TiO2 Phase Research Articles

Tweaking the structural, micro–structural, optical and dielectric properties of anatase titanium dioxide via doping of nitrogen ions

The pure nanostructured anatase titanium dioxide (TiO2) and subsequent nitrogen–doped derivatives (TiO2–xNx; where, x = 0.005, 0.01, 0.05) were synthesized by sol–gel auto–combustion technique. XRD analysis confirms the formation of pure anatase phase of TiO2 up to doping of 1 mol% (x = 0.01) of nitrogen having tetragonal structure with space group of I41/amd whereas an additional monoclinic phase of TiO2–B was observed at 5 mol% of nitrogen doping in TiO2. This sample has smallest crystallite size of ∼4.7 ± 0.2 nm corresponding to TiO2–B phase and ∼12.0 ± 0.1 nm corresponding to anatase phase. XRD also reveals that the crystallite size of all other samples having pure anatase phase ranges between ∼8.7 ± 0.1 nm & 13.9 ± 0.1 nm. The crystalline phase revealed from XRD of all samples was further supported by the Raman analysis. The direct optical band gap of pure TiO2 (∼3.4 eV) was reduced non–monotonically after nitrogen doping in the ranges from ∼2.8 eV (TiO1.95N0.05) to ∼2.0 eV (TiO1.99N0.01). FTIR spectra confirm the metal oxide bond formation, surface adsorption of water molecules and presence of residual hydroxyl group in all crystalline samples. HRTEM analysis validates the coexistence of secondary phase of TiO2–B along with anatase phase of TiO2 in studied highest doped sample (TiO1.95N0.05) including its broader particle size distribution as compared to pure TiO2. The electrical studies reveal that the highest values of dielectric constant and ac conductivity can be realized for pure TiO2 and at 1 mol% (x = 0.01) of nitrogen doping, among all the studied nitrogen doped samples.

Insight into the Structural and Performance Correlation of Photocatalytic TiO2/Cu Composite Films Prepared by Magnetron Sputtering Method

Photocatalysis technology, as an efficient and safe environmentally friendly purification technique, has garnered significant attention and interest. Traditional TiO2 photocatalytic materials still face limitations in practical applications, hindering their widespread adoption. The research prepared TiO2/Cu films with different Cu contents using a magnetron sputtering multi-target co-deposition technique. The incorporation of Cu significantly enhances the antibacterial properties and visible light response of the films. The effects of different Cu contents on the microstructure, surface morphology, wettability, antibacterial properties, and visible light response of the films were investigated using an X-ray diffractometer, X-ray photoelectron spectrometer, field emission scanning electron microscope, confocal laser scanning microscope, Ultraviolet–visible spectrophotometer, and contact angle goniometer. The results showed that the prepared TiO2/Cu films were mainly composed of the rutile TiO2 phase and face-center cubic Cu phase. The introduction of Cu affected the crystal orientation of TiO2 and refined the grain size of the films. With the increase in Cu content, the surface roughness of the films first decreased and then increased. The water contact angle of the films first increased and then decreased, and the film exhibited optimal hydrophobicity when the Cu target power was 10 W. The TiO2/Cu films showed good antibacterial properties against Escherichia coli and Staphylococcus aureus. The introduction of Cu shifted the absorption edge of the films to the red region, significantly narrowed the band gap width to 2.5 eV, and broadened the light response range of the films to the visible light region.

Exploring changes in structural, electronic and elastic properties of TiO2 under pressure: A DFT investigation

Titanium dioxide (TiO2) is a semiconductor material that widely used in numerous applications due to its exceptional physical and chemical properties. This study explores the structural, electronic and elastic properties of TiO2 phases in rutile, anatase and brookite under hydrostatic pressure up to 100 GPa. At 0 GPa, the computed lattice parameters and volumes align closely with experimental data. The band structure reveals that rutile and brookite exhibit direct band gaps while anatase shows an indirect band gap. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Cauchy pressure, Pugh ratio and Poisson’s ratio were calculated using the Voigt-Reuss-Hill approximation. Our findings confirm the mechanical stability of all TiO2 phases and offer insights that align with existing theoretical and experimental data. These findings provide a comprehensive understanding of behavior of TiO2 under high-pressure condition which is crucial for optimizing its applications in various fields such as photocatalysis and solar cells.

