Rutile Phase Research Articles

An Interesting Functional Phase Change Material VO2: Response to Multivariate Control and Extensive Applications in Optics and Electronics

AbstractUnder physical conditions such as TC = 68 °C, Vanadium dioxide (VO2) undergoes a reversible transformation from a monoclinic phase to a tetragonal rutile phase. This transformation is accompanied by a series of changes in physical properties, including transmittance, conductivity, and refractive index, which make it an excellent functional material. Based on this, VO2 has been extensively researched and applied in the fields of electronics and optics, yielding remarkable results and making it a hot research material. This paper reviews the phase transition mechanisms and optical/electrical properties of VO2, as well as its phase transition hysteresis. From the application perspective, this paper summarizes the modulation content under various external excitations and the element doping effects. Finally, this paper summarizes the classic VO2‐based devices, and points out the development direction and potential of VO2 in optics and electronics. This review provides a systematic summary of VO2, which is useful for its practical applications.

Structural, optical, photocatalytic, and magnetic properties of new hydrothermal synthesized Cd1–xSnxFe2O4 nanocomposites

Herein, structural, surface area, optical, photocatalytic, and magnetic properties of a new Cd1–xSnxFe2O4 nanocomposites (1 ≥ x ≥ 0), synthesized by the hydrothermal approach were investigated. The nanocomposite formation is confirmed by X-ray diffraction analysis (XRD), Transmission electron microscopes (TEM), Fourier transform infrared (FTIR), Inductively coupled plasma (ICP), and Energy dispersive X-ray (EDX) analyses. The XRD findings reveal the formation of Fe2O3 at x = 0, 0.2, 0.4, and 1, while the Fe3O4 phase at x = 1 besides the spinel CdFe2O4 phase for x = 0.6 and 0.8, and rutile SnO2 phase for x ≥ 0.8. The crystal structure, e.g., lattice parameters, bond length, cell volume, theoretical density, crystallite size, dislocation density, and microstrain are remarkably influenced by elemental ratios. The average crystallite size of composites declined to 15.2 ± 4 nm as x increased to 0.4, then grew to 40.5 ± 4 nm at x = 0.6, and then decreased to 21 ± 10 nm at x = 1. The particle morphologies were deduced, and crystal structures were confirmed by analyzing field-emission scanning electron microscope (FE-SEM), and TEM micrographs. FTIR confirmed the presence of metal oxide bands for all nanocomposites. The surface area was calculated via the Brunauer–Emmett–Teller (BET) and Barrett-Joyner-Halenda (BJH) theories to the N2 adsorption–desorption isotherm and equals 10.5, 20.3, 17.1, and 25.2 m2/g at x = 0, 0.4, 0.6, and 1, respectively. The magnetic properties of the Cd1–xSnxFe2O4 nanocomposites were studied by vibrating-sample magnetometry (VSM) technique, which displayed their ferromagnetic behaviors. The addition of Sn2+ into the composite improved the magnetic saturation from 0.42 to 34.7 emu/g by changing x from 0 to 0.4 then was reduced to 5.9 emu/g at x = 1 which well matched with the behavior of total pore volume. Furthermore, the indirect optical band gap (Egin) was increased, e.g., Egin equals 1.22, 1.82, 1.88, and 2.08 eV for x = 0, 0.4, 0.6, and 1, respectively. Methylene blue photocatalytic performance was investigated, and the maximumdegradation efficiency of 44.33 %was detected using Cd1–xSnxFe2O4 at x = 0.8 under UV–visible irradiation for 160 min.

