase structures with preference orientation along the (101) direction, according to X-ray diffraction (XRD) and Raman spectroscopy (RS). It is observed that, for both basic and acidic pH values, crystallite size decreases as sol pH rises. All of the films' surfaces were smooth and had a uniform grain distribution, according to atomic force microscopy (AFM). The pH of the sol has an impact on the surface roughness. All films had a higher degree of transparency, according to UV-visible spectroscopy. The refractive index and the direct and indirect band gaps are two essential optical properties of thin films that are significantly influenced by the pH of the deposition medium. Measurements of photoluminescence (PL) showed a strong violet-blue emission band, the intensity of which is highly dependent on the sol's pH. In acidic media, PL decreases with increasing pH. However, in a basic environment, the PL rises sharply as the pH increases from 10 to 11 and then decreases for higher pH values. In particular, compared to the other samples, the emission intensity from the film deposited at a pH value of 10 is noticeably lower and displays unique spectral signatures. Highlights: The effects of acidic and basic pH on the structural, morphological, and optical properties of TiO2 sol–gel thin films were investigated. XRD analyses show that crystallite size decreases with increasing pH in both acidic and basic sols. Optical analysis demonstrates that TiO2 thin films deposited at acidic pH values have greater transparency than those deposited at basic pH values. Photoluminescence measurements revealed a strong correlation between sample emission and pH. The film deposited at pH 10 has significantly lower emission intensity and a distinct spectral signature than the other samples. [ABSTRACT FROM AUTHOR]

In the present work, we used a pulsed laser deposition technique to embed TiO2 nanostructure on porous silicon substrates using a pulsed laser deposition process. Nanocrystalline porous silicon was synthesized using the photo-assisted electrochemical method. The study analyzed the optoelectronic characteristics of double junctions of TiO2/PS/n-Si structures as well as the PS/n-Si structure. We investigated the properties of TiO2/PS/n-Si and PS/n-Si structures, focusing on their structural, optical, and electrical features under ambient conditions. The XRD measurement indicated the formation of the anatase and rutile tetragonal phases with the preferred orientation anatase (101) plane in the prepared sample. The mean sizes of The TiO2 nanostructures deposited onto porous silicon substrates range from 45.97 to 109.23 nm. The degree of pore filling depends upon the laser fluences employed, varying from moderate to close to complete packing. The optical properties of TiO2/PS/n-Si structures showed decreasing reflectance after depositing on porous silicon. The TiO2 nanostructure produced on porous silicon exhibits five different spectra in the UV and visible range, as displayed in the room-temperature photoluminescence analysis. The current density–voltage characteristics of formed samples in dark and photoilluminated conditions are examined at room temperature. The properties of the TiO2/PS/n-Si structure enhance those of the PS/n-Si device. The highest specific detectivity of the TiO2/PS/n-Si devices is 32.45 × 1010 Jones in the visible region, while the ultraviolet region is 30.04 × 1010 Jones. The TiO2/PS/n-Si photodetectors possess an optimal relative quantum efficiency of 80.1% in the near UV region, whereas, in the visible range, the values of relative quantum efficiency are 51.8% at 531 nm and 54.5% at 634 nm. The findings reveal that formed photodetectors exhibit UV and visible light sensitivity after depositing TiO2 layers on porous silicon. However, the photodetectors produced using TiO2 nanostructures placed on porous silicon demonstrate greater sensitivity than those made from as-synthesized porous silicon. [ABSTRACT FROM AUTHOR]

Abstract Realizing transformation from transparent insulating to transparent conducting, is a pursuing goal in designing and fabricating novel optoelectronic materials and devices. Here, a pronounced insulating to metal transition in anatase TiO2 thin films is achieved through ionic liquid gating, and interestingly the material maintains an invariable high optical transparency. It is revealed that the emergent metallic state can be attributed to the electron doping associated with the hydrogen ion intercalation. Importantly, the hydrogenation leads to the almost rigid shift of the Fermi energy and therefore maintains nicely the transparency at the visible light region. This result is in strong contrast with the case of oxygen vacancy doping, in which the optical bandgap is suppressed due to improved orbitals hybridization and intraband transition. Moreover, through synergistic ion‐electron doping, the selective control of the gating area and pattern is realized in the micrometer or even nanometer scale with extremely distinct physical properties, which can be employed to fabricate novel optical and electronic devices. The result greatly deepens the understanding of the underlying physics and formation mechanism of transparent conducting oxide (TCO) materials. It is envisioned that this work would provide a new pathway to design other potential optoelectronic materials with novel functionalities.