The Fate of “Immobile” Ti in Hyaloclastites: An Evidence from Silica–Iron-Rich Sedimentary Rocks of the Urals Paleozoic Massive Sulfide Deposits

The formation of Paleozoic silica–iron-rich sedimentary rocks in the Urals volcanic-hosted massive sulfide (VHMS) deposits is considered a result of seafloor alteration of hyaloclastites mixed with calcareous/organic or sulfide material. These rocks host various Ti mineral phases pointing to the transformation of precursor metacolloidal TiO2 phases to disordered anatase during seafloor alteration of hyaloclastites, which was later converted to globules and clusters and further to diagenetic rutile. The LA-ICP-MS analysis showed that the Ti content of hyaloclasts partly replaced by finely dispersed Si–Fe aggregates increases to 540–2950 ppm and decreases (<5 ppm) in full Si–Fe pseudomorphs after hyaloclasts. LA-ICP-MS element mapping reveals the enrichment in V, U, Cr, W, Nb, Pb, and Th of the anatase globules and the local accumulation of Zr, Y, and REE on their periphery. Corrosive biogenic textures in the outer zones of some hyaloclasts and biomorphic aggregates in rocks contain anatase particles in assemblage with apatite indicating the biophilic properties of Ti. This work fills the knowledge gaps about Ti mobilization during low-temperature seafloor alteration of hyaloclastites in VHMS deposits.

Precisely regulated crystalline phase of TiO2@composite G doped with Al3+: For the preparation of highly conductive, corrosion resistant conductive coatings

The development of conductive materials is crucial to the upgrading of modern science and technology industries. In recent years, the research on conductive materials synthesized based on TiO2 has mainly focused on improving the conductivity and stability of the materials. And this study, based on the high conductivity of the material, innovatively proposes a method to precisely regulate the crystal phase and morphology of TiO2 by CH3COOH and temperature together. Meanwhile, the heterostructure was successfully built by doping Al3+ into the TiO2 lattice, and a new conductive pathway (Al-O-C) was constructed. Finally, the composite G was prepared as an Al3+-doped TiO2 composite G (Al-T/G) functional material, and it was verified by first-principles calculations (DFT). The experimental results show that the Al-T/G material not only has the low surface resistance and high whiteness of TiO2, but also is endowed with more excellent resistivity (0.203 Ω·cm) and protection efficiency (92.45 %). Meanwhile, compared with the conventional antimony-doped tin dioxide (ATO) conductive materials, the Al-T/G functional materials prepared in this paper are basically harmless to the environment in the experimental process while ensuring high conductivity. Most importantly, this paper explores the bonding mechanism of Al3+-doped TiO2 conductive materials, which provides new insights and ideas in the field of dopant-modified TiO2 conductive materials.

Confined interfacial self-assembly of graphene-like carbon/MXene composite electrodes for capacitive deionization

Electrodes that have high desalting capacity, fast desalting rates and stable desalination performance are needed in capacitive deionization (CDI) technologies for water security. Herein, confined interfacial self-assembly of lignin-based graphene-like carbon (GC) precursors in Ti3C2-MXene interlayers was developed for forming GC/MXene composites. The formation of GC was generated in-situ by KHCO3-assisted pyrolytic carbonization which leads to exfoliation of multilayered MXene thereby forming GC/MXene heterostructures having strong interfacial interactions. GC/MXene exhibited tremella-like nanosheets morphology, accompanied by the formation of a TiO2 phase at the interface of GC and MXene hybridization, which confirmed formation of a heterostructure. Crystallographic phase identification of GC/MXene showed the exfoliation of MXene. GC/MXene had an ultra-negative surface charge of −39.3 mV, making it favorable for application as a cathode for Na+ removal. The GC/MXene heterostructure had high desalting capacity (54.2 mg g−1), high desalting rate (2.7 mg g−1 min−1), and stable cycling performance (90 % SAC retention after 30 cycles). The interfacial self-assembly strategy developed in this work is expected to enable green synthesis routes for graphene/MXene-based composite materials that allow construction of 2D/2D heterostructures for multilayer MXene and their analogues.

