TiO2 Phase Research Articles

Green synthesis of TiO₂ phases for efficient photocatalytic degradation of oxytetracycline in real aquaculture wastewater

The increasing use of antibiotics, particularly oxytetracycline (OTC), in aquaculture has raised concerns about environmental pollution and the spread of antibiotic-resistant bacteria. This study investigates the photocatalytic removal of OTC in real aquaculture wastewater using green-synthesized titanium dioxide (TiO₂) derived from Neem leaves. Three phases of TiO₂ were successfully synthesized, namely anatase, rutile, and brookite, with their properties evaluated using XRD, FESEM, photocurrent response, EIS, and photoluminescence. Among the phases studied, Neem-Anatase TiO2 demonstrated superior performance, achieving 86.63 % ± 2.7 % antibiotic degradation in pure OTC aqueous solution. With a band gap of 3.15 eV, Neem-Anatase TiO₂ exhibited light absorption capability 1.5 and 6 times greater than Neem-rutile (3.4 eV) and Neem-brookite (3.71 eV), respectively. Neem-Anatase TiO₂ maintained a 69.3 % ± 1.2 % degradation efficiency over four recycling cycles, and hole radicals was determined as the primary radical species involved in the photocatalytic process. In real aquaculture water, the Neem-Anatase TiO2 OTC degradation performance could achieve 69.63 % ± 3.4 % after optimizing experimental parameters including the initial Neem-Anatase TiO2 dosage (0.6 mg/mL), initial OTC concentration (10 ppm), pH (pH 6) and hydrogen peroxide concentration (5 mM) using the Design Expert software. Factors contributing to the reduction of OTC removal efficiency in aquaculture water include the screening and scavenging effect by the dissolved solids, organic and inorganic components in the water. This work demonstrates the potential of green-synthesized TiO₂, particularly the anatase phase, as a sustainable solution for antibiotic pollution in aquaculture wastewater thereby mitigating environmental impacts and limiting antibiotic resistance in aquatic ecosystems.

Effective attainment of a substantial proportion of the PbTiO3 crystalline phase through a non-isothermal crystallization process

The crystallization kinetics studies were performed on a lead–titanium borate glass with a composition 50PbO–25TiO2–25B2O3 (mol %) to well understand the crystallization process by a non-isothermal method in an attempt to obtain a substantial proportion of the lead titanate (PbTiO3) crystalline phase. Based on the DTA result, the glassy material was heat-treated to induce crystallization and then produced a glass-ceramic. The broad hump observed in the XRD patterns of a glassy sample affirmed its amorphous nature. However, XRD studies conducted on a glass-ceramic revealed the evolution of the crystalline phase of PbTiO3 and a minor phase of TiO2. The phase relationship of PbTiO3 resulting from the reaction between PbO and TiO2 during a non-isothermal crystallization process has been examined. The activation energy for the crystallization of PbTiO3 is evaluated to be 135 kJ/mol (at PbO/TiO2 ratio = 2/1 mol %). When the Pb/Ti ratio exceeds 1, the process progresses nearly to completion by the first crystallization peak, and the PbTiO3 phase formation is easier. The fraction of PbTiO3 phase in the present glass is 98.3 % at PbO/TiO2 ratio = 2/1 mol %. In addition, FTIR spectra provided the presence of Ti4+ ions in the glass-ceramic. According to the values of crystal growth and Avrami index, surface crystallization and one-dimensional growth mechanisms are suitable mechanisms for contributing to the crystallization of this glassy sample. The obtained findings provided details on the crystallization behaviour of this glassy sample and excellent insight into obtaining the PbTiO3 crystalline phase in a large proportion, which is of great importance in future technological applications.

