Titanium Dioxide Thin Films Research Articles

(3-Aminopropyl)trimethoxysilane-Functionalized Titanium Dioxide Thin-Film Nanocomposite Membrane: Enhanced Rejection Performance for Unary and Binary High-Salt Wastewater

(3-Aminopropyl)trimethoxysilane-Functionalized Titanium Dioxide Thin-Film Nanocomposite Membrane: Enhanced Rejection Performance for Unary and Binary High-Salt Wastewater

Effect of Nickel doping on the Structural, Optical, and electrical properties of titanium dioxide thin films for the application of sensing devices

Thin films of pristine titanium dioxide (TiO2) and doped with different concentrations (0–8) at.% of nickel (Ni) were synthesized onto transparent glass substrates using the spray pyrolysis deposition technique. Field emission scanning electron microscopy revealed the porous and agglomerated surface morphology of the films. X-ray diffractometer demonstrated the anatase crystal structure with a nominal increment of (101) peak. The shifting of peak position revealed the expansion of the unit cell volume from 134.64 to 137.54 (Å)3 whereas crystallite size increased from 34 to 63 nm. Using the Fizeau fringes technique, the thickness of the films was determined between 165 and 190 nm. UV–Vis measurements were employed to examine the optical characteristics of the films. The red shift was observed for 2 at.% Ni content (3.38 eV) while the blue shift was observed for (4–8) at.% Ni content. The wavelength-dependent refractive index and dielectric constant showed anomalous dispersion in the absorption band, representing the transparency of the films. The 4-point probe measurement showed a decreasing trend of resistivity with increasing temperature, whereas the resistivity increased with Ni content. Activation energy indicated a higher amount of adsorbed oxygen in the films due to the high amount of Ni content.

Improving the photoresponse of magnetron sputtered titania films by optimizing substrate and electrode configuration

Titania (TiO2) is a natural choice for photocatalysts and photodetectors due to its superior properties such as high stability and high photoelectric effect coupled with low cost fabrication routes. In this work we study the effect of substrate on the structural, morphological, and photoresponse behavior of sputtered titania thin films. We also compare the difference in photoresponse between parallel and series electrode configurations to understand the role of configuration on the design of photodetectors. TiO2 films of 50 nm thickness are sputtered onto three different substrates, namely quartz, fluorine-doped tin oxide (FTO), and silicon (Si) using direct current reactive magnetron sputtering. The structural and optical properties, along with photoresponse behavior, on these three different substrates are investigated. The sputtered TiO2 film crystallizes in the rutile structure with a uniform grain size distribution. Analysis of the transmittance data from UV–Vis spectra was used to derive the optical constants for the film. The sensitivity of TiO2 to photoresponse is highly dependent on the substrate. The response is better for Si substrate, when compared to FTO or quartz and this is due to the heterojunction formation at the TiO2/Si interface. Sensitivity, responsivity, and detectivity are also obtained for both parallel and series electrode configuration for Si substrate and better photoresponse is exhibited by the parallel configuration since carrier recombination in the bulk of the Si wafer is avoided. The photocurrent values in this work are an order of magnitude better than previous work on TiO2/Si, while the slightly slower response times maybe attributed to the strain-induced barrier reduction and band bending. Thus, this work showcases the tailoring of optoelectronic devices based on magnetron sputtered titania thin films by choosing appropriate substrates and electrode geometries.

A comprehensive analysis of environmental factors affecting solar cells: Dust accumulation, ambient temperature, and humidity

This paper aims to investigate the impact of environmental factors on solar cells, focusing on dust accumulation, ambient temperature, and humidity. The utilization of solar cells as a renewable source of energy has garnered significant attention in recent years, with three main types of solar cells: silicon-based, thin-film, and calcium titanium ore solar cells. While each type possesses unique strengths and weaknesses, understanding the impact of environmental factors is essential for monitoring quality and assessing their performance. Dust accumulation on photovoltaic (PV) panels reduces output power by blocking solar radiation transmission, causing uneven shading and reducing heat dissipation. High temperatures also negatively impact PV system operation by reducing the operating voltage of the cells, while humidity can block or diffract sunlight, reducing the output power of the system. This paper provides an analysis of existing literature and empirical studies, aiming to provide valuable insights into improving the efficiency and durability of solar cells and contributing to the widespread adoption of this renewable energy source.