Anisotropic ferroelectric-shaped hysteresis loop and colossal permittivity in thermally treated rutile TiO2 single crystals

Space charge polarization is an unavoidable phenomenon in electronic components that leads to deterioration of electrical response. Hence manipulation and utilization of space charge polarization to improve electrical properties is a phenomenal task. In the present study, heating treatment produces oxygen vacancies, resulting in the crystal structures (i.e., modulated structure and intergrowth structure) and band gap are anisotropic, which in turn leads to anisotropic nonlinear polarization behavior and colossal permittivity. Quantitative analysis of the atomic-scale structure confirms the modulated structure and intergrowth structure are anisotropic. A modulated structure along a axis of rutile TiO2 with a width of six times that of a rutile crystal cell a is constructed through an intergrowth structure between rutile and srilankite TiO2 phases in rutile TiO2 single crystals, wherein space charges at the intergrowth structure give rise to ferroelectric-shaped hysteresis in heated TiO2 single crystals along [001] direction. Impedance spectra display three kinds of space charge polarizations (modulated structure, intergrowth structure, and electrode non-ohmic contact) contribute to the colossal permittivity along [001] direction. The space charge polarizations contribute to a colossal permittivity (∼45,000), high resistivity (∼1010 Ω cm), and ferroelectric-shaped P-E loop (remanent polarization: ∼17.1 μC/cm2, coercive field: ∼4.3 kV/cm) in the heated TiO2 single crystal along [001] direction, while a linear polarization behavior and permittivity value of 120 are obtained along [100] direction. The findings provide guidance for the utilization of space charge polarization in dielectric materials.

Influence of TiO2 Phases and Operational Parameters on Photocatalytic Degradation of Methyl Orange

Influence of TiO2 Phases and Operational Parameters on Photocatalytic Degradation of Methyl Orange

Integrating machine learning with experimental investigation for optimizing photocatalytic degradation of Rhodamine B using neodymium-doped titanium dioxide: a comprehensive approach with toxicity assessment.

In this study, neodymium-doped titanium dioxide (Nd-TiO2) nanoparticles were synthesized via a hydrothermal method for the photocatalytic degradation of Rhodamine B (RhB) under UV and sunlight conditions. The properties of these NPs were comprehensively characterized. And optimization of RhB degradation was conducted using control-variable experiment and artificial neural networks (ANN) under various operational conditions and in the presence of competing compounds. The acute toxicity of both NPs, RhB, and the environmental impact of the photocatalytic treatment effluent on Danio rerio were evaluated. The Nd modification increased the catalyst's specific surface area and thermal stability. X-ray diffraction confirmed the tetragonal anatase phase in undoped TiO2, while Nd-doped TiO2 exhibited shifts in peaks and the presence of brookite and rutile phases. Nd (1mol%) doped TiO2 demonstrated superior RhB photocatalytic degradation efficiency, achieving 95% degradation and 82% total organic carbon (TOC) removal within 60min under UV irradiation. Optimization under sunlight conditions yielded 95.14% RhB removal with 0.28g/L photocatalyst and 1% doping. Under UV light, 98.12% RhB removal was optimized with 0.97% doping, along with the presence of humic acid and CaCl2. ANN modeling achieved high precision (R2 of 0.99) in modeling environmental photocatalysis. Toxicity assessments indicated that the 96-h LC50 values were 681.59mg L-1 for both NPs, and 23.02mg L-1 for RhB. The treated dye solution exhibited a significant decline in toxicity, emphasizing the potential of 1% Nd-TiO2 in wastewater treatment.