Phase-dependent photo-assisted electrocatalytic conversion of nitrate to ammonia using TiO2: Insights into amorphous and rutile activity

The rise in nitrogen-containing compounds in water sources due to modern agricultural practices has intensified the need to effectively convert nitrate to ammonia, a valuable fertiliser and fuel. We developed a photo-assisted electrocatalytic system using a NiO/Au plasmon/TiO2 composite to selectively reduce nitrate to ammonia under visible light, at neutral pH, and at room temperature. TiO2 was found to be the active catalyst, but the precise active structure responsible for each catalytic step remains unclear, as the reaction involves a complex, multistep process. By analyzing the catalytic activity of different TiO2 phases, we found that amorphous TiO2 significantly enhances the nitrate-to-nitrite reduction step, increasing nitrite concentration in solution by nearly 50 % and resulting in a 10 % increase in Faradaic efficiency for this product. Conversely, the rutile phase plays a crucial role in the subsequent conversion of nitrite to ammonia. When the rutile phase was present, the ammonia yield more than doubled, leading to a 30 % increase in Faradaic efficiency. This phase-dependent behaviour provides critical insights into improving nitrate reduction efficiency, enabling sustainable agricultural practices that recycle nutrients, reduce fertiliser costs, and promote economic sustainability.

Greatly enhanced humidity sensing performance with ultra-low hysteresis error in giant permittivity TiO2 ceramics co–doped with Sc3+ and Ta5+ ions

This study investigates the dielectric and humidity sensing properties of ScyTa0.025Ti0.975-yO2 (y%ScTTO) ceramics with varying Sc3+ concentrations (1 %, 2.5 %, and 5 %). The ceramics were synthesized using a solidstate reaction method. Xray diffraction analysis confirmed the presence of the main rutile TiO2 phase without any impurity phases. The ceramics exhibited a highdensity microstructure with a relative density exceeding 92 %. The mean grain size increased with higher Sc3+ doping concentrations. Elemental mapping showed homogeneous dispersion in the 1 %ScTTO and 2.5 %ScTTO samples, while the 5 %ScTTO sample exhibited segregation of a Scrich phase along the grain boundaries. All samples demonstrated a giant dielectric constant of 103–105, which decreased as the Sc3+ concentration increased. Notably, the 1 %ScTTO and 2.5 %ScTTO samples displayed significant humidity sensitivity. The capacitance of these samples increased by 100 % and 1700 %, respectively, as the relative humidity increased from 30 % to 90 %. Remarkably, the 2.5 %ScTTO sample exhibited minimal hysteresis error, measured at 1.09 % at 1 kHz. Furthermore, these samples showed very fast response and recovery times, ∼1 and 0.15 min, respectively. The humidity sensing properties at 1 kHz and 25 °C remained stable under a DC bias of up to 12 V but showed a significant increase when the temperature was raised to 50–75 °C (without DC bias). The enhanced humidity sensing performance and giant dielectric response were attributed to the formation of defects and the grain boundary effect.

Enhanced ablation resistance and mechanical behavior of spark plasma sintered ZrB2-SiC composites with TiC addition

The study evaluated the ablation resistance and mechanical behavior of spark plasma sintered ZrB2-25 vol% SiC-TiC (5–15 vol%) composites. The addition of TiC improved ablation resistance by promoting the formation of ZrO2.TiO2 and TiO2 phases on the oxidized composites. The ZrB2-25 vol% SiC-15 vol% TiC composite exhibited the lowest mass ablation rate of 0.11 mg/s and maximum fracture toughness of 5.8±0.29 MPa.m0.5. After ablation, SiC particle pull-out, crack deflection and crack bridging were identified as the primary toughening mechanisms. The maximum microhardness of 23.01±1.18 GPa and compressive strength of 1688.2±75.5 MPa were obtained for the ZrB2-25 vol% SiC-10 vol% TiC composite, which correspond to 92.86 % and 94.31 % of their respective maximum values prior to ablation. Furthermore, nanoindentation studies revealed significant improvements in both elastic modulus and nanohardness with the addition of TiC due to reduction in porosity and refinement in SiC grain size. After ablation, the elastic modulus and nanohardness reduced. However, the ZrB2-25 vol% SiC-10 vol% TiC composite retained a maximum elastic modulus of 433.61 GPa and nano-hardness of 21.88 GPa. The oxidation behavior of ZrB2-SiC composites containing TiC was analyzed at 1500°C for 6 hours in air. The TiC-containing composite exhibited lower mass gain, lower parabolic oxidation rate constant and a thin oxide layer compared to the ZrB2-SiC composites.