TiCl4 precursor affecting the performance of HTM-free carbon-based perovskite solar cell

The presence of TiO2 used as an efficient electron transport layer is crucial to achieving high-performance solar cells, especially for a hole transport material (HTM)-free carbon-based perovskite solar cell (PSC). The hydrolysis of TiCl4 is one of the most widely used routes for forming TiO2 layer in solar cells, which includes the stock solution preparation from TiCl4 initial precursor and the thermal hydrolysis of the stock solution. The second thermal hydrolysis step has been extensively studied, while the initial hydrolysis reaction in the first step is not receiving sufficient attention, especially for its influence on the photovoltaic performance of HTM-free carbon-based devices. In this study, the role of TiCl4 stock solution in the growth process of TiO2 layer is examined. Based on the analysis of the Ti(IV) intermediate states for different TiCl4 concentrations from Raman spectra, 2 M TiCl4 precursor exhibits moderate nucleation and growth kinetics without generating too many intermediates which occurs in 3 M TiCl4 precursor, yielding ∼300 nm size spherical TiO2 agglomerates with a rutile phase. In the aspect of devices, the HTM-free carbon-based PSCs fabricated using 2 M TiCl4 precursor deliver a conversion efficiency beyond 17%, which may be attributed to the reduced defect in compact TiO2 layer.

Formation, Transformation, and Electrical Performance of Magnéli Phases Obtained by Flame Spraying from TiO2 Particles

In this paper, the formation and transformation of Magnéli phases (TinO2n-1) during manufacturing of flame-sprayed coatings from two powders consisting of anatase nanoparticles and submicrometric particles with Magnéli phases is analyzed, respectively. These powders were thermally sprayed on a ceramic substrate through oxidizing and neutral flame. Crystalline phases in powders and coatings were identified by x-ray diffraction and quantified by the Rietveld method, verifying the presence of identified crystalline phases in coatings by x-ray photoelectron spectroscopy. Finally, the electrical conductance of coatings was measured by the four-point probe method. Results indicate that Magnéli phases are produced from anatase nanoparticles sprayed using both the oxidizing and neutral flames, and when the neutral flame and finest particles are used, a high quantity of Ti4O7 and Ti5O9, recognized thanks to their high electrical conductivity, is obtained. In contrast, when the coatings were fabricated from the powder containing Magnéli phases, they were oxidized as much in oxidizing as in neutral flame, producing a partial transformation from Ti4O7 and Ti5O9 to both the rutile phase and TiO in low quantity. In spite of this partial transformation, the coatings maintain high electrical conductivity thanks to Ti4O7 and Ti5O9 Magnéli phases remaining and the TiO produced.

Easy and green synthesis of TiO2 (Anatase and Rutile): Estimation of crystallite size using Scherrer equation, Williamson-Hall plot, Monshi-Scherrer Model, size-strain plot, Halder- Wagner Model

TiO2 is one of the most important metal oxides which are widely applied in various fields, and the modifications of synthesis process and in-depth characterization are growing up day by day. Nano Anatase and Rutile phases of TiO2 were synthesized from titanium iso-butoxide following an easy approach where no toxic chemicals were utilized. Nano-TiO2 (Rutile phase) was synthesized from the thermal conversion of the nano-Anatase phase (which was obtained at room temperature) at 700 °C temperature for 2 h. Anatase and Rutile phases were confirmed by the X-ray diffraction (XRD) data and matched with the standard database. Different crystallographic parameters such as lattice parameters, and preference growth were calculated from the XRD data. Different methods were utilized to estimate the crystallite size of the Anatase and Rutile phase of TiO2 by using the Scherrer equation, Williamson-Hall plot, Monshi-Scherrer Model, Size-strain plot method, Halder- Wagner Model, and Sahadat-Scherrer Model. All the models presented crystallite size in the accepted region, and linear regression coefficients were also taken into consideration. In addition to the crystallite size, various intrinsic parameters such as stress, strain and energy density were also computed from the mentioned models based on XRD.