The encapsulation of noble metal over metal oxide semiconductor TiO2@Ag for the degradation of sulphur dye in effluent water by photocatalysis and electrochemical water splitting

Metal Oxide Semiconductor - Metal core-shell nanostructure with TiO2 as core and Ag nanoparticles as shell (TiO2@Ag) have been synthesized by a simple, environmentally friendly room temperature wet chemical method. The prepared TiO2@Ag core-shell nanoparticle was characterized by using various analytic techniques. X-ray diffraction analysis confirms the formation of tetragonal bcc structure anatase phase of TiO2 and Face-Centred Cubic structure (fcc) of silver in core-shell nanostructure. Fourier Transform Infrared Spectroscopy (FTIR) study proved the presence of characteristic peaks of both TiO2 and Ag. XPS study revealed the existence Ti4+ and metallic silver in core-shell nanostructure, High - Resolution Transmission Electron Microscopy (HR–TEM) and High - Resolution Scanning Electron Microscopy (HR–SEM) revealed the covering of Ag nanoparticles at the surface of TiO2 spheres. The TiO2@Ag core-shell nanoparticles exhibit a high residual mass of 95.9 % and stability to withstand up to 1000 °C. The prepared TiO2@Ag core-shell nanoparticles as photocatalyst showed enhanced photocatalytic degradation (240 min) of sulphur dye in effluent water with a degradation efficiency of 81 % and capable of employing in wastewater treatment to eliminate toxic elements present in it. In the current study, we have used core-shell nanoparticles prepared using the wet chemical method at room temperature. The prepared core-shell nanoparticles were used to study the photocatalytic degradation of sulphur black dye directly collected from textile effluent water. They were also used for the production of oxygen and hydrogen through the electrolysis process. The synthesized TiO2@Ag core-shell nanoparticles act as effective electrocatalyst for the production of oxygen and hydrogen through oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) using the electrolysis process.

Regulating crystal phase of TiO2 to enhance catalytic activity of Ni/TiO2 for solar-driven dry reforming of methane

Ni/TiO2 catalyst is widely employed for photo-driven DRM reaction while the influence of crystal structure of TiO2 remains unclear. In this work, the rutile/anatase ratio in supports was successfully controlled by varying the calcination temperature of anatase-TiO2. Structural characterizations revealed that a distinct TiOx coating on the Ni nanoparticles (NPs) was evident for Ni/TiO2-700 catalyst due to strong metal-support interaction. It is observed that the TiOx overlayer gradually disappeared as the ratio of rutile/anatase increased, thereby enhancing the exposure of Ni active sites. The exposed Ni sites enhanced visible light absorption and boosted the dissociation capability of CH4, which led to the much elevated catalytic activity for Ni/ TiO2-950 in which rutile dominated. Therefore, the catalytic activity of solar-driven DRM reaction was significantly influenced by the rutile/anatase ratio. Ni/TiO2-950, characterized by a predominant rutile phase, exhibited the highest DRM reactivity, with remarkable H2 and CO production rates reaching as high as 87.4 and 220.2 mmol/(g·h), respectively. These rates were approximately 257 and 130 times higher, respectively, compared to those obtained on Ni/TiO2-700 with anatase. This study suggests that the optimization of crystal structure of TiO2 support can effectively enhance the performance of photothermal DRM reaction.

Influence of Ag doping on structural, morphological, and optical characteristics of sol-gel spin-coated TiO2 thin films

Pure and Ag-doped Titanium dioxide (TiO2) thin films have been synthesized via the sol-gel spin coating method, and their structural, morphological, and optical properties have been investigated. X-ray diffraction analysis verifies that the polycrystalline anatase TiO2 phase is retained up to 2 % Ag doping. However, lattice expansion and grain refinement down to 25.345 nm are observed with increasing Ag content. Scanning electron microscopy (SEM) reveals the formation of large, isolated TiO2 aggregates separated by drying-induced cracks across the film surface. Optical studies show the undoped TiO2 films demonstrate excellent visible transparency (>75 % transmittance) that slightly decreases upon Ag doping, though it remains suitably high for device applications. Meanwhile, optical absorption and defect states improve with more Ag incorporation, narrowing the TiO2 bandgap from 3.83 eV (undoped) to 3.51 eV (2 % Ag-doping) due to the incorporation of Ag-induced electronic states just below the conduction band minimum. The capability to control optical and structural properties through Ag doping highlights the potential of these TiO2 films suitably tailored for photovoltaic devices or self-cleaning coatings.