Cu2O/TiO2 Heterostructure‐Based Photoelectrochemical Photodetector with Enhanced Performance and Stability

Cu2O/TiO2 heterostructure is prepared by electrodepositing Cu2O on rutile phase TiO2 particles. The morphology, structural, and optical properties of Cu2O/TiO2 heterostructure are determined by scanning electron microscopy, Raman spectroscopy, X‐ray diffractometer, and UV–vis absorption spectrum. The Cu2O/TiO2 heterostructure photoelectrochemical‐type photodetector is constructed based on this heterostructure. Experimental results show that the photoresponsivity and visible light absorption of the Cu2O/TiO2 heterostructure are significantly enhanced compared to those of TiO2 and Cu2O which demonstrate that the Cu2O/TiO2 heterostructure with a special interfacial structure is conducive to accelerating the separation and transfer of photogenerated carriers. The photoresponsivity and photocurrent density of Cu2O/TiO2 can reach 154 μA W−1 and 15.6 μA cm−2 at 0 V. In addition, the photocurrent density of the Cu2O/TiO2 heterostructure steadily increases with the enhancement of irradiation power density. Moreover, no significant attenuation of the photocurrent density is observed in the prepared Cu2O/TiO2 heterostructure after 1800 s of photo‐on/off cycles. These results suggest that the Cu2O/TiO2 heterostructure‐based photodetector holds great potential in the photodetection field.

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

Photocatalytic performance and solar cell simulations of TiO2–SnO2:F mixed oxide thin films grown by spray pyrolysis method

Mixed oxide titanium dioxide (TiO2) and fluorine doped tin oxide (SnO2:F) thin films have been grown, using spray pyrolysis technique, at various substrate temperatures (Ts) ranging from 250 to 400 °C with a step of 50 °C. Samples were examined using X-ray diffraction (XRD), optical microscopy, spectrophotometry and spectrofluorimetry, with special emphasis on the evolution of their physico-chemical properties versus substrate temperature. In fact, X-ray diffraction analysis showed that a substrate temperature of about 350 °C exhibits the presence of both anatase phase of TiO2 and tetragonal structure of SnO2:F compounds. A direct band gap of about 3.91 eV was obtained. Envelope method, based on transmission spectrum, was investigated in order to estimate the film thickness and some optical parameters such as real and imaginary parts of dielectric constant. Wemple Di-Dominico and Spizer Fan models were applied in order to determine the effect of substrate temperature on some dispersion parameters. Photoluminescence spectra showed different emissions in the visible region. The photodegradation mechanism of both Rhodamine B (RhB) and Malachite Green (MG) pollutants using TiO2–SnO2:F coupled oxide layer, grown at 350 °C, was discussed and an efficiency of about 90 %, after 3 h of sun irradiation, was achieved. Additionally, the layer exhibits good stability, recoverability and reusability after a cyclic test of 9 h, making it suitable for industrial applications. As a secondary application, a numerical simulation of TiO2–SnO2:F/CdS/CIGS solar cell, using SCAPS-1D software, was investigated for the first time. An open circuit voltage of about 613 mV was obtained, the current density Jsc was in the order of 33.49 mA/cm2, the Fill Factor FF and the efficiency were in the order of 79.13, 16.23 %, respectively.