Tailoring of optical band gap in carbon-doped TiO2 nanofibers

Abstract The study intended to enhance the visible light activity of titanium dioxide (TiO2) by doping it with carbon, thereby reducing its effective band gap. Carbon-doped TiO2 nanofibers were synthesized using a simple electrospinning process. The prepared samples were then characterized to investigate their properties. X-ray diffraction (XRD) analysis confirmed the presence of the rutile phase of TiO2 in the nanofibers. The XRD pattern exhibited maximum peak intensity at the highest temperature used during synthesis, indicating that the temperature influenced the crystalline structure of the nanofibers. Scanning electron microscopy (SEM) was conducted to examine the morphology of the nanofibers. The results revealed that as temperature increased, the diameter of the nanofibers decreased. The XRF (X-ray Fluorescence) results indicate the atomic composition of carbon-doped TiO2 nanofibers. UV–vis spectroscopy was performed to evaluate the optical properties of the carbon-doped TiO2 nanofibers. The results demonstrated a shift of the optical band towards the visible region. Moreover, the carbon doping reduced the effective band gap, resulting in improved visible light activity of the TiO2 material. These results have significant implications for potential applications of carbon-doped TiO2 nanofibers in various fields, such as photocatalysis and solar energy conversion.

Revealing the role of defect-induced trap levels in sol–gel-derived TiO2 samples and the synergistic effect of a mixed phase in photocatalytic degradation of organic pollutants

Sol–gel-derived TiO2 samples were synthesized by annealing a xerogel at three different temperatures, namely 350, 550, and 750 °C, which resulted in near-pure anatase, an anatase/rutile mixed phase, and a pure rutile phase, respectively. With the increase in annealing temperature, the average crystallite size increased from ca. 9–48 nm, while the specific surface area decreased from 110.9 to 2.3 m2/g. The mixed-phase sample with a rutile-rich outer layer showed the highest photocatalytic activity, even though the specific surface area of this sample (7.4 m2/g) was much lower than that of the anatase sample (110.9 m2/g). In solar photocatalytic degradation of Methylene Blue dye, the rate constant over this sample (6.25 × 10−2 min−1) was more than three times that over the commercially available photocatalyst Degussa P25 (1.97 × 10−2 min−1). The synergistic increase in the photodegradation performance is attributed to interfacial charge transfer between the anatase and rutile phases. The photocatalytic performances of the anatase and rutile phases can be correlated to the presence of different types of defects. The majority of defects in the anatase sample are shallow levels associated with Vo+, while rutile contains shallow levels related to Ti3+ as well as deep levels corresponding to Vo++.

Boosting Polysulfide Redox Kinetics by Temperature-Induced Metal-Insulator Transition Effect of Tungsten-Doped Vanadium Dioxide for High-Temperature Lithium-Sulfur Batteries.

The practical application of Li-S batteries is still severely restricted by poor cyclic performance caused by the intrinsic polysulfides shuttle effect, which is even more severe under the high-temperature condition owing to the inevitable increase of polysulfides' solubility and diffusion rate. Herein, tungsten-doped vanadium dioxide (W-VO2) micro-flowers are employed with first-order metal-insulator phase transition (MIT) property as a robust and multifunctional modification layer to hamper the shuttle effect and simultaneously improve the thermotolerance of the common separator. Tungsten doping significantly reduces the transition temperature from 68 to 35 °C of vanadium dioxide, which renders the W-VO2 easier to turn from the insulating monoclinic phase into the metallic rutile phase. The systematic experiments and theoretical analysis demonstrate that the temperature-induced in-suit MIT property endows the W-VO2 catalyst with strong chemisorption against polysulfides, low energy barrier for liquid-to-solid conversion, and outstanding diffusion kinetics of Li-ion under high temperatures. Benefiting from these advantages, the Li-S batteries with W-VO2 modified separator exhibit significantly improved rate and long-term cyclic performance under 50°C. Remarkably, even at an elevated temperature (80°C), they still exhibit superior electrochemical performance. This work opens a rewarding avenue to use phase-changing materials for high-temperature Li-S batteries.