Large dielectric properties of niobate-titanate glass ceramics prepared by powder sintering method

Niobate-titanate glass-ceramics with large dielectric constant were prepared by the dual optimization strategy employed——glass powder sintering method and simultaneous introduction of multiple nucleating agents. The study delved into the crystallization and microstructure of the glass ceramics, with a subsequent characterization of their dielectric and ferroelectric properties. In this investigation, the crystalline phase underwent a transformation from the Pb2Nb2O7 phase of G700 glass ceramics to the coexistence of (Pb, Sr)TiO3 and (Ba, Sr, Pb)Nb2O6 phase of G1100 glass ceramics. The crystal phase content exhibited a notable increase from 29 % to 82 %. The relative density of the glass ceramics reached a high of 99.4 %. The maximum dielectric constant recorded was 1493, accompanied by a maximum energy efficiency of up to 88.0 %. These results underscore the potential of glass ceramics as a promising material for Multilayer Ceramic Capacitor (MLCC) dielectric layers.

Accelerating Polysulfide Adsorption and Conversion from the Hybrid Phase of TiO2 and N-Doped Carbon toward High-Performance Li–S Batteries

Accelerating Polysulfide Adsorption and Conversion from the Hybrid Phase of TiO₂ and N-Doped Carbon toward High-Performance Li–S Batteries

Synthesis, mechanical characterization, and biocompatibility evaluation of Graphene-TiO2 reinforced alumina for biomedical applications

The study addresses the limited fracture toughness of Al2O3 ceramics by developing graphene-TiO2 reinforced alumina nanocomposites through pressing. Mechanical properties, including hardness, fracture toughness, and elasticity, were examined, alongside the structural characterization via XRD analysis and microstructure evaluation using SEM. Cytotoxicity and cell adhesion tests were conducted for in vitro biological evaluation. The inclusion of a graphene additive led to a nearly threefold increase in fracture toughness, reaching up to 8.161 MPa m1/2. Graphene doping induced a discernible shift to lower angles in the XRD pattern, revealing the presence of Al2O3, Al2TiO5, and TiO2 phases. Samples immersed in artificial body fluid for 14 days exhibited minimal ion release, with Titanium ion below 0.001 mg/L and aluminum ion below 0.05 mg/L, indicating a lack of significant ion release. The cytotoxic activity of the samples against NIH/3T3 cells was assessed through Alamar Blue analysis, revealing no significant change in cell viability after 48 h of exposure.

Effects of Nd-doping on crystal phase, structure and photocatalytic performance of TiO2 powders prepared by sol-gel method

Abstract In this work, 0.3–2 mol% neodymium (Nd) doped titanium dioxide (TiO2) powder was prepared by sol–gel method. The XRD showed that the anatase phase occur for the Nd doped TiO2 powders, and the Nd doping suppressed the original rutile phase for the pure TiO2 powder. SEM and TEM revealed that Nd doping reduced the tendency of severe aggregation and increased the specific surface area compare with pure TiO2 powder, and the Gibbs free energy difference did not reach the critical value of the phase transition driving force, while the adjustment of the Ti-O bond length caused by the addition of Nd3+ impeded the transformation of TiO2 to rutile phase. The photocatalytic activity test results for Methylene blue show that the 0.5 mol% Nd doped TiO2 had the best photocatalytic activity with the degradation efficiency of 96.2%.

Identifying the effect of photo-generated carriers on the phonons in rutile TiO2 through Raman spectroscopy

Abstract Investigating lattice vibrations through Raman spectroscopy is a crucial method for studying crystalline materials. Carriers can interact with lattices and influence lattice vibrations; thus, it is feasible to study the effect of photo-generated carriers on phonons by analyzing changes in the Raman spectra of semiconductors. Rutile is one of the predominant crystalline phases of TiO2, which is a widely utilized metal oxide semiconductor. In this work, rutile TiO2 is coated on a thinned optical fiber to concentrate ultraviolet light energy within the material, thereby enhancing the generation of carriers and amplifying the changes in the Raman spectra. A Raman detection laser with a wavelength of 532 nm is utilized to collect the Raman spectra of rutile TiO2 during irradiation. Using this setup, the impact of photo-generated carriers on the phonons corresponding to Raman vibrational modes is researched. The localization and non-radiative recombination of photo-generated carriers contribute to a reduction in both the frequencies and lifetimes of phonons. This work provides a novel approach to researching the effect of carriers on phonons.