Synthesis and Evaluation of Novel Ternary MgFe2O4/CuO/TiO2 Nanocomposite for Visible Light Photodegradation of Malachite Green Dye

Novel ternary MgFe2O4/CuO/TiO2 nanocomposite was synthesized using the sol-gel method at low temperatures. The XRD, FTIR, SEM-EDX, TEM, UV-visible DRS and VSM techniques were used to characterize the structure, shape, optical, morphology and magnetic properties. The XRD examination revealed typical peaks in nanocomposites, including the anatase phase of TiO2 with an average diameter of 9 nm, consistent with the TEM data. The SEM morphology examinations revealed spherical particles, while EDAX analysis indicated the corresponding components (Fe, Ti, O, Mg and Cu) in the prepared nanocomposites. The UV-DRS measurements revealed that the synthesized nanocomposite has a band-gap energy of 2.30 eV. The vibrating sample magnetometer (VSM) was used to trace the M-H loop of MgFe2O4, yielding magnetic parameters such as saturation magnetization (Ms). The catalytic activity of the as-prepared sample was examined by the degradation of malachite green dye under visible light and UV irradiations. The photocatalytic studies demonstrated that MgFe2O4/CuO/TiO2 nanocomposite showed 100% degradation efficiency towards malachite green dye. Under visible light and UV irradiations, the synthesized MgFe2O4/CuO/TiO2 sample with a molar ratio of 0.8:0.1:0.1 demonstrated good catalytic efficiency. The antibacterial activity investigations were done against Gram-negative Escherichia coli, Klebsiella pneumonia, Gram-positive Staphylococcus aureus and Bacillus subtilis bacteria utilizing nanocomposites.

The Effect of Heat Treatment on the Sol–Gel Preparation of TiO2/ZnO Catalysts and Their Testing in the Photodegradation of Tartrazine

This study aims to synthesize TiO2/ZnO powders and to study the effect of heat treatment on their photocatalytic ability against the Tartrazine anionic dye. The as-obtained powders with the following compositions—90TiO2/10ZnO and 10TiO2/90ZnO (mol%)—were obtained by the sol–gel technique. The prepared gels were annealed at 500 °C and 700 °C and subsequently characterized by XRD, UV–Vis, and SEM methods. The single crystalline phase of TiO2, which has been detected at up to 500 °C is anatase, while for ZnO, it is the hexagonal wurtzite structure. Further increases in the temperature (700 °C) led to the appearance of rutile in the samples. The SEM analysis demonstrated that the binary oxide materials had irregular shaped particles with a tendency to agglomerate. The UV–Vis spectra of the gels exhibited a red shift in the cut-off of the 90TiO2/10ZnO sample compared with pure Ti(IV) butoxide. Photocatalytic tests showed that the investigated samples possessed photocatalytic activity toward Tartrazine. Compared with TiO2, the prepared TiO2/ZnO photocatalysts showed superior properties in the photodegradation of a Tartrazine water solution. The target photocatalysts’ enhanced photocatalytic activities can be explained by their reduced band gap energy, improved surface physicochemical characteristics, separation of photo-induced electron–hole pairs, and lowered recombination rate. Higher photocatalytic activity was observed for powders annealed at 500 °C, with the 10TiO2/90ZnO (mol%) sample exhibiting the highest photocatalytic degradation of the used organic dye.

Synthesis and Characterization of TiO2 -CQDs Nanocomposites and Testing of Their Anticancer Potential

This work used a green approach to produce carbon quantum dots (CQDs). TiO2 nanoparticles (NPs) and TiO2–CQDs nanocomposites with different weight ratios of CQDs were organized through a facile sol-gel method. XRD showed that the anatase and rutile phases of TiO2 were polycrystalline with a tetragonal structure and that the CQDs exhibited a broad peak at (002) and a hexagonal structure. High resolution-transmission-electron microscopy revealed that the TiO2 NPs agglomerated in mostly spherical shapes and that the anatase and rutile phases of TiO2 had sizes of less than 15 and 25 nm, respectively. The CQDs had a relatively uniform diameter, a spherical shape with a highly crystalline structure, and a size below 2 nm. UV–visible spectroscopy revealed that the absorbance of the TiO2- CQDs nanocomposites increased with the increase in CQD ratio. The energy band gaps of the anatase and rutile phases were 3.07 and 2.7 eV, respectively, whereas that of CQDs was 3.14 eV. Meanwhile, the energy band gaps of the TiO2–CQDs nanocomposites decreased with the increase in CQDs ratio. The growth inhibition rates of the liver cancer HepG2 cell line and the normal cell line RD were measured after 24 hours of experience to the two TiO2 phases and TiO2–CQDs nanocomposites. The cytotoxicity test presented that the tested substances were extremely harmful to cells in cancer. Inhibition rates increased with the increase in CQDs ratio. The inhibition rate of growth in cancer cells, including the liver cancer HepG2 cell line and the normal cell line (RD), was measured for 24 hours after they were exposed to TiO2 (two phases) and TiO2-CQDs nanocomposites. The samples showed a slight effect on the normal line (RD) compared to HepG2 cancer. The highest inhibition rate was 12.11% for the CQD 0.7 sample.