A novel Magnéli-phase Ti9O17-containing anode by controlled reductive decomposition of calcium copper titanate perovskite under hydrogen atmosphere for paracetamol degradation

CaCu3Ti4O12 (CCTO) materials show high efficacy in water treatment due to their perovskite structure and exceptional chemical stability. Their combination with electro-oxidation and sulfate-based advanced processes represents a promising approach for water treatment applications. CCTO can be modified through various processes to enhance its activity in water treatment. In this study, CCTO was synthesized using ball milling, and the effects of different sintering treatments were evaluated. The treatment with different atmospheres led to CCTO decomposition. Upon sintering under nitrogen, CCTO broke down into the CaTiO3, Cu2O, and rutile TiO2 phases. Conversely, sintering under hydrogen (CCTOH2) led to the reduction of Cu and TiO2 and the creation of Cu and Magnéli phase Ti9O17. CCTOH2 exhibited the highest electrochemical properties due to the presence of Magnéli phases that enhanced electron transfer and conductivity. The decomposition treatment effect on the water treatment performance was evaluated using an electro-oxidation/peroxymonosulfate system. The results showed that when CCTOH2 membranes were used as anodes, paracetamol was completely removed within 10 min. Toxicity was evaluated using Vibrio fischeri. After 1 h, bacterial luminescence inhibition rate dropped to 0 % (from ∼96 % at 2 min), demonstrating paracetamol degradation into non-toxic compounds. Furthermore, CCTOH2 efficacy was tested in the presence of dissolved and colloidal matter from a laboratory-scale secondary effluent. The results demonstrated consistent efficiency in paracetamol degradation in real water and the additional removal of fluorophores. After demonstrating the efficacy of our CCTOH2 membrane, it is now important to test it in large scale experiments.

Theoretical Prediction for Thermo-Elastic Properties of TiO2 (Rutile Phase)

Theoretical Prediction for Thermo-Elastic Properties of TiO2 (Rutile Phase)

Use of nickel-electroplating wastewater to synthesize Ni-doped TiO2 and NiTiO3 coatings by plasma electrolytic oxidation to treat hexavalent chromium in real electroplating wastewater

The use of residual water from nickel plating for the synthesis of Ni/TiO2 coatings using the PEO technique was carried out in this work. Evaluation by response surface methodology (RSM) for the studied coatings in the reduction of Cr(VI) present in chrome-plating wastewater is presented. Duty cycle variations between 2 % and 50 % on Ti substrates of 20 × 20 × 1 mm was employed to obtain the studied coatings. The coatings were characterized by XRD, AFM, SEM/EDS, XPS, and DRS, and computational analysis using DFT was performed. A strong dependence of the duty cycle on the anatase/rutile relation, surface roughness, and Ni incorporation in the coatings is showed. The sample obtained at 50 % of the duty cycle, in addition to the anatase and rutile phase, showed the formation of NiTiO3. Additionally, the incorporation of Ni in Ti sites in TiO2 as a consequence of the d orbitals of Ni, which generated a shift of the absorption band towards the visible and a decrease in the bandgap, is observed. The response surfaces obtained for the reduction of Cr(VI) in the samples of 2 % and 50 % of duty cycle, indicating that the voltage and the concentration of Cr(VI) are the variables with the greatest influence in the process, being the 2 % sample the one that presented the best performance in the photoelectrocatalysis process. In this sense, the optimal conditions for the 2 % sample were determined. Furthermore, the kinetic study to a pseudo-first order kinetic model was adjusted, and the efficiency of the material after 16 cycles of reuse is greater than ∼ 99.4 % in 10 min. Taking advantage of industrial wastewater as a resource using the PEO technique has potential applications in contributing to environmental sustainability.

Selective Photocatalytic Reduction of 3‐Nitrophenol to 3‐Aminophenol by Anatase and Rutile TiO2 – What Stands Behind the Photoactivity?

AbstractThe photocatalytic selective reduction of 3‐nitrophenol to 3‐aminophenol was studied in the presence of titanium dioxide in the form of various anatase and rutile compositions. The reaction progress is altered by various parameters, which can be classified as intrinsic (depending on the chemical, structural, and electronic features) and extrinsic (depending on the reaction and conditions). The goal of the studies was to understand the influence of intrinsic factors and to compare the performance of anatase and rutile materials. The (photo)electrochemical analysis revealed unequivocally the differences in interfacial electron transfer, charge recombination, reduction driving force, and methanol photooxidation efficiency for titania polymorphs. It appeared that all mentioned processes were phase‐dependent, and they contributed unequally to overall photocatalytic activity. In particular, methanol oxidation was the most efficient at the rutile phase, which overcame the critical limitation of the oxidation pathway and facilitated the reduction of 3‐nitrophenol. On the other hand, the dark electron transfer efficiency was highest at the anatase phase, despite the lower driving force in this case. The presented thorough and systematic analysis of the discussed photocatalytic system (the photocatalyst and the reaction) should allow the rational design of efficient and selective photocatalysts.

