Search Results (1,306)

Black TiO₂-impregnated electrodes were prepared via a modified dip-coating method, using six deposition layers to investigate the influence of the TiO₂ precursor phase (anatase, rutile, and P25) on their structural and optical properties, as well as their photoelectrooxidation performance toward acetaminophen degradation. A reductive thermal treatment under a H₂/Ar atmosphere successfully modified the band gap energy and promoted the formation of oxygen vacancies (Vo) and Ti³⁺ species, as evidenced by UV–Vis diffuse reflectance spectroscopy and photoluminescence analysis. Among the precursor phases, anatase exhibited the most significant band gap reduction, whereas rutile and P25 showed greater structural stability after the reduction process. Photoelectrochemical experiments revealed that the supporting electrolyte plays a dominant role in the degradation process, with significantly higher removal efficiencies observed in chloride medium (0.1 M NaCl) compared with sulfate medium (0.1 M Na₂SO₄) due to the formation of active chlorine species. Among the tested materials, rutile- and P25-derived electrodes showed the highest degradation efficiencies, reaching concentrations (C/C₀) of 0.631 and 0.650, respectively. The results highlight the combined influence of precursor phase, defect structure, and electrolyte composition on the photoelectrooxidation behavior of black TiO₂ electrodes and provide insights for the design of electrochemical systems for pharmaceutical contaminants removal. Full article

The pharmaceutical industry is a major source of pollution in wastewater effluents, characterized by chemical residues that are complex and difficult to degrade. Naproxen, a commonly detected drug in sewage effluents, exceeds safe concentrations for aquifers and is highly persistent, posing significant risks to aquatic life and ecosystems. This drug is known to cause long-term side effects in humans, such as gastrointestinal ulcers and nephrosis, associated with frequent and prolonged use. Additionally, the recent pandemic has led to a marked increase in drug consumption over a short period, exacerbating environmental contamination. Titanium dioxide has been extensively used as a photocatalyst in recent decades, proving effective in reducing these emerging pollutants. In this study, TiO₂ doped with cerium was synthesized using the sol–gel method, with cerium concentrations varied at 1, 3, 5, and 10% by weight. The resulting nanocatalysts were characterized through nitrogen physisorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-Vis diffuse reflectance spectroscopy. Photocatalytic activity was assessed using a UV-Vis spectrophotometer to monitor the degradation of the drugs. XRD analysis confirmed the crystallinity and anatase phase of TiO₂. UV-Vis diffuse reflectance spectra indicated a decrease in bandgap energy of up to 3.00 eV compared to pure TiO₂. The materials demonstrated significant degradation of naproxen (NPX) and acetaminophen (ACTP), both prepared at 30 ppm, over a 6 h reaction period. Full article

The Akseki–Kuyucak bauxite deposits, located in the Western Taurus Belt in southwestern Türkiye, represent karst-type bauxite mineralization derived from carbonate platform phases. This work integrates field observations, X-ray diffraction (XRD) analysis, and extensive geochemical data, including major, trace, and rare earth elements (REEs), to clarify the mineralogical characteristics, geochemical processes, and genetic implications of the deposits. Field and petrographic investigations indicate that the bauxite deposits occur as irregular fills and lens-shaped formations on paleokarstic surfaces of carbonate substrates. The XRD examination reveals that the major minerals in the bauxite samples are boehmite, hematite, and anatase, with some samples exhibiting a predominance of calcite, indicating a strong genetic relationship between the ore bodies and the carbonate host rocks. Major oxide analysis reveals a distinct compositional disparity between bauxitic and carbonate-dominated materials: bauxitic samples exhibit elevated Al₂O₃ and Fe₂O₃ levels, with reduced SiO₂ and CaO concentrations. In contrast, carbonate-rich samples show higher CaO and loss-on-ignition values. Ternary discrimination diagrams categorize most bauxitic samples into the ferritic bauxite and robust lateritization domains, indicating substantial weathering and residual enrichment processes. The trace element and REE studies reveal ΣLREE values ranging from 22.3 to 240.2 ppm, with a right-skewed distribution indicating heterogeneous enrichment. Correlation studies indicate that ΣLREE has a positive correlation with SiO₂ and K₂O, suggesting that the enrichment of REEs is more closely associated with silicate/clay minerals than with iron oxide phases. Furthermore, spider diagrams and the study of immobile components emphasize the significance of residual concentration processes in bauxitization. In contrast, modest TiO₂ levels indicate a composite source derived from both insoluble carbonate remnants and detrital siliciclastic materials. In summary, the Akseki–Kuyucak deposits are categorized as intricate karst bauxite systems, characterized by significant lateritization, regulated accumulation governed by paleokarst characteristics, and a complex geochemical evolution. The results demonstrate that integrating mineralogical, geochemical, and statistical methods provides a thorough framework for evaluating REE behaviors and the effects of source-related factors in karst bauxite deposits. Full article