Development of direct current magnetron sputtered TiO[formula omitted] thin films as buffer layers for copper indium gallium diselenide based solar cells

We describe the development and characterization of direct current magnetron sputtered titanium dioxide thin films from ceramic targets mixed with metallic titanium particles. The aim of this article is to assess their suitability for the application as buffer layer in copper indium gallium diselenide (CIGSe) based solar cells. The absorber material is produced in a semi-industrial, roll-to-roll hybrid sputter co-evaporation process. A potential strategy to modify electro-optical properties of TiO2 thin films by controlling the concentration of defects, such as oxygen vacancies, is investigated by X-ray photoelectron spectroscopy (XPS), transmission/reflection spectroscopy, spectroscopic ellipsometry, and cathodoluminescence. The presence of oxygen in the plasma during the sputter deposition process has a crucial impact on the electron transport mechanism in the studied devices. The source of the changed device characteristic can be found in modified band discontinuities at the absorber–buffer interface and in an oxidized CIGSe surface, indicated by the presence of cationic selenium, as detected by XPS. We sketch a tentative band alignment diagram and outline the range of possible modifications. The harmful effect of oxygen in the plasma forces the omission of oxygen in the process and restricts the possibilities to modify the material properties of the TiO2 layers, and consequently the prospects for an application on CIGSe. Nevertheless, the results of this work depict the principal eligibility, albeit optimization on both sides of the absorber–buffer interface are inevitable for an improved cell performance.

Reactively-sputtered super-hydrophilic ultra-thin titania films deposited at 120 °C

Abstract We investigate super-hydrophilic TiO2 (titania) films for concentrated solar-thermal power applications. Reactive magnetron sputtering has been used to deposit 8 to 12 nm thick titania thin films onto borosilicate microscope glass slides, low-Fe extra-clear architectural glass, or Si(100) wafers with a 500 nm thick thermal SiO2 layer. The effects of deposition temperature and O2 fraction of the O2/Ar working gas were investigated. We demonstrate the importance of the O2 fraction for obtaining optically transparent, super-hydrophilic (contact angle below 1°) thin films. In particular, we show that as the O2 fraction increases, contact angle decreases, obtaining super-hydrophilic titania thin films at deposition temperatures as low as 120 °C. Our work enables to develop low thermal budget cost-efficient industrial synthesis processes, paving the way for commercial applications.

Spectroscopic and computational study of the chemical reduction of [Co(dpgH)2Cl(INA)] on the surface of the nanocrystalline titanium dioxide

The Cobaloxime [Co(dpgH)2Cl(INA)], where dpgH represents diphenylglyoximato and INA stands for isonicotinic acid, was synthesized. The electrochemical behavior was studied using cyclic voltammetry, revealing a cathodic wave at −0.46 V (Co(III)/Co(II)), an anodic wave at +0.20 V (Co(II)/Co(III)), and a reversible curve at −0.83 V vs Ag/AgCl, attributed to the Co(II)/Co(I) transition.The presence of a carboxylic acid group in cobaloxime allows anchoring of the complex to nanocrystalline titanium dioxide thin films. The adsorption equilibrium was investigated using the Langmuir isotherm, yielding a Kad value of 4.7 × 104 M−1.Furthermore, upon addition of NaBH4 to a TiO2 film sensitized with cobaloxime, new bands appeared in the visible spectrum at 450 and 700 nm. The origin of these bands was investigated through theoretical calculations at the DFT/B3LYP/6-311G+(d) level of theory, which can be described as metal-to-ligand charge transfer.

Effect of precursor solution molarity on electrical and optical properties of spin-coated titanium dioxide (TiO2) thin films

Effect of precursor solution molarity on electrical and optical properties of spin-coated titanium dioxide (TiO2) thin films

Simulation and fabrication of titanium dioxide thin films for supercapacitor electrode applications

Nanostructured thin-film electrode materials are proposed for supercapacitors due to their outstanding performance over bulk materials. In this work, we fabricated a TiO2 nanotube film over a titanium foil using a top-down approach for supercapacitor electrodes. We noticed that the fabricated nanotubes are uniform and well aligned, confirmed by FESEM; the TiO2 nanotube parameters were further simulated using COMSOL Multiphysics. Simulations show an areal capacitance of 1.19393 pF/cm2 with oxidation and reduction peak currents of 6.18921×10[Formula: see text] A and −6.0320×10[Formula: see text] A, respectively, at 10 mV/s scan rate. The as-prepared nanotubes show a poor areal capacitance of 1.0193 F/cm2, which is improved to 12.8764 F/cm2 at a scan rate of 10 mV/s, that is approximately 12.63 times with oxidation and reduction peak currents of 0.129 mA/cm2 and −0.105 mA/cm2, respectively, by performing an electrochemical etching. Further, the surface roughness of both as-prepared and etched samples is studied to comment on their surface area changes. The effect of the etched sample is studied, compared and validated with simulation, which reveals that the etched TiO2 nanotubes thin-film sample shows considerable similarity with the simulation results.