Effect of sintering conditions on colossal dielectric properties of (Tb1/2Nb1/2)0.01Ti0.99O2 ceramics

In this study, we investigated various sintering temperatures (1200 °C−1450 °C) and durations (2–6 h) conditions for preparing (Tb1/2Nb1/2)0.01Ti0.99O2 (TNTO) ceramics. By employing high sintering temperatures (≥1350 °C) and extended sintering durations (≥4 h), we successfully achieved ultra–high dielectric permittivity values (ε′ ∼ 2.2 − 4.1 × 104) and remarkably low loss tangent values (∼0.025−0.079). Remarkably, the temperature coefficient of the TNTO ceramic, sintered at 1350 °C, exhibited exceptional stability, maintaining a value of approximately 15% even at 200 °C. Additionally, we examined the phase structure and microstructure of the TNTO ceramics to gain insights into their colossal permittivity (CP) behavior. The analysis revealed the presence of rutile TiO2 and TbNbTiO6 phases, and the ceramics exhibited a high–density microstructure under high–temperature sintering conditions. The impedance spectroscopy analysis revealed that the primary contributor to the observed CP behavior was the interfacial polarization mechanism. The observed increase in the ε′ value, correlated with the enlargement of the average grain size, can be attributed to the effect of the internal barrier layer capacitor. However, when the sintering time ≥4 h, the grain size did not significantly affect the ε′ value, possibly due to reaching the maximum capacity of electron production for the interfacial polarization process (i.e., the maximum intensity of polarizability). This study provides valuable insights into optimizing the sintering conditions for TNTO ceramics and related compounds, laying the groundwork for the development of a new CP oxide suitable for practical applications.

Facile synthesis of N-doped TiO2 nanosheets with exposed (001) facets for enhancing photocatalytic activity

Nitrogen-doped TiO2 with exposed (001) facets was prepared by hydrothermal method using TiN as precursor. The effect of the proportion of HF and HCl on the crystal structure, morphology, optical properties and photocatalytic activity were investigated. The photocatalytic performance of N-doped TiO2 nanosheets was evaluated by the degradation of methylene blue (MB) under xenon lamp light source. The results showed that TiO2 demonstrated nanorod structure with a single rutile phase in the absence of HF while anatase TiO2 exhibited nanosheet structure with exposed (001) facets in the presence of HF. With the increase of HF addition, the degradation rate of the N-doped TiO2 decreased gradually. When the addition of HF was 1 mL, TiO2 showed the highest photocatalytic activity, which was mainly attributed to the large specific surface area and optimal percentage of exposed (001) facets.

Improvement of the performance of carbon based all-inorganic perovskite solar cells by using ammonium acetate modified rutile TiO2 nanorods array as the electron transport layer

Carbon-based all-inorganic perovskite solar cells are currently emerging as a commercial and promising photovoltaic device. Rutile TiO2 has the function of UV shielding and preventing the decomposition of perovskite, furthermore, TiO2 nanorod array provides the direct 1-D electron transmission channel. Herein, vertically oriented rutile TiO2 nanorods array are synthesized on the FTO substrate by a simple one-step hydrothermal process and used as the electron transfer layer. The analysis of characterization illustrates that the prepared TiO2 is a flawless single rutile phase. TiO2 nanorods are employed as an ETL to provide a passage for the rapid and direct charge transfer. The separation of electrons and holes can be enhanced by ammonium acetate treatment of the TiO2 nanorod ETL/perovskite interface, and the carrier recombination can be efficiently lowered. Based on the structure of FTO/TiO2@CH3COONH4/CsPbI2.25Br0.75/C, the best device containing 2.5 mg/mL ammonium acetate modified TiO2 nanorods showed a short-circuit current density of 14.55 mA/cm2, open-circuit voltage of 1.08 V, and fill factor of 69.45 %, yielding a power conversion efficiency of 11.53 %, which show an increase in efficiency of approximately 22.4% when compared with the control cell. The results show that ammonium acetate interface modification is an effective strategy to enhance the photovoltaic performance of PSCs.