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

TiO2 thin films were deposited on glass substrates through magnetron sputtering using a Ti target and an Ar-O2 gas mixture, with different electrical currents ranging from 0.2 to 0.6 A. The impact of varying the current on the structure and properties of the TiO2 films was investigated in a systematic manner through techniques such as X-ray diffraction (XRD), scanning electron microscopy with field emission gun (SEM-FEG), Raman spectroscopy, and visible ultraviolet spectroscopy (UV/Vis). The XRD results indicated the presence of both anatase and rutile phases, with the intensities of these phases increasing as the electrical current increased. Furthermore, the crystallinity, particle size, transmittance, and interference fringes were observed to increase as the electrical current was raised. [ABSTRACT FROM AUTHOR]

Sel surya perovskite merupakan sel surya yang memanfaatkan proses fotoelektrokimia dalam mengubah energi foton menjadi energi listrik, yang ramah lingkungan, fabrikasi mudah, dan biaya penelitian rendah. Penelitian ini difokuskan pada penentuan variasi ketebalan dari lapisan film tipis TiO2 sebagai ETL serta pengaruhnya terhadap sifat optik dan sifat listrik pada sel surya perovskite. Karakterisasi sifat optik diperoleh dari hasil absorbansi menggunakan UV-Vis Spectrophotometer, sedangkan karakterisasi sifat listrik meliputi nilai ???, ??, ???, dan ? menggunakan Standard Solar Simulator 1.5 AM. Hasil variasi ketebalan lapisan TiO2 sebesar 41,75 µm, 28,50 µm, 19,00 µm, dan 10,00 µm berdasarkan kecepatan spin coating 3000 rpm, 4000 rpm, 5000 rpm, dan 6000 rpm selama 20 detik yang menghasilkan formulasi setiap 1 rpm dari spin coating dihasilkan ketebalan sebesar -0,0105 + 71,95 µm. Nilai absorbansi tertinggi sebesar 2,83 a.u didapatkan pada sampel dengan ketebalan 41 µm. Nilai efisiensi tertinggi sebesar 1,26 x 10-7% pada sampel dengan ketebalan 10 µm, dengan nilai ??? 0,30 x 10-6 mA/cm2, ??? 0,0656 V, FF 23 %. Sifat listrik dari sel surya perovskite dipengaruhi oleh ketebalan lapisan TiO2, semakin tipis lapisan TiO2 semakin tinggi nilai efisensi yang dihasilkan.

Titanium dioxide (TiO2) in the form of thin films has attracted enormous attention for photocatalysis. It combines the fundamental properties of TiO2 as a large bandgap semiconductor with the advantage of thin films, making it competitive with TiO2 powders for recycling and maintenance in photocatalytic applications. There are many aspects affecting the photocatalytic performance of thin film structures, such as the nanocrystalline size, surface morphology, and phase composition. However, the quantification of each influencing aspect needs to be better studied and correlated. Here, we prepared a series of TiO2 thin films using a sol-gel process and spin-coated on p-type, (100)-oriented silicon substrates with a native oxide layer. The as-deposited TiO2 thin films were then annealed at different temperatures from 400 °C to 800 °C for 3 h in an ambient atmosphere. This sample synthesis provided systemic parameter variation regarding the aspects mentioned above. To characterize thin films, several techniques were used. Spectroscopic ellipsometry (SE) was employed for the investigation of the film thickness and the optical properties. The results revealed that an increasing annealing temperature reduced the film thickness with an increase in the refractive index. Atomic force microscopy (AFM) was utilized to examine the surface morphology, revealing an increased surface roughness and grain sizes. X-ray diffractometry (XRD) and UV-Raman spectroscopy were used to study the phase composition and crystallite size. The annealing process initially led to the formation of pure anatase, followed by a transformation from anatase to rutile as the annealing temperature increased. An overall enhancement in crystallinity was also observed. The photocatalytic properties of the thin films were tested using the photocatalytic decomposition of acetone gas in a home-built solid (photocatalyst)–gas (reactant) reactor. The composition of the gas mixture in the reaction chamber was monitored using in situ Fourier transform infrared spectroscopy. Finally, all of the structural and spectroscopic characteristics of the TiO2 thin films were quantified and correlated with their photocatalytic properties using a correlation matrix. This provided a good overview of which film properties affect the photocatalytic efficiency the most. [ABSTRACT FROM AUTHOR]

In this work, an eco-friendly sol-gel synthesis of pure and doped TiO2, previously developed at lab-scale, is applied in three different environmental applications at lab-scale and then, upscaled towards industrial applications. For each application, the TiO2 is used as a coating deposited mainly on steel substrates. The three applications are: (i) the development of a photocatalytic reactor made of a UV lamp, an ozonation part and a TiO2 photocatalytic coating to treat water from swimming pools, (ii) the development of a new generation of low energy sterilizers by an advanced oxidation process using a photocatalytic coating illuminated by a blue LED, and (iii) an easy-to-clean coating for outdoor steel. In each application, the up-scale results were similar to those obtained in the laboratory with respect to the crystallinity, the visual aspect, the hydrophilicity, and the photocatalytic properties of the produced coatings. These developments showed the possibility to bring sol-gel TiO2 products outside the laboratory towards pilot and industrial applications, and opens the way for many possible up-scaled sol-gel based environmental applications. Highlights: Eco-friendly sol-gel synthesis of pure and doped TiO2 developed for industrial applications. TiO2 is deposited on steel substrates for three applications. TiO2 coatings used for decontamination of swimming pool and fountain waters. TiO2 layer also used as easy-to-clean coating for outdoor pre-painted steel. The efficiency of the layers is successfully up-scaled from laboratory to industrial applications. [ABSTRACT FROM AUTHOR]