Review of Bio-Inspired Green Synthesis of Titanium Dioxide for Photocatalytic Applications

Titanium dioxide (TiO2) is an important photocatalyst that is widely studied for environmental applications, especially for water treatment by degradation of pollutants. A range of methods have been developed to produce TiO2 in the form of nanoparticles and thin films. Solution-based synthesis methods offer the opportunity to tune the synthesis through a choice of reagents, additives and reaction media. In particular, the use of biomolecules, such as proteins and amino acids, as bio-inspired additives in TiO2 synthesis has grown over the last decade. This review provides a discussion of the key factors in the solution-based synthesis of titania, with a focus on bio-inspired additives and their interaction with Ti precursors. In particular, the role of bio-inspired molecular and biomolecular additives in promoting the low-temperature synthesis of titania and controlling the phase and morphology of the synthesised TiO2 is discussed, with a particular focus on the interaction of TiO2 with amino acids as model bio-inspired additives. Understanding these interactions will help address the key challenges of obtaining the crystalline TiO2 phase at low temperatures, with fast kinetics and under mild reaction conditions. We review examples of photocatalytic applications of TiO2 synthesised using bio-inspired methods and discuss the ways in which bio-inspired additives enhance photocatalytic activity of TiO2 nanomaterials. Finally, we give a perspective of the current challenges in green synthesis of TiO2, and possible solutions based on multi-criteria discovery, design and manufacturing framework.

Tailoring Interface via Tuning the Phase and Morphology of TiO2 for Efficient Mesoporous Perovskite Solar Cells.

The efficiency of mesoporous perovskite solar cells (mp-PSCs) is significantly influenced by favorable charge transport properties across their various interfaces. The interfaces involving compact-TiO2, mesoporous electron transport layer (ETL), and perovskite layer are particularly vital for high-performing devices. Our study presents a combined experimental and computational approach, specifically employing density functional theory, to explore the impact of mesoporous-ETL/perovskite interface properties on carrier transport. These properties are examined in relation to the phases and morphologies of the mesoporous layer. Different phases of TiO2, including anatase, rutile, and brookite, and various morphologies such as nanocubes, nanorods, and disks/clusters, were synthesized using a simple hydrothermal synthesis route. They constitute the mesoporous layer, and Cs0.05FA0.84MA0.14PbI2.55Br0.45 is used as the perovskite absorber in mp-PSCs. The performance of the resulting mesoporous-TiO2 (mp-TiO2) device was investigated in relation to the different phases and morphologies of mp-TiO2. The mp-PSCs with the anatase phase as the mesoporous ETL exhibited the highest device parameters, including power conversion efficiency of 19.15%, short-circuit current density of 22.55 mA/cm2, fill factor of 76.50%, and open-circuit voltage of 1.11 V. The superior performance of the anatase structure is attributed to its promising band edge alignment, which results from a small negative conduction band offset compared to other phases, thereby enhancing carrier transport. This study underscores the potential of interface optimization to improve device performance. By investigating the device performance across different phases and morphologies of the mp-TiO2 layer, we can pave the way for the design of next-generation energy devices.