Low loss tangent and excellent humidity–temperature stability with DC bias independence of giant-permittivity TiO2 doped with indium tin oxide and tantalum pentoxide

Although a high permittivity (ε′>104) of rutile TiO2 can easily be obtained by doping with Ta5+, the low loss tangent (tanδ<0.05) cannot be achieved. Furthermore, ε′ of giant dielectric oxides is usually dependent on environmental factors (temperature and humidity) and operation factors (frequency and DC bias). In this study, greatly reduced tanδ and enhanced ε′–stabilities were obtained in TiO2 by doping with Ta2O5 and indium tin oxides (ISO). Dense ceramics with homogeneously dispersion of doping elements were obtained by sintering at 1400 °C for 3 h. The rutile phase was detected with expanded lattice parameters as ISO increased, while the average grain size decreased slightly with a narrow size distribution. According to the Raman spectroscopy, oxygen vacancies in Ta2O5–doped TiO2 tended to slightly increase by doping with ISO. Besides a high ε′ of ∼2–4 × 104, low tanδ values of 0.007–0.04 (103 Hz) were achieved in the temperature range of −80 to 200 °C. The temperature coefficient of ε′ at 1 kHz from −120 to 200 °C was lower than ±10% compared to that of 25 °C. Furthermore, the ε′ was also nearly independent on the DC bias even at 300 V/cm (∼2.6%). Surprisingly, the ε′ was nearly independent on humidity over the range of 25–90%RH. Thereas, this giant dielectric material may have a great potential for capacitor applications. Impedance and dielectric spectroscopies revealed that the giant dielectric properties were caused by the interfacial polarization, while the effect of defect dipoles cannot be ignored, which could have a primary contribution in a low–temperature range.

Stabilization of the VO2(M2) Phase and Change in Lattice Parameters at the Phase Transition Temperature of WXV1-XO2 Thin Films.

Various methods have been used to fabricate vanadium dioxide (VO2) thin films exhibiting polymorph phases and an identical chemical formula suited to different applications. Most fabrication techniques require post-annealing to convert the amorphous VO2 thin film into the VO2 (M1) phase. In this study, we provide a temperature-dependent XRD analysis that confirms the change in lattice parameters responsible for the metal-to-insulator transition as the structure undergoes a monoclinic to the tetragonal phase transition. In our study, we deposited VO2 and W-doped VO2 thin films onto silica substrates using a high repetition rate (10 kHz) fs-PLD deposition without post-annealing. The XRD patterns measured at room temperature revealed stabilization of the monoclinic M2 phase by W6+ doping VO2. We developed an alternative approach to determine the phase transition temperatures using temperature-dependent X-ray diffraction measurements to evaluate the a and b lattice parameters for the monoclinic and rutile phases. The a and b lattice parameters versus temperature revealed phase transition temperature reduction from ∼66 to 38 °C when the W6+ concentration increases. This study provides a novel unorthodox technique to characterize and evaluate the structural phase transitions seen on VO2 thin films.

Self-healing of oxygen vacancies and phase transition-induced built-in electric field regulate H2 and H2O2 production

Oxygen vacancies in photocatalysts are an important parameter for improving their catalytic activities. However, this study found that oxygen vacancies do not always help with photocatalytic properties. MXene nanosheets were annealed at different temperatures to prepare nanosheets of titanium dioxide (TiO2) with anatase or rutile phase. Photo-induced self-healing of oxygen vacancies in MXene nanosheets annealed at 400 °C promoted the efficient photocatalytic evolution of hydrogen (H2) with a ∼ 6.8 mmol/g optimized yield. In contrast, the photo-induced increase of oxygen vacancies in MXene nanosheets annealed at 500 °C corresponded to an optimized ∼ 1.8 mmol/g/h yield of hydrogen peroxide (H2O2). Spectroscopic and electrochemical methods revealed that the built-in electric field between the anatase and rutile TiO2 facilitated the fast charge separation from the anatase to rutile TiO2. The photo-induced self-healing of oxygen vacancies and the phase transition-induced built-in electric field regulated the photocatalytic selectivity of H2 and H2O2 production.