Wastewater treatment targeting reuse may limit water scarcity. Photocatalysis is an advanced oxidation process that may be employed in the removal of traces of organic pollutants, where the material choice is important. Titanium dioxide (TiO2) is a highly efficient photocatalyst with good aqueous stability. TiO2 powder has a high surface area, thus allowing good pollutant adsorption, but it is difficult to filter for reuse. Thin films have a significantly lower surface area but are easier to regenerate and reuse. In this paper, we report on obtaining sol-gel TiO2 thin films on spherical beads (2 mm diameter) with high surface area and easy recovery from wastewater. The complex influence of the substrate morphology (etched up to 48 h in concentrated H2SO4), of the sol dilution with ethanol (1:0 or 1:1), and the number of layers (1 or 2) on the structure, morphology, chemical composition, and photocatalytic performance of the TiO2 thin films is investigated. Etching the substrate for 2 h in H2SO4 leads to uniform, smooth surfaces on which crystalline, homogeneous TiO2 thin films are grown. Films deposited using an undiluted sol are stable in water, with some surface reorganization of the TiO2 aggregates occurring, while the films obtained using diluted sol are partially washed out. By increasing the film thickness through the deposition of a second layer, the roughness increases (from ~50 nm to ~100 nm), but this increase is not high enough to promote higher adsorption or overall photocatalytic efficiency in methylene blue photodegradation (both about 40% after 8 h of UV-Vis irradiation at 55 W/m2). The most promising thin film, deposited on spherical bead substrates (etched for 2 h in H2SO4) using the undiluted sol, with one layer, is highly crystalline, uniform, water-stable, and proves to have good photocatalytic activity. [ABSTRACT FROM AUTHOR]

Undoped and metal doped nanocrystalline TiO 2 transparent thin films were synthesized on glass substrates via sol-gel/dip-coating method. TiO 2 thin film coatings can be applied to the surfaces of solar panels to impart self-cleaning properties to them. The structural and optical properties of few nanometer-thick films were characterized by XRD, SEM, CA, AFM, XPS, and UV–Vis spectrophotometry techniques. The stoichiometric TiO 2 films crystallized in anatase phase, with a particle size of ∼100 nm, which were uniformly distributed on the surface. The prepared films with a roughness of ∼1–5 nm, increased the hydrophilicity of the glass surface. Reducing the amount of Ti precursor (X) favored the improvement of film quality. To improve the photocatalytic activity of the TiO 2 thin film, it was doped with Ni, Cd, Mo, Bi and Sr metal ions. The effect of metal doping on the photocatalytic activity of the films was investigated using the degradation process of methylene blue (MB) dye as the model contaminant. Among the prepared coatings, the Sr–TiO 2 film showed the highest efficiency for MB degradation. It increased the dye degradation efficiency of the films under both UV and Vis lights. The kinetic investigations also showed that the degradation of MB by TiO 2 and M − TiO 2 films obeyed the pseudo-first order kinetics. [Display omitted] • TiO 2 and metal-doped TiO 2 thin films were prepared via sol-gel/dip coating method. • Conditions for obtaining highly transparent superhydrophilic films were decided. • Photocatalytic activity of the films was proved in the MB dye degradation process. • Sr doping (Sr–TiO 2) improved the photocatalytic activity of the prepared coatings. • The films can be applied on solar panel covers as self-cleaning coatings. [ABSTRACT FROM AUTHOR]

A highly selective and sensitive EGFET-pH sensor based on composite TiO2–PANI had been developed in this work. A sol-gel titanium dioxide (TiO2) and the composite of TiO2 with semiconducting polyaniline (PANI) were deposited using a simple spin-coating method on an indium tin oxide (ITO) substrate. The films have been explored as a sensing electrode (SE) of extended gate field-effect transistor (EGFET) for pH applications in the range of pH 2 to 12. The pH sensitivities between TiO2, TiO2–PANI bilayer composite, and TiO2–PANI composite thin films were discussed. Among these, the TiO2–PANI composite thin film showed a super-Nernstian behavior with high sensitivity of 66.1 mV/pH and linearity of 0.9931; good repeatability with a standard deviation of 0.49%; a low hysteresis value of 3 mV; and drift rates of 4.96, 5.54, and 3.32 mV/h in pH 4, 7, and 10, respectively, for 6 h. Upon applying the TiO2–PANI composite as the SE for nitrate measurement, low sensitivity of 12.9 mV/dec was obtained, indicating that this film is a highly selective sensing electrode as a pH sensor. The surface morphology and crystallinity of the thin films were also discussed. [ABSTRACT FROM AUTHOR]

TiO2 film has the advantage of good photochemical stability and it can be used for self-cleaning glasses. However, due to the wide band gap, the spectral response range of TiO2 film is restricted to the ultraviolet region. In this work, based on the research of TiO2 thin films, multilayer TiN/Ag/Cu2O/TiO2 films were designed and successfully prepared. The structure and properties of the obtained samples were characterized by X-ray diffraction, spectral ellipsometry (SE), atomic force microscopy (AFM) and UV-Vis-NIR spectrophotometer. The results show that p-n heterojunction will be formed between Cu2O and TiO2 in the multilayer film, thus reducing the band gap of TiO2 film. Based on the analysis of the photocatalytic mechanism of the multilayer films, a conclusion may be drawn that the designed multilayer film is helpful to improve the photocatalytic efficiency of titanium dioxide and expand its utilization of sunlight.