Titanium Dioxide and Photocatalysis: A Detailed Overview of the Synthesis, Applications, Challenges, Advances and Prospects for Sustainable Development

The term “photocatalysis” has recently gained high popularity, and various products using photocatalytic functions have been commercialized. Of all the materials that may be used as photocatalysts, titanium dioxide (TiO2) is virtually the only one that is now and most likely will remain appropriate for industrial application. Water and air purification systems, sterilization, hydrogen evolution, self-cleaning surfaces, and photoelectrochemical conversion are just a few of the products and applications in the environmental and energy domains that make extensive use of TiO2 photocatalysis. This is due to the fact that TiO2 has the lowest cost, most stability, and most effective photoactivity. Furthermore, history attests to its safety for both people and the environment because it has been used as a white pigment since antiquity. This review discusses some important aspects and issues concerning different synthesis methods and their influence on the structure and properties of TiO2, as well as the concept of photocatalysis based on it as a promising biocompatible functional material that has been widely used in recent years. The advantages of TiO2 applications in various fields of science and technology are discussed, including environmental protection, photocatalysis including self-cleaning surfaces, water and air purification systems, hydrogen liberation, photovoltaic energy, cancer diagnosis and therapy, coatings and dental products, etc. Information on the structure and properties of TiO2 phases is presented, as well as modern methods of synthesizing functional materials based on it. A detailed review of the basic principles of TiO2 photocatalysis is then given, with a brief introduction to the modern concept of TiO2 photocatalysis. Recent advances in the fundamental understanding of TiO2 photocatalysis at the atomic-molecular level are highlighted, and advances in TiO2 photocatalysis from the perspective of design and engineering of new materials are discussed. The challenges and prospects of TiO2 photocatalysis are briefly discussed.

Synthesis and design strategies of codoped titanium dioxide with band alignment and multiple reflections of incident light for efficient visible light activity

To increase the visible-light photocatalytic performance of Titania, it was codoped with specific elements and was effectively synthesized. The goal of enhancing visible-light photocatalytic performance was achieved by broadening its absorption spectrum in the visible light range and enhancing the quantum efficiency of the photocatalytic reaction toward the degradation of the hazardous dye methyl orange. Mixed phase photocatalyst with different percentage hierarchical secondary nanostructure has been synthesized by the combination of chemical bath deposition methods and hydrothermal. The density of the sprout-like branches changes from the concentration levels of titanium butoxide in the precursor solution. Based on the experimental analysis, a mechanism was proposed to interpret the evolution of the secondary growth. The band edge difference between anatase and TiO2(B) phases induces transfer of charge at the interface. The result revealed that in the TiO2 crystal some O-sites were substituted by N and S anions resulting in band mixing and incorporation of extra energy states in between the valence band maxima and conduction band minimum, which caused a shift towards longer wavelengths in the absorption edge. Compared with pure TiO2 nanobelt, the surface modified doped samples exhibited good visible light activity. The combined effect of fast charge transfer in the atomic level contact between two phases and localized N 2p and S 3p band above valence-band edge in the same material makes titanium dioxide suitable for use in the presence of visible light.

Synthesis of titanium-vanadium oxide thin films through thermal oxidation process for their use in CO gas sensing application

The thermal oxidation of evaporated titanium-vanadium thin films was carried out at different post-annealing temperatures. The structural, morphological, compositional, optical, electrical, and gas sensing properties of titanium-vanadium oxide thin films were primarily investigated. The results of the XRD study and Raman spectroscopy verified the presence of the orthorhombic V2O5, tetragonal TiO2, and monoclinic V2Ti3O9 phases. The crystallinity of TVO thin films was improved at higher annealing temperatures. The grain size (seen from SEM images) and oxygen compositions (obtained from EDS measurement) of TVO samples are also enhanced when the post-annealing temperature is increased from 500 to 575 °C. From the transmittance curves, the bandgap values for TVO samples were estimated and found in the range of 2.14–2.36 eV. The n-type conductivity of TVO films was confirmed by the negative Hall coefficient values. At last, the CO gas sensing response of TVO thin films was analyzed by monitoring the change in the surface electrical resistances at different operating temperatures and CO gas concentrations. The dynamic and static resistances were assessed at different operating temperatures varying from 100 to 300 °C. The TVO sample prepared at 550 °C showed the best conditions by examining the materials and CO sensing properties.