Au–decorated TiO2 nanoparticle photoanode: synthesis, structural, optical properties and photoelectrochemical water splitting performance

This study presents a novel approach to synthesizing Au-decorated TiO2 (Au/TiO2) nanoparticles (NP) using a spin-coating method, showcasing significant advancements in photoanode development. The resulting Au/TiO2 NPs exhibit well-defined crystallite structures comprising Au and TiO2 phases, featuring Au NP sizes ranging from 2.61 nm to 6.10 nm. Notably, the energy bandgap of these Au-decorated TiO2 NPs demonstrates a discernible redshift of 3.22–3.02 eV across various Au concentrations (1%–20%). Photoluminescence spectra reveal three distinct emission peaks at room temperature in the 400–550 nm wavelength range. The water-splitting activity of the Au/TiO2 NPs is investigated through the photoelectrochemical cell (PEC) employing an electrolyte solution with 1.0 M KH2PO4/K2HPO4 buffer. The results demonstrate a substantial photocurrent density of 0.23 mA.cm–2 at a potential of 1.6 V (versus RHE) and a photoconversion efficiency of 0.1% at 0.52 V (vs. RHE), respectively. This pioneering study underscores the potential of Au/TiO2 NP photoanodes as key components in advancing sustainable energy technologies, particularly in the realm of efficient PEC water-splitting applications.

Exploring the photocatalytic efficacy of core–shell CeO2/TiO2 nanocomposite synthesized via solution combustion synthesis

Abstract This study investigates the photocatalytic efficacy of core–shell CeO2/TiO2 nanocomposite (CT-NC) synthesized via solution combustion synthesis. Various characterization techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV), photoluminescence spectroscopy (PL), Raman spectroscopy, field emission scanning electron microscopy (FESEM) along with energy-dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy with selected area electron diffraction (HRTEM-SAED) were employed to analyze the nanomaterials. XRD pattern confirmed the realization of cubic and tetragonal phases of CeO2 and TiO2. The vibrational modes observed below 800 cm−1 confirmed the metal-oxygen bonds of the synthesized samples. The energy bandgap (Eg) of CT-NC, as estimated from UV–vis spectra, reduced to 2.28 eV, resulting in a significant enhancement of the photocatalytic activity. The various emission peaks in the visible region due to the oxygen vacancies facilitated the generation of Reactive Oxygen Species (ROS). EDS analysis confirmed the presence of elements and the purity of the samples. Furthermore, CT-NC demonstrated remarkable dye degradation efficiency, achieving a maximum efficiency of 98.15 % under visible light irradiation for 120 min. This enhanced activity is attributed to the Advanced Oxidation Process (AOPs). Overall, the results highlight the potential of CT-NC as an efficient photocatalyst for environmental remediation.

Synthesis process, thermal and electrical behaviors of Ti3C2Tx MXene

AbstractSynthesis of two‐dimensional (2D) titanium carbide (Ti3C2Tx), with the name of MXene, by etching Ti3AlC2 (MAX) for different times 20 (v/v) % hydrofluoric acid (HF) at 40 °C was carried out. The influences of time, temperature and source of MAX on the synthesis of MXene were researched. The MXenes produced were characterized by fourier‐transform ınfrared (FT‐IR) spectroscopy technique, energy dispersive x‐ray spectroscopy (EDX), scanning electron microscopy (SEM), x‐ray diffraction (XRD) and thermogravimetry (TG) instruments. Above 390 °C, MXene layers were considerably oxidizing and forming anatase and rutile phases of TiO2 under air atmosphere. The resistance of MAX and MXene was 3.6 Ω and 116 Ω, respectively. However, the resistance of the residual part of MXene heated to 620 °C considerably increased to 17850 Ω. This behavior is another important piece of evidence showing that the MXene crystal structure has changed significantly and transformed into a new chemical structure containing anatase and rutil titanium oxide (TiO2). The dielectric loss (ϵ’’) and alternating conductivity (δac) of the MAX and MXenes were determined from their impedance measurements. The ϵ’’ and δac values of MXene were compared with those of MAX. Direct curent conductivities of MAX and MXene produced for 24 h were found to be 0.016 S/cm and 0.0023 S/cm, respectively.