Thin films of titanium dioxide (TiO 2), with thicknesses ranging from 105 to 231 nm, were deposited on glass substrates using radio-frequency (RF) magnetron sputtering in an argon atmosphere at four distinct RF power levels: 40, 70, 100, and 130 W, with the deposition time kept constant. The crystalline structure, surface morphology and optical and semiconductor properties of the obtained films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and UV–visible transmittance spectroscopy. These analyses revealed that the crystallinity of the films improves with increasing RF power, corresponding to an increase in film thickness. Consequently, the samples transition from poorly crystalline or amorphous structure to a monocrystalline rutile phase with a (110) texture. However, at the highest RF power studied, this texture is partially disrupted by the formation of nanocrystals with different orientations. The surface roughness exhibited multifractal characteristics, with complexity systematically decreasing and surface stiffness reducing as RF power increased. Refractive indices and optical band gap energies were determined using the Swanepoel and Tauc plot methods, respectively. The films exhibited a notable increase in the refractive index and a decrease in the optical band gap, from 3.81 eV to 3.52 eV, as the RF power was increased. This underscores the influence of RF power on the optical and semiconductor properties of TiO 2 films. [Display omitted] • TiO 2 thin films were deposited on glass substrates using RF magnetron sputtering to study the impact of varying RF power on their properties. • Increasing RF power enhanced the crystallinity and modified the crystalline texture of the TiO 2 thin films. • The films exhibited multifractal surface roughness, with complexity and surface stiffness decreasing systematically as RF power increased. • Refractive indices increased notably with increasing RF power, while the optical band gap energy decreased under the same conditions. [ABSTRACT FROM AUTHOR]

The synthesis of active thin films supported on substrates overcomes the drawbacks of powder-based photocatalysis and energy harvesting. In this study, semiconducting thin films of pristine TiO2 and Sn doped TiO2 were coated on glass substrates by the sol–gel dip-coating method. The effect of both annealing temperature (450 and 500 °C, during 2 h in air atmosphere) and Sn dopant content (1, 3 and 5 at.%) on the structural, morphological and optical properties of Sn doped TiO2 films were studied. The correlation between these properties and the photocatalytic performance of the films in the removal of Rhodamine B solution under UV light was investigated. At 450 °C, Sn:TiO2 films exhibit anatase–brookite mixed phase, while at 500 °C, the films exhibit anatase phase. The crystallites sizes of the films were on a nanometer scale, between 19.01 and 26.57 nm. The pristine TiO2 film treated at 450 °C has a compact morphology with spherical grains, and after adding different Sn content, the nano-spheres turn into nanorods. At 500 °C, all the films illustrate a porous morphology with spherical grains. The two series are transparent in the visible region and have an optical band gap of 3.23–3.54 eV. The (e−/h+) recombination rate of TiO2 film decreases as a function of Sn doping. The latter enhances the photocatalytic efficiency of porous TiO2 film and 1 at.% Sn:TiO2 exhibits the highest degradation rate, which can be attributed to a larger surface area and less (e−/h+) recombination rate. [ABSTRACT FROM AUTHOR]

A super-hydrophilic pH-sensitive electrode with a porous TiO2 thin film is proposed in this work and fabricated using the chemical etching method. In total, 30 groups of porous TiO2 thin film were obtained by immersing a Ti sheet in NaOH, with the solution concentration ranging from 0.5–4 M and the reaction time ranging from 15–240 min. SEM, XRD, XPS, and a contact angle meter were used to investigate the influence of the chemical etching parameters on the morphology, composition, and wettability of the fabricated electrodes. The chemical etching parameters were found to have a significant influence on the specific surface area and the component of the films, which strongly affected the wettability and pH sensing characteristics of the electrodes. The electrode obtained with a solution concentration of 1 M and reaction time of 120 min is the ideal product because of its excellent wettability, with a contact angle of 5.46°, and good pH sensing characteristics in pH buffer solutions. The electrode also showed good stability regarding its wettability and pH sensing properties during storage and utilization. [ABSTRACT FROM AUTHOR]

In this work, effects of TiO2 contribution together with two different doping as graphene oxide (GO) and rubidium fluoride (RbF) are investigated at the interface of Au/n-Si metal–semiconductor (MS) diode. Diode characteristics are mainly evaluated from current–voltage measurements and values of barrier height and ideality factor are compared to the diodes with and without doping in interface layer. Although existence of interface layer increases these values, there is a decrease with adapting GO and RbF to the TiO2 structure. In addition, series and shunt resistance values are calculated with interface layer, and resistance effect is also discussed by Norde's and Cheung's functions. Forward biased carrier transport mechanism is evaluated under the presence of interface states by thermionic emission model and density of interface trap states is also discussed. At the reverse biased region, field effected thermionic emission model is found to be dominant flow mechanism, and leakage current behavior is explained by Schottky effect. Solar simulator with different illumination intensities is used to investigate photo-generated carrier contribution and photo-response of the diodes. [ABSTRACT FROM AUTHOR]