Aquathermolysis of polyolefin plastic wastes over a MOF-derived TiO2 anatase catalyst: Enhancing C–N bond cleavage and coke suppression

Plastics are ubiquitous in modern society owing to their cost-effectiveness, low weight, and durability. However, the disposal and recycling of plastic waste remain significant challenges. Aquathermolysis has emerged as a promising strategy for converting contaminant-rich polyolefin plastic waste into value-added liquid fuels. This study investigates the plastic-waste aquathermolysis potential of a TiO2 catalyst derived from the sacrificial precursor Ti-containing MIL-125 via a MOF-mediated synthesis pathway combined with calcination. The TiO2 catalyst retained its mesoporous properties and predominantly anatase phase on calcination at 450 ℃. The aquathermolysis catalysis and stability of the newly synthesized catalyst for plastic-waste conversion were evaluated and compared with those of other catalytic systems. Additionally, the role of water in the N removal efficiency and coke suppression properties of the catalyst were analyzed. Water significantly improved the removal of N and S impurities, with a N reduction of 80–95% at the optimal water content (20–40 wt%). The robustness of the as-synthesized catalyst was confirmed by deconvoluted X-ray photoelectron spectroscopy patterns, which indicated the persistence of the TiO2 phase, even after prolonged catalysis in aqueous environments, and transmission electron microscopy results, which showed that the anatase phase remained well-dispersed under aquathermolysis conditions with a significant reduction in the C/Ti ratio and a corresponding increment in the N/C ratio. The results of this study could guide future research on the development of catalysts, similar to the MIL-125-derived TiO2 catalyst investigated here, with high potential for efficient plastic-waste conversion and impurity removal in aqueous environments.

Sintering activation energy and low-temperature sinterable process of Boron-lanthanide glass/Li2Zn3Ti4O12 ceramic composite systems for LTCC technology

This work investigates the characteristics of wettability, activation energy for sintering, evolution of phase structure, and behavior during the low-temperature sintering process of B2O3-La2O3-MgO-TiO2 (BLMT) glass/Li2Zn3Ti4O12 ceramic composites for low temperature co-fried ceramics technology (LTCC). As the BLMT glass content increases from 0 to 10 wt%, the average sintering activation energy (Ea) of the composite decreases from 450 ± 8 to 356 ± 37 kJ/mol. There are two phases the primary Li2Zn3Ti4O12 phase and the secondary LaBO3 phase, the latter precipitates from the BLMT glass after sintering at 700 °C. This indicates that BLMT glass promotes the sintering of Li2Zn3Ti4O12 ceramic below 900 °C. In composites containing 20 wt% or more glass, sintering is governed by both liquid-phase sintering and reactive viscous sintering. As the BLMT glass content increases, the impact of viscous flow on the densification process becomes more pronounced. Simultaneously, when the glass content is greater than 20 wt%, the glass precipitates LaBO3, TiO2, and MgLaB5O10 phases between 700 and 750 °C. After 850 °C, the glass melts and reacts with Li2Zn3Ti4O12 phase to produce a new TiO2 phase. Accordingly, the activation energy (Ea) of sintering the composite material increases from 393 ± 17 to 667 ± 1 kJ/mol.

Hybrid magnetic nanocomposite NiFe2O4/TiO2 for Photocatalytic dye degradation and green hydrogen (H2) generation