Ecofriendly alkali metal cations diffusion improves fabrication of mixed-phase titania polymorphs on fixed substrate by chemical vapor deposition (CVD) for photocatalytic degradation of azo dye

Controlling the nanoscale synthesis of semiconductor TiO2 on a fixed substrate has fascinated the curiosity of academics for decades. Synthesis development is required to give an easy-to-control technique and parameters for TiO2 manufacture, leading to advancements in prospective applications such as photocatalysts. This study, mixed-phase TiO2(B)/other titania thin films were synthesized on a fused quartz substrate utilizing a modified Chemical vapor depodition involving alkali-metal ions (Li+, Na+, and K+) solution pre-treatment. It was discovered that different cations promote dramatically varied phases and compositions of thin films. The films had a columnar structure with agglomerated irregular-shaped particles with a mean thickness of 800–2000 nm. Na+ ions can promote TiO2(B) more effectively than K+ ions, however Li+ ions cannot synthesize TiO2(B). The amounts of TiO2(B) in thin films increase with increasing alkali metal (K+ and Na+) concentration. According to experimental and DFT calculations, the hypothesized TiO2(B) production mechanism happened via the meta-stable intermediate alkaline titanate transformation caused by alkali-metal ion diffusion. The mixed phase of TiO2(B) and anatase TiO2 on the fixed substrate (1 × 1 cm2) obtained from Na+ pre-treated procedures showed significant photocatalytic activity for the degradation of methylene blue. K2Ti6O12, Li2TiO3, Rutile TiO2, and Brookite TiO2 phase formations produced by K+ and Li + pretreatment are low activity photocatalysts. Photocatalytic activities were more prevalent in NaOH pre-treated samples (59.1% dye degradation) than in LiOH and KOH pre-treated samples (49.6% and 34.2%, respectively). This revealed that our developed CVD might generate good photocatalytic thin films of mixed-phase TiO2(B)/anatase TiO2 on any substrate, accelerating progress in future applications.

Supported MOCVD TiO2 Thin Films Grown on Modified Stainless Steel Mesh for Sensing Applications.

Among semiconductor metal oxides, that are an important class of sensing materials, titanium dioxide (TiO2) thin films are widely employed as sensors because of their high chemical and mechanical stability in harsh environments, non-toxicity, eco-compatibility, and photocatalytic properties. TiO2-based chemical oxygen demand (COD) sensors exploit the photocatalytic properties of TiO2 in inducing the oxidation of organic compounds to CO2. In this work, we discuss nanostructured TiO2 thin films grown via low-pressure metal organic chemical vapor deposition (MOCVD) on metallic AISI 316 mesh. To increase the surface sensing area, different inorganic acid-based chemical etching protocols have been developed, determining the optimal experimental conditions for adequate substrate roughness. Both chemically etched pristine meshes and the MOCVD-coated ones have been studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) microanalysis, and X-ray photoelectron spectroscopy (XPS). We demonstrate that etching by HCl/H2SO4 at 55 °C provides the most suitable surface morphology. To investigate the behavior of the developed high surface area TiO2 thin films as COD sensors, photocatalytic degradation of functional model pollutants based on ISO 10678:2010 has been tested, showing for the best performing acid-etched mesh coated with polycrystalline TiO2 an increase of 60% in activity, and degrading 66 µmol of MB per square meter per hour.

Effect of Deposition Layer of Titanium Dioxide (TIO2) Thin Film as Photoanode For Economically Sustainable Dye-Sensitized Solar Cell (DSSC) Application

Effect of Deposition Layer of Titanium Dioxide (TIO2) Thin Film as Photoanode For Economically Sustainable Dye-Sensitized Solar Cell (DSSC) Application

Field tests of a self-sintering, anti-soiling, self-cleaning, nanoporous metal oxide, transparent thin film coating for solar photovoltaic modules

Nanoporous metal oxide ceramic coatings, deposited using sol-gel techniques, have the potential to impart self-sintering and self-cleaning coatings to silicon oxide glass. When used on solar photovoltaic modules, these coatings can impart anti-static properties, improve wetting behavior, and degrade soiling deposits through photocatalytic activity. This paper reports on a field trial of a mixed silicon and titanium oxide thin film coating conducted in the upper midwestern U.S. Coated modules demonstrated increased electrical generation relative to uncoated controls. The results are encouraging for the commercialization of this coating technology, and provide a strong motivation for further research and development efforts.