The adsorption characteristics were studied at room temperature (RT) of tetrakis(dimethylamido)titanium (TDMAT) and titanium chloride (TiCl4) on the Si(100)-2 × 1 surface in atomic layer deposition (ALD) of titanium dioxide (TiO2). Density functional theory (DFT) with the B3LYP/6-31G(d,p) level through Gaussian 09 was used to calculate the adsorption characteristic and the mechanism of surface reaction. The potential energy profile was evaluated to investigate the reaction mechanisms. All the states in the adsorption step were found below the reactant level, indicating that the TDMAT molecule is adsorbed on the silicon surface spontaneously at RT. The reaction mechanisms were started by breaking of O–H bond, followed by breaking the Ti–N and Ti–O bonds, respectively. To clarify the reaction mechanism in the adsorption step, the transition state was divided into two sub-stages, namely the O–H break (TS1) and the Ti–N break (TS2). In addition, the initial adsorption of TiCl4 on the hydroxylated silicon surface was calculated. The reaction mechanism and the energy profile of TDMAT and TiCl4 were discussed. [ABSTRACT FROM AUTHOR]

TiO2 thin films are promising as photocatalysts to decompose organic compounds. In this study, TiO2 thin films were deposited by reactive radio-frequency (RF) magnetron sputtering under various flow rates of oxygen and argon gas. The results show that the photocatalytic activity decreases as the oxygen-gas ratio is increased to 30% or less, while the activity increases under oxygen-rich conditions. It was observed that the crystal structure changed from anatase to a composite of anatase and rutile, where the oxygen-gas ratio during RF sputtering is more than 40%. Interestingly, the oxygen vacancy concentration increased under oxygen-rich conditions, where the oxygen-gas ratio is more than 40%. The sample prepared under the most enriched oxygen condition, 70%, among our experiments exhibited the highest concentration of oxygen vacancy and the highest photocatalytic activity. Both the oxygen vacancies and the composite of anatase and rutile structure in the TiO2 films deposited under oxygen-rich conditions are considered responsible for the enhanced photocatalysis. [ABSTRACT FROM AUTHOR]

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A highly selective and sensitive EGFET-pH sensor based on composite TiO2–PANI had been developed in this work. A sol-gel titanium dioxide (TiO2) and the composite of TiO2 with semiconducting polyaniline (PANI) were deposited using a simple spin-coating method on an indium tin oxide (ITO) substrate. The films have been explored as a sensing electrode (SE) of extended gate field-effect transistor (EGFET) for pH applications in the range of pH 2 to 12. The pH sensitivities between TiO2, TiO2–PANI bilayer composite, and TiO2–PANI composite thin films were discussed. Among these, the TiO2–PANI composite thin film showed a super-Nernstian behavior with high sensitivity of 66.1 mV/pH and linearity of 0.9931; good repeatability with a standard deviation of 0.49%; a low hysteresis value of 3 mV; and drift rates of 4.96, 5.54, and 3.32 mV/h in pH 4, 7, and 10, respectively, for 6 h. Upon applying the TiO2–PANI composite as the SE for nitrate measurement, low sensitivity of 12.9 mV/dec was obtained, indicating that this film is a highly selective sensing electrode as a pH sensor. The surface morphology and crystallinity of the thin films were also discussed.

In this present work, we have studied the effect of organic solvents and acetylacetone (Acac) molar ratio on several properties of TiO2 thin films prepared by pneumatic spray pyrolysis (SP). The TiO2 thin films were characterized by the following techniques including the following: X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM) and UV–visible spectrophotometer. The XRD results showed pure anatase TiO2 thin films with preferential orientation (101) plan, the crystallite size varying between 14.72 and 35.12 nm. The Raman spectroscopy confirmed the formation of the only phase of TiO2 (anatase). The morphological properties were investigated by SEM. The UV–Visible spectrophotometer showed the semiconducting properties of anatase TiO2, and the optical band gap was ranged between 3.17–3.34 eV. The refraction index, the extinction coefficient and the porosity were estimated using transmittance values. The TiO2 thin films have had good properties. They were prepared by low-cost technique, spray pyrolysis, by saving energy and time because the samples were synthesized using air pulverization without using any oxygen sources and without any annealing requires the following: CVD room, low pressure and more time for annealing (Sahoo et al. 2019 in Phys Chem Chem Phys 21: 6198–6206). [ABSTRACT FROM AUTHOR]

Anatase TiO2 thin films with different morphology were prepared on FTO substrates by hydrothermal method. With the increasing of hydrochloric acid concentration in the precursor, TiO2 thin films gradually evolved from spherical particle films into TiO2 nanosheet array films with a large percentage of high-energy exposed (001) planes. By analyzing the evolution rule of morphology and X-ray diffraction patterns, a reasonable growth and evolution mechanism of TiO2 thin film with different morphology was proposed, and the role of hydrochloric acid was explained. In order to further improve the performance of TiO2 thin films, CdS quantum dots (QDs) sensitization was performed on different TiO2 thin films by the successive ionic layer adsorption and reaction method. The optical absorption performance and photoelectrochemical (PEC) properties of composite films were studied by ultraviolet visible absorption spectroscopy and three-electrode electrochemistry system. The optical absorption data and PEC performance data show that the properties of CdS / TiO2 composite films are better than those of pure TiO2 thin films, and the properties of nanosheet array films are obviously better than other morphologies, which illustrates the performance superiority of TiO2 nanosheet array films with large area high-energy (001) planes exposed. The excellent PEC properties also suggest that the QDs sensitized TiO2 nanosheet array films with a large percentage of high-energy surfaces have potential applications in PEC solar cells. [ABSTRACT FROM AUTHOR]