The present paper focuses on designing and developing nanocomposites to modify their properties to increase the ability to generate hydrogen and degrade photocatalytic dyes. A nanocomposite of nickel ferrite (NiFe2O4)/Titanium dioxide (TiO2) was formulated using the sol-gel self-ignition method. X-ray diffraction (XRD) tool was adopted to analyze the structural behavior of pure nickel ferrite (NiFe2O4), pure titanium dioxide (TiO2), and nanocomposite of NiFe2O4/TiO2. XRD pattern of NiFe2O4 and TiO2 shows a monophasic nature whereas the XRD pattern of nanocomposites shows mixed phases of NiFe2O4 and TiO2. FTIR spectra confirm the formation of NiFe2O4, TiO2, and their composites with absorption bands near 400 cm-1 and 600 cm-1, 1500 cm-1. Raman spectra unveiled the presence of five active Raman modes in the case of NiFe2O4 whereas three active Raman modes are seen in TiO2. Field emission scanning electron microscopy (FE-SEM) images exposed the dense structure with spherical cluster-like morphology in the case of NiFe2O4. Energy-dispersive X-ray spectroscopy (EDX) analysis confirms the presence of all the desired elements of NiFe2O4, TiO2, and their composites in stoichiometric proportions. BET analysis of nickel ferrite NPs suggests a large surface area of the order of 31.54 m2/gm in comparison with TiO2 (19.23 m2/gm). The optical characterization was made through the UV-visible spectroscopic technique. TiO2 shows a maximum band gap of the order of 3.02 eV while NiFe2O4 shows a low band gap of the order of 1.74 eV. A typical M-H curve with saturation magnetization of the order of 27.54 emu/gm was observed for pure NiFe2O4. No magnetic properties were observed for TiO2 as it is a semiconductor. Enhancement in magnetic properties is observed with increases in NiFe2O4 content in a composite of NiFe2O4/TiO2. The photocatalytic activities were examined by degrading Methylene Blue (MB) dye under sunlight for pure nickel ferrite (NiFe2O4), pure titanium dioxide (TiO2), and a nanocomposite of NiFe2O4/TiO2. Photocatalytic hydrogen production reactions were carried out in a methanol/water solution under visible light. Consequently, the best configuration of the photocatalyst was determined as 25% wt% NiFe2O4/ TiO2 which had shown the maximum hydrogen (H2) production rate as 146.3 μmol/g/h after 8 h owing to its reduced bandgap energy and delayed e- / h+ recombination.

Enhanced efficiency, electron lifetime, and eco-friendliness of dye-sensitized solar cells using nanofibrous TiO2/ZnO composite photoanodes and natural anthocyanin sensitizer

Semiconductor is the main part of the photoanode in dye-sensitized solar cells (DSSCs). In this study, an evaluation was conducted on two different morphological shapes of TiO2/ZnO semiconductors, namely nanoparticles (NPs) and nanofibers (NFs), to enhance the efficiency of DSSCs. The nanofibrous semiconductors were fabricated using the electrospinning technique. Furthermore, a natural sensitizer, anthocyanin dye, was used to promote the environmental friendliness of the fabricated cells. These cells were then compared to those that used a synthetic dye known as N719 to determine their efficiencies. The UV–vis results confirmed the extraction of anthocyanin from black plum fruits (Syzygium cumini). The structural characteristics of the composites were examined using XRD, FE-SEM, and BET experiments. The XRD results revealed that the anatase phase of TiO2 was dominant in the crystal structure of the semiconductors, while the crystallite sizes of the composites were 25.04 nm and 12.24 nm in NPs and NFs forms, respectively. The FE-SEM analysis revealed the formation of quasi-spherical NPs with an average diameter of 48.26 ± 17.75 nm and NFs with an average diameter of 153.99 ± 26.18 nm. The BET results showed that the surface characteristics of the nanocomposite were enhanced by changing the shape from NPs to NFs. Photovoltaic studies showed that utilizing NFs semiconductors in the photoanodes of DSSCs resulted in increased conversion efficiency of light to electricity. The results of the sun simulator studies confirmed that the use of natural dye led to a decrease in the effectiveness of the DSSCs. This phenomenon can be attributed to the weaker binding of the natural dye to the photoanodes. Furthermore, the EIS investigations illustrated that the electron lifetime in the natural dye is more than twice that of N719, leading to a reduced rate of electron recombination in the Syzygium cumini extract. The TiO2/ZnO NFs photoanodes exhibited superior performance compared to their nanoparticle counterparts in DSSCs. Their high surface area promoted superior dye adsorption and light absorption. Moreover, the interconnected nanofiber network facilitated efficient electron transport, minimizing recombination losses. Increasing the binding strength of the chosen natural dye to the photoanode will also make the cells more environmentally friendly and improve their ability to produce electricity.