Growth characteristics and wear properties of micro-arc oxidation coating on Ti-6Al-4V with different laser texture shapes

Poor wear properties severely limit the field of application and service life of titanium alloys. Three kinds of textures (dimple, groove and mesh) were prepared by laser texturing technique and compounded with micro-arc oxidation treatment to improve the tribological properties of titanium alloys in this study. The coatings' morphology, structure, and composition were characterized, and their antiwear properties were analyzed. The results show that the proportion of rutile phase in the coating increases with increasing textured area rate and that the textured edge coating has higher Si and P content, with increased thickness and densities. In terms of friction properties, the dimpled texture shows the best friction properties when textured alone, with a 28.6 % decrease in the average coefficient of friction compared to the substrate; in contrast, the meshed texture shows the best friction properties after the micro-arc oxidation treatment, with a 76.2 % decrease in the average coefficient of friction compared to the substrate. Studies have shown that laser texturing can reduce wear by retaining abrasive debris. However, laser texturing alone does not provide a significant increase in hardness at the edge location, which is more susceptible to damage during wear, leading to more severe wear. The “tip effect” encourages the growth of a micro-arc oxide layer, and the resulting hardness of the layer helps protect the texture structure from damage. The synergistic effect of the texture and the rough, hard structural features of the coating itself enhances the wear resistance of the composite coating.

Structural analysis and photocatalytic degradation towards methylene blue using (Nb0.5Si0.5)xTi1−xO2 nanocomposites

(Nb0.5Si0.5)xTi1−xO2 nanocomposites (x = 0, 0.025, 0.05, and 0.1) were produced by the easy and versatile mechanical milling technique. Structural parameters, optical absorbance, surface area, and photocatalytic performance towards methylene blue (MB) under ultraviolet–visible (UV–Vis) radiation were investigated. The structural analysis revealed the formation of rutile and brookite phases, confirming the good incorporation of Nb0.5Si0.5 inside the TiO2 lattice. The crystallite size of formed phases was slightly affected by the dopant and its average value is in the range of 5–7 nm. The morphology of composites is composed of spherical-like nanoparticles with an average particle size range of 10–22 nm, and the highest surface area (19.19 m2/g) was reached for (Nb0.5Si0.5)0.025Ti0.075O2. The FTIR, Raman, and XPS analyses indicated the formation of numerous Ti–O–Ti, Si–O–Ti, and Si–O–Si bonds and emphasized the formation of rutile and brookite phases. The optical band gap obeyed the direct transition mechanism, and its average values were 3.4, 3.82, 3.7, and 3.5 eV for x = 0, 0.025, 0.05, and 0.1, respectively. The photodegradation efficiency (η) of TiO2 towards MB was enhanced by Nb0.5Si0.5 doping, catalyst dosage, pH value, and irradiation time. The maximum value of η towards MB was 76.6 % and was attained after UV–Vis irradiation for 140 min in the presence of 1 g of (Nb0.5Si0.5)0.025Ti0.075O2 catalyst per 1 L MB, with the highest rate kinetic constant of 1.02 × 10−2 min−1. The value of η increased up to 94.34 % by adjusting the pH to 10. The optimum catalyst dosage for the MB photodegradation (96.4 %) is 2 g/L. Moreover, the recycling experiments demonstrated adequate reusability for the investigated catalyst. Furthermore, the adsorbed dye on the surface of the catalyst has been investigated and the degraded products were analyzed using the GC-MS technique, with a postulated mechanism of degradation. Therefore, the prepared (Nb0.5Si0.5)xTi1−xO2 nanocomposites are suitable for the degradation of various toxic dyes and may apply to various technologies required for modulated optical band gaps such as UV photodetector.