Herein, a surface-sensitive sensor was reported as an optical waveguide (OWG) gas sensor. The sensor exhibited some advantages, including simple preparation and high sensitivity. Further, it could be operated at room temperature. TiO2 and ZnFe2O4 were employed as sensitive materials to prepare a sensor with a high response to styrene gas. The TiO2–ZnFe2O4 sol was prepared by doping ZnFe2O4 via the preparation of a TiO2 thin film, and the TiO2–ZnFe2O4 sol was fixed at the surface of the tin-doped glass waveguide by the dip-pulling method. Furthermore, the optimum conditions of the sensor were studied, and the sensors that were prepared under optimum conditions were employed to detect different concentrations of styrene gases. The results demonstrated that the sensor exhibited a high response to the determination of styrene and was reusable. Moreover, it could detect styrene across the concentration range from 1,000 ppm to 100 ppb at ambient temperature. [ABSTRACT FROM AUTHOR]

A super-hydrophilic pH-sensitive electrode with a porous TiO2 thin film is proposed in this work and fabricated using the chemical etching method. In total, 30 groups of porous TiO2 thin film were obtained by immersing a Ti sheet in NaOH, with the solution concentration ranging from 0.5–4 M and the reaction time ranging from 15–240 min. SEM, XRD, XPS, and a contact angle meter were used to investigate the influence of the chemical etching parameters on the morphology, composition, and wettability of the fabricated electrodes. The chemical etching parameters were found to have a significant influence on the specific surface area and the component of the films, which strongly affected the wettability and pH sensing characteristics of the electrodes. The electrode obtained with a solution concentration of 1 M and reaction time of 120 min is the ideal product because of its excellent wettability, with a contact angle of 5.46°, and good pH sensing characteristics in pH buffer solutions. The electrode also showed good stability regarding its wettability and pH sensing properties during storage and utilization.

The ultra-hydrophobic surface on Indonesia bamboo timber has been successfully prepared using OFP (2,2,3,3,4,4,5,5-octafluoro-1-pentanol) as a modifier agent. The hydrothermal method has been used to fabricate anatase TiO2 film followed by OFP modification. Maximal water contact angle of 123ο has been obtained for the composition of 10 mL of OFP and 15 mL of 2-propanol (B-T-OFP10). XRD analysis showed the existence of pure anatase TiO2 film on bamboo timber, confirmed by EDS result. SEM image of a TiO2-coated and a typical ultra-hydrophobic bamboo timber revealed irregular aggregates of spherical TiO2 on the surface and compact ultra-hydrophobic surface, respectively. The optimum sample (B-T-OFP10) showed excellent mechanical stability, self-cleaning property, and flame retardancy compared to pure bamboo timber.

TiO2 thin films with different surface structure have been prepared from alkoxide solutions by the sol-gel method using different cationic precursors and heat treatment techniques. The effect of using titanium isopropoxide as well as titanium butoxide as a titanium source on the surface structure and photocatalytic activity of the resultant thin films was studied. Significant differences in the rate of hydrolysis and condensation reactions during the sol-gel synthesis were observed for these titanium precursors. This had a direct influence on the morphology of the as-prepared TiO2 films. Higher quality oxide coatings were obtained from titanium isopropoxide. They were characterized by a smaller grain size, improved surface roughness and uniform coverage of the glass substrate. A beneficial effect of calcination process after each sol application cycle in contrast to single step calcination after all dip-coating cycles was observed. Photocatalytic degradation tests showed that methyl orange was decolorized in the presence of all prepared TiO2 films by exposing their aqueous solutions to UV light (λ = 254 nm). The highest photocatalytic activity had the TiO2 layer produced using titanium isopropoxide. [ABSTRACT FROM AUTHOR]

The surface dynamics of TiO 2 thin films, evolving under the implantation of 50 keV Ti ions, have been investigated. The morphological evolution, as investigated with atomic force microscopy, delineates a surface smoothening by ion implantation.The nanoscale structures at surfaces also undergo a size reduction. Scaling formalism has been applied to understand this temporal and spatial dynamics by estimating the scaling exponents (α , β and γ) via Height-height correlation function (HHCF) and power spectral density (PSD) investigations. The roughness exponent α (0.5 < α < 1) indicates these ion irradiated surfaces to be of self affine nature. Also, they evolve into locally smoother surfaces with increasing fluence. Negative growth exponent (β) also delineates surface smoothening. Exponent, γ , is observed to increase from ~ 2 at lower ion fluences to 2.5 at the highest fluence. This behavior suggests that diffusion is predominantly controlling the dynamical evolution of the ion irradiated TiO 2 surfaces at the highest fluence, similar to that in the bulk case. [ABSTRACT FROM AUTHOR]

The surface modification of TiO 2 thin film with hydrophobic agents has been a good strategy for modulation properties of this versatile material, allowing it to be compatible with a wider range of applications. This is a promising approach in the developing of improved self-cleaning materials; since films prepared with this modification are expected to exhibit photocatalytic and hydrophobic properties. However, these strategies still need to be improved, seeking the design of hydrophobic and photocatalytic structures through faster and simpler procedures, using non-fluorinated polymers. This work proposed the synthesis and characterization of self-cleaning coatings, involving a polydimethylsiloxane (PDMS)/TiO 2 system. TiO 2 thin films were modified with two different types of PDMS: hydroxyl and vinyl-terminated – and prepared by two distinct routes: Route A, which involved a modified TiO 2 sol-gel process, and route B, consisting in the functionalization of TiO 2 films after their calcination. Each route was best suited for a different type of PDMS. The PDMS modification occurred by a covalent linkage, which can allow a better durability of the functionalization on TiO 2 surface. In some cases, the functionalization was heterogeneous and promoted a significant increase in surface roughness, allowing these samples to present hydrophobicity and photocatalytic activity. [ABSTRACT FROM AUTHOR]

TiO2 thin films were deposited by the energy filtrating magnetron sputtering (EFMS) technique and the traditional direct current magnetron sputtering (DMS) technique. The influence of the filtering electrode mesh number on the structure and optical properties of TiO2 thin films was investigated. The structure, surface morphology and optical properties were characterized by XRD, SEM and ellipsometric spectroscopy, respectively. Results show that the TiO2 thin films deposited by the DMS and EFMS techniques at the same deposition parameters are composed of the anatase phase exclusively. TiO2 thin films deposited at lower deposition rate by the EFMS technique have lower crystallinity, smaller particle size and smoother surface. With increasing the mesh number, the refractive index, extinction coefficient and optical band gap are larger. [ABSTRACT FROM AUTHOR]

In this study, optimisation of the photocatalytic behaviour of crystal violet (CV) by thiourea (Tu)-codoped TiO2 thin film in fixed bed photoreactor was investigated by central composite designs (CCDs). The effective variables were pH, the concentration of CV dye, flow rate and reaction time. The results of the CCD model showed a good agreement with experimental results, with R2 = 0.9680 (p < 0.0001) and maximum degradation efficiency was obtained at the optimum conditions: dye concentration 8.5 mg/L, pH 9, flow rate 6 mL/min and reaction time 80 min. Subsequently, three absorbing chemical compounds presented in the degradation reaction were obtained by using singular value decomposition (SVD) method and evolving factor analysis (EFA). Then a multivariate curve resolution with alternating least squares (MCR-ALS) was performed to achieve the concentration and spectral profiles for each component. Finally, a hard modelling method was applied to determine the kinetic constants of distinct reactions occurred in the photocatalytic degradation process. The reaction rate constants were calculated for the first and second steps as k1 = 0.08327 (SD = ±0.0015) /min and k2 = 0.045 (SD = ±0.0006)/min, respectively.

The TiO2 thin film has been applied to reduce degradation products (free fatty acid/FFA and peroxide value/PV) in used frying oil under ultraviolet (UV) light irradiation. FFA and PV are degradation products in used frying oil that can cause various diseases in human. In this study, the TiO2 thin films were made from precursor solution with concentration ratio of titanium tetraisopropoxide (TTiP) and acetylacetone (AcAc) of 1:1, 1:2, 2:1, 2:3, and 3:2. The aim of this study is to investigate the effect of concentration ratio of TTiP and AcAc on the photocatalytic activity of TiO2 thin film in reducing FFA and PV of used frying oil. The spray coating method was used to deposit precursor solution of TiO2 onto glass substrate at 450 oC. All TiO2 thin films consist of spherical-like grain with dominant structure of TiO2 rutile. The band gap energy of TiO2 thin films was in the range 3.11-3.16 eV. Concentration ratio of TTiP and AcAc of 2:3 results in TiO2 thin film with highest photocatalytic activity in reducing FFA and PV of used frying oil.

The influence of the electrode position in devices based on nanocrystalline TiO2 thin film for sensing of isopropyl alcohol has been investigated. Two types of device structure, viz. planar and vertical, with similar dimensions (length and width) were fabricated, employing Al metal electrodes. Both sensors were tested in the concentration range from 20 ppm to 400 ppm in the temperature range of 50°C to 200°C. The comparative study revealed that both sensors (planar and vertical) exhibited an optimum operating temperature of 150°C, with an optimum response of 77% and 33.08%, respectively. The response time and recovery time were found to be faster for the vertical device compared with its planar counterpart. The dissimilar sensor response of the planar and vertical devices can be understood based on the surface states and interface kinetics of the TiO2 sensing layer. An electrical model describing the modulation of the barrier height, the effect of grain boundaries (GBs), and carrier trapping at interface states at GBs was applied to understand the response time and recovery time. [ABSTRACT FROM AUTHOR]