Biotemplated strategies inspired by natural architecture have emerged as an effective strategy to improve the performance of photocatalytic materials. In this work, TiO₂-based photocatalysts were synthesized using olive leaves as a biological template to reproduce their hierarchical microstructure and enhance photocatalytic hydrogen production. The artificial olive leaf (AOL) support was obtained through a biotemplated ion-exchange process followed by hydrolysis and calcination. It was then modified by photodeposition of Au or Pt nanoparticles. The materials were characterized by SEM, XRD, N₂ adsorption–desorption, UV–Vis spectroscopy, and XPS to evaluate their structural and optical properties. SEM confirmed the successful replication of both the external morphology and internal architecture of the olive leaf, while XRD revealed low crystallinity with anatase as the only TiO₂ phase. Optical characterization showed a reduced band gap (~2.97 eV), and extended absorption toward the visible region, with Au nanoparticles exhibiting a plasmonic band at ~550 nm, whereas Pt enhanced light-harvesting efficiency. XPS indicated the presence of oxygen vacancies and Ti³⁺ species that promote metal–support interactions. Photocatalytic glycerol photoreforming showed a strong enhancement in hydrogen production after noble metal incorporation, reaching up to 14-fold under UV irradiation and 23-fold under simulated solar light for the Pt-modified catalyst, highlighting the synergy between biotemplated structuring and noble metal deposition. Full article

This study reports that titanium nanoparticles can be used as a surface coating to enhance the corrosion resistance of 316 stainless steel. It specifically examines the influence of the deposition temperature (T_dep) on the coating’s structural and morphological properties, including corrosion behavior. TiO₂ nanoparticles were thoughtfully deposited on steel substrates at temperatures of 300, 400, and 500 °C using a horizontal hot-wall tubular reactor. This equipment was expertly engineered at the CIDETEQ laboratory through the metal–organic chemical vapor deposition (MOCVD) concept. Titanium isopropoxide [Ti(OC₃H₇)₄] was used as the precursor for the coating synthesis. Structural analysis was conducted using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion performance was evaluated under accelerated conditions in 0.5 M H₂SO₄ using potentiodynamic anodic polarization (AP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The corrosion test indicates that increasing T_dep significantly differentiates the coating morphology and improves corrosion resistance. AP revealed that the pitting potential (E_pit) shifted to more positive values, ranging from +1.4 to +1.5 V. CV voltammograms indicated that coated samples had lower passive current densities (I_p ≈ 10⁴ to 10⁵ A/cm²) than the bare substrate. EIS analysis demonstrated that the coating deposited at 500 °C processed the most favorable electrochemical performance, resisting corrosion for over 28 days. This coating achieved the highest electrical resistance (297 kΩ·cm²) and the lowest capacitance (2.7 μF/cm²), attributed to the formation of a crystalline anatase phase composed of pyramidal-like nanoparticle agglomerates (~40 nm). The dense packing structure effectively blocks charge-transfer pathways, restricting electron and ion transfer. Finally, MOCVD-based chemical surface modification with TiO₂ nanoparticles is considered an innovative method to improve the corrosion resistance of stainless steel, thereby prolonging its durability under accelerated sulfuric acid exposure. Full article

This study investigates how sintering temperature affects phase evolution, titanium carbide (TiC) formation, and oil-repellent performance in TiO₂–carbon-coated 304 stainless-steel mesh for oil–water separation applications. Coated meshes sintered at 400, 500, 600, 700, and 800 °C were evaluated using gravity-driven oil permeation tests with 5W-20 motor oil and oil contact-angle measurements, while coating morphology, composition, and phase evolution were characterized by SEM, EDS, and XRD. Sintering temperature strongly influenced coating structure and wettability. Among the tested conditions, the mesh sintered at 600 °C showed the highest oil contact angle (105°) and the highest initial oil retention efficiency (80%), indicating the most favorable balance between oleophobicity and coating stability within the tested range. XRD analysis showed that 600 °C corresponded to the onset of the anatase-to-rutile transition and the initial formation of TiC. These results suggest that intermediate sintering temperatures can provide a favorable balance between retention of beneficial anatase content and enhanced interfacial interaction within the TiO₂–carbon coating. Within the tested conditions, 600 °C was the best-performing sintering condition among the temperatures examined for this coating system. Full article