Biological properties of surface modified 316 LVM steel

This paper aimed to investigate the selected physicochemical and biological properties of titanium dioxide thin films deposited by atomic layer deposition on 316LVM stainless steel dedicated for cardiovascular implants. The main challenge in surface modification of these implants is the complexity of the processes taking place in the circulatory system. The atomic layer deposition was carried out for a number of cycles 500 and temperature 200 °C for 316LVM stainless steel substrate. The surface topography and surface microstructure were examined. Mouse fibroblasts L929 and Human Dermal Fibroblasts (NHDF-Ad) were used for cytotoxicity assays. The following biocompatibility aspects were investigated in vitro: direct cytotoxicity, hemolysis, platelet activation and aggregation, and pro-inflammatory cytokine levels. The titanium dioxide thin films inherited the substrate topography. The surface microstructure was amorphous with the typical layer by layer growth. The film improved the in vitro cell response in terms of cell viability. The cells were also able to proliferate and adhere; however, differences in the cell morphology and the distribution of cell nuclei were observed. The host cell damage was not noted in terms of lactate dehydrogenase levels. The proposed surface modification reduced the hemolysis index and did not significantly affect platelet activation and aggregation. Acute cytotoxicity of the thin films is not predicted basing on the in vitro pro-inflammatory cytokine assay. The results of the biological tests may be basis for further biological assessment proving the full biocompatibility of the proposed surface modification dedicated for specific cardiovascular implants.

Optimization of the Geometrical Design for an All-Dielectric Metasurface Sensor with a High Refractive-Index Response

This study aims to develop a refractive-index sensor operating in the visible region using an all-dielectric metasurface, which was chosen for its advantages of low optical loss and narrow spectral bandwidth, compared to those of conventional metallic metasurfaces. COMSOL software was utilized as a calculation tool to simulate the resonant properties of an all-dielectric metasurface composed of a circular nanohole-structured titanium oxide (TiO2) thin film, with the aim of enhancing the sensitivity of the refractive index for sensing targets. The simulation focused on finding the best geometrical conditions for the all-dielectric metasurface to achieve high sensitivity. Two resonance modes observed in this metasurface were considered: the quasi-bound-state-in-the-continuum (qBIC) mode and the perfect-reflection (PR) mode. The simulated results demonstrated that high sensitivities of 257 nm/RIU at the PR mode and 94 nm/RIU at the qBIC mode in the visible spectral range could be obtained by periodically constructing the metasurface with a unit cell having a lattice constant of 350 nm, a nanohole radius of 160 nm, and a nanohole depth of 250 nm. Furthermore, the study showed that the resonance mode that enabled high sensitivity was the PR mode, with a sensitivity nearly three times larger than that of the qBIC mode and the ability to reach the highest reflectance at the resonance wavelength. The optimized feature had the highest reflectance at a resonant wavelength of 570.19 nm, and although the quality factor was 25.50, these designed parameters were considered sufficient for developing a refractive index biosensor with high sensitivity and optical efficiency when operating in the visible spectral range.

Ti doped Cr2O3 thin films: Atomic layer deposition, mechanical and optical properties

Atomic layer deposition (ALD) of titanium doped chromium oxide (CTO) films on Si (100) and SiO2 substrates was studied using deposition formula of n× (CrO2Cl2 - CH3OH) + m × (TiCl4 - H2O). The CTO films contained α-Cr2O3 eskolaite phase when deposited at Ti/(Ti+Cr) atomic ratio values of 0–0.24. During the first ALD super cycle, the growth rate of the Ti-O on chromium oxide was 2.4 times higher compared to that on TiO2 and was explained by the differences of densities of oxygen atoms on the (001) plane of eskolaite compared to their density on (001) plane of anatase. At the same time only minor influence on the growth rate of chromium oxide depending on the Ti amount was detected. The hardness value of 20.5 GPa was obtained for CTO films at Ti/(Ti+Cr) atomic ratio of 0.24, higher than 14.8 and 12.2 GPa obtained for pure chromium and titanium oxide thin films, respectively. The doping of the chromium oxide with titanium increased the absorbance of the films in the wavelength range of 350 – 450 nm and decreased the band gap energy corresponding to the indirect transition from 3.0 eV for pure Cr2O3 to 2.2 eV.