An enhancement in the wettability and wear resistance of titanium dioxide (TiO 2) thin films was obtained by combining a polydopamine (PDA) adhesive layer between TiO 2 layer and glass substrate. The coating layers of TiO 2 thin film, prepared from sol-gel precursor, were deposited on PDA precoated glass substrate by sol-gel dip coating technique. The wettability of films was evaluated by testing the water contact angle and adhesion force between an atomic force microscope (AFM) tip and film surface. The results indicate that the hybrid TiO 2 /PDA thin films, compared to pure TiO 2 thin films, exhibit higher wettability. UV–visible absorption spectra showed the wider absorption range in TiO 2 /PDA thin films, which means more oxygen vacancies may be induced by light irradiation and are favorable for the absorption of water molecules, thus enhancing the hydrophilicity of the films. The wear resistance and indentation tests were performed by scratching the film surface with the AFM probe and a NHT nanoindentor, respectively, indicating that the hybrid TiO 2 /PDA thin films have more wear resistance than the pure TiO 2 thin films, due to the formation of a mixed layer consisting of TiO 2 and PDA that increases the adhesive force of TiO 2 layer to the substrate. • Hybrid TiO 2 /PDA thin films were prepared by sol-gel dip coating technology. • Water contact angle of TiO 2 /PDA thin films decreased compared with pure TiO 2 films. • TiO 2 /PDA thin films have more wear resistance than pure TiO 2 thin films. • Enhancement in the wettability and wear resistance is ascribed to the PDA layer. [ABSTRACT FROM AUTHOR]

Cu 2 O nanoparticles decorated TiO 2 thin films were fabricated by laser ablation. The effects of Cu 2 O nanoparticles on the structure, optical properties and photocatalytic performance of TiO 2 thin film were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectrometer system, optical absorption and photocatalytic evaluation system, respectively. XRD patterns indicate that the decoration has the effect of lowering the grain orientation of Cu 2 O. The photocatalytic performance in hydrogen generation of Cu 2 O decorated TiO 2 composite thin film was significantly improved compared with that of either Cu 2 O nanoparticles or TiO 2 single layer thin film with 1.70 and 1.77 times, respectively. The oxidation of Cu 2 O was demonstrated to dominate the photocatalytic performances of Cu 2 O/TiO 2 composite thin films by varying the laser ablation powers. • The photocatalytic activity of TiO 2 thin films was enhanced by the decoration of Cu 2 O nanoparticles with laser ablation. • The Cu 2 O ratio dominates the photocatalytic performances of Cu 2 O/TiO 2 composite thin films. • The porous structure of Cu 2 O and the heterojunction between Cu 2 O and TiO 2 contributed to enhance photocatalytic performance. [ABSTRACT FROM AUTHOR]

TiO 2 was widely considered as a promising material for gas sensing. However, developing TiO 2 based O 2 sensors working at room temperature is still challenging owing to the difficulties of desorbing oxygen adatoms from the TiO 2 surface. Here, the influence of the UV irradiation on the desorption of the surface oxygen on the TiO 2 films was investigated by using the atmosphere dependent electric transport, Kelvin probe microscopy and x-ray photoelectron spectroscopy. A lasting high conductivity and high Fermi level of the TiO 2 film were observed after the UV irradiation in vacuum, which can be drastically suppressed by a subsequent O 2 gas exposure. Thus the UV induced desorption of the surface oxygen is evidenced. Moreover a surface charge transfer model is proposed based on DFT calculations to account for the photodesorption mechanism. Utilizing such effect, the film conductivity was increased and the adsorption sites were actively recovered upon UV irradiation, thereby greatly enhanced the O 2 gas sensitivity. Our findings provided a way to optimize the performance of the O 2 sensors at room temperature with low cost and high efficiency. • TiO 2 based Chemiresistive O 2 sensor working at room was fabricated. • The conductivity and Fermi level response to the O 2 and UV was studied. • The UV induced desorption of the oxygen adatoms on TiO 2 was evidenced. • The photodesorption mechanism was clarified by the hole transfer model. • The enhancement of the sensitivity by UV irradiation was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract In this research, TiO 2 thin films were deposited on glass substrate by chemical vapor deposition using tetra isopropylorthotitanate as a precursor at low temperature. The TiO 2 thin films were formed without using an oxygen source or annealing. Effects of substrate temperature and amount of the precursor on surface microstructure and optical properties of deposited TiO 2 thin films were investigated. X-ray diffraction (XRD), UV-visible spectrophotometry and atomic force microscopy (AFM) were used to analyze the fabricated layers. The XRD analysis revealed that structure of all prepared layers was in amorphous phase. Analysis of AFM images showed that by increasing substrate temperature, the layer surfaces became rougher and simultaneously nanoparticle size was more uniform. Texture analysis revealed that increasing substrate temperature and decreasing precursor amount both increased surface isotropy. Thickness of layers was calculated by applying the Swanepoel method to the transmittance spectra. Variations in optical parameters were studied, including of optical band gap, refractive index, extinction coefficient, complex dielectric function, Urbach energy, single oscillator energy and dispersion energy. The results indicated that optical properties were functions of substrate temperature and precursor amount. Highlights • The amorphous TiO 2 thin films were prepared by CVD method at low temperature. • Substrate temperature and precursor affected optical properties of layers. • Substrate temperature and precursor affected microstructure of layers. • The optical band gap and thickness decreased with increasing substrate temperature. • Self-similarity of surface layers increased with substrate temperature. [ABSTRACT FROM AUTHOR]

Nanostructured TiO2 films were deposited onto Indium Tin Oxide (ITO) and glass substrates by dc reactive magnetron sputtering at different substrate inclination angles. The structural and optical properties of the deposited films were studied by X-ray diffraction, scanning electron microscopy and UV–Vis spectrophotometer, respectively. Dye-sensitized solar cells (DSSC) were assembled using these TiO2 films as photoelectrodes and the effect of the substrate inclination angle in the preparing process of TiO2 films on the DSSC conversion efficiency was studied.