Since their discovery in 2009, perovskite solar cells (PSCs) have demonstrated rapid progress. Ambient-processed, carbon-based PSCs utilizing a pre-heating step offer a cost-effective fabrication route. Nevertheless, the role of the compact titanium dioxide (TiO₂-c) layer in ambient conditions has remained under-explored and inconsistently reported in the literature. This study then investigated the impact of TiO₂-c layer thickness, ranging from 70 nm to 155 nm, on the performance of PSCs fabricated entirely in ambient air with high relative humidity (RH > 70%). The layers were deposited via the sol-gel spin-coating method. Experimental results then revealed that the thinnest layer (70 nm) yielded the lowest average power conversion efficiency (PCE) of 2.05% due to diminished J_sc and V_oc values. The optimized TiO₂-c thickness was also identified at 95 nm, achieving an average PCE of 2.95% and a peak efficiency of 4.5%. Structural analysis via XRD confirmed the presence of both anatase and brookite phases. Notably, increasing the thickness from 70 nm to 155 nm resulted in a slight reduction in the anatase peak and a corresponding increase in the brookite peak. The superior performance at 95 nm could be attributed to a balanced crystal intensity between these two phases. Furthermore, TiO₂-c thickness was found to correlate with larger aggregate formation, better uniform shape grains, and reduced surface roughness, significantly influencing the morphology of the subsequent mesoporous TiO₂-m layer. These findings then provided critical insights into how thickness variation in the TiO₂-c layer could influence the performance of ambient-processed carbon-based PSCs. Full article

Environmental contamination by persistent industrial dyes such as Amido Black demands highly efficient photocatalysts for advanced water treatment. Structural, chemical, and optical strategies based on TiO₂ nanotube engineering are widely explored for this purpose. In this work, highly ordered TiO₂ nanotube arrays were fabricated by electrochemical anodization and subsequently decorated with Pd nanoparticles via potentiostatic electrodeposition (10–300 s), enabling precise control of Pd nanoparticle size and loading. The resulting materials were systematically characterized by SEM, TEM, XRD, XPS, UV–vis DRS, and PL spectroscopy, and their properties were correlated with the photocatalytic degradation of Amido Black under both UV and visible light irradiation. The study reveals a clear size-dependent duality in the role of Pd. For intermediate Pd nanoparticles (≈9 nm, 20 s), Pd behaves predominantly as an electron sink, forming an efficient Schottky junction with anatase TiO₂ that markedly suppresses charge carrier recombination. This configuration yields ≈ 97% Amido Black removal after 120 min of UV irradiation, with an apparent rate constant about three times higher than that of bare TiO₂ nanotubes. In contrast, for ultra-small Pd nanoparticles (≈6 nm, 10 s), interfacial defect states sensitize TiO₂ to visible light, enabling ≈ 65% degradation after 270 min and a rate constant roughly four times higher than that of undecorated nanotubes under visible illumination. At long deposition times (≥150 s), Pd agglomeration leads to enhanced photoluminescence and markedly reduced photocatalytic activity, indicating increased recombination and less effective utilization of photogenerated charges. This provides a practical design rule to rationally tailor Pd–TiO₂ nanotube photocatalysts for targeted UV or visible light applications in dye removal and broader environmental remediation scenarios Full article

With the growing demand for advanced passive cooling technologies in fields such as building energy efficiency, thermal protection of electronic devices, and personal thermal comfort, radiative cooling materials have garnered considerable attention due to their ability to achieve cooling without external energy input. In this study, TiO₂ hollow microspheres with a core–shell structure were successfully synthesized via a solvothermal method using TiCl₄ as the titanium source and (NH₄)₂SO₄ and CO(NH₂)₂ as structure-directing agents. The effects of reaction temperature (120–200 °C) and reaction time (0.5–36 h) on the morphology, crystal phase, specific surface area, pore structure, and infrared optical properties of the microspheres were systematically investigated. The results indicate that all prepared samples consisted of anatase-phase TiO₂, with the microstructure significantly influenced by the synthesis conditions. An increase in reaction temperature promoted the transition from solid to hollow structures; the microspheres exhibited the most regular morphology and the largest specific surface area at 180 °C. Prolonging the reaction time facilitated the Ostwald ripening process, leading to a more complete hollow structure at 24 h. Infrared optical performance analysis revealed that all samples exhibited high emissivity approaching 100% in the 8–15 μm wavelength range, attributed to the intrinsic lattice vibration absorption of TiO₂. In the 3–8 μm range, however, the emissivity was strongly modulated by the microstructure. Samples synthesized at 180 °C for 12–24 h demonstrated stable emissivity characteristics owing to their dense shells, uniform particle size, and well-defined hollow structures. This study elucidates the intrinsic relationship between microstructural evolution and infrared emission performance in TiO₂ hollow microspheres, providing a theoretical foundation and process optimization strategy for their application in radiative cooling coatings, device thermal protection, and personal thermal management textiles. Full article

Titanium dioxide (TiO₂) is a versatile material that exhibits a high refractive index, strong light-scattering capability, effective UV-absorption, wide band gap semiconductor behavior (3.0–3.2 eV), and excellent chemical stability. Owing to this unique combination of properties, TiO₂ is widely used in applications such as cosmetic and healthcare products, architectural and automotive coatings, and photocatalytic degradation of environmental pollutants. In photocatalytic