Recent Advances in the Raman Investigation of Structural and Optical Properties of Graphene and Other Two-Dimensional Materials

This research work presents our recent advancements in the study of graphene and other two-dimensional (2D) materials. This review covers studies on graphene oxide (GO) thin films deposited on various substrates, including titanium and silver thin films. The analysis reveals the role of surface-enhanced Raman scattering (SERS) and the influence of film thickness and laser intensity on the observed Raman peaks. Investigations of a silver/GO/gold sandwich structure demonstrate the presence of sharp Raman modes attributed to localized surface plasmon resonances. This review also discusses the characterization of exfoliation-synthesized graphene nanoplatelet (GNPs) thin films and of single-layer graphene deposited via chemical vapor deposition (CVD). The optical properties of molybdenum disulfide (MoS2) films are also explored. The utilization of micro-Raman spectroscopy provides valuable insights into the structural and optical properties of graphene and other 2D materials. These results hold the potential to drive advancements in various applications, such as electronics, photonics, and nanocomposites.

Characterising Hydroxyapatite Deposited from Solution onto Novel Substrates: Growth Mechanism and Physical Properties.

Whilst titanium, stainless steel, and cobalt-chrome alloys are the most common materials for use in orthopaedic implant devices, there are significant advantages in moving to alternative non-metallic substrates. Substrates such as polymers may have advantageous mechanical biological properties whilst other substrates may bring unique capability. A key challenge in the use of non-metal products is producing substrates which can be modified to allow the formation of well-adhered hydroxyapatite films which promote osteointegration and have other beneficial properties. In this work, we aim to develop methodology for the growth of hydroxyapatite films on surfaces other than bulk metallic parts using a wet chemical coating process, and we provide a detailed characterisation of the coatings. In this study, hydroxyapatite is grown from saturated solutions onto thin titanium films and silicon substrates and compared to results from titanium alloy substrates. The coating process efficacy is shown to be dependent on substrate roughness, hydrophilicity, and activation. The mechanism of the hydroxyapatite growth is investigated in terms of initial attachment and morphological development using SEM and XPS analysis. XPS analysis reveals the exact chemical state of the hydroxyapatite compositional elements of Ca, P, and O. The characterisation of grown hydroxyapatite layers by XRD reveals that the hydroxyapatite forms from amorphous phases, displaying preferential crystal growth along the [002] direction, with TEM imagery confirming polycrystalline pockets amid an amorphous matrix. SEM-EDX and FTIR confirmed the presence of hydroxyapatite phases through elemental atomic weight percentages and bond assignment. All data are collated and reviewed for the different substrates. The results demonstrate that once hydroxyapatite seeds, it crystallises in the same manner as bulk titanium whether that be on a titanium or silicon substrate. These data suggest that a range of substrates may be coated using this facile hydroxyapatite deposition technique, just broadening the choice of substrate for a particular function.

Features of Structuring and Ablation of Thin Titanium Films by Femtosecond Laser Pulses

Features of Structuring and Ablation of Thin Titanium Films by Femtosecond Laser Pulses

Colloidal TiO2 Nanorod Films Deposited Using the MAPLE Technique: Role of the Organic Capping and Absence of Characteristic Surface Patterns

Thin films of titanium dioxide (TiO2) nanocrystals, widely acknowledged for their unique physical-chemical properties and functionalities, are used in disparate technological fields, including photovoltaics, sensing, environmental remediation and energy storage. In this paper, the preparation of thin films consisting of anatase-phase TiO2 nanorods deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique and their characterization in terms of morphology, elemental composition and wettability are presented and discussed. Particular attention is paid to the effects of the laser fluence, varied over a broad range (F = 25, 50, 100 mJ/cm2), and to the role of the capping surfactants bound to the surface of the nanorod precursors. Whereas increasing fluence favored a partial removal of the surface-bound surfactants, a post-growth UV-light-driven photocatalytic treatment of the films was found to be necessary to reduce the incorporated fraction of organics to a further substantial extent. It was noteworthy that, under our experimental conditions, the distinctive surface patterns and roughness that commonly degrade the morphology of films deposited using the MAPLE technique were not observable. This previously unreported experimental evidence was rationalized on the basis of the interaction dynamics between solvent/solute droplets ejected from the laser-irradiated target and the rough surfaces of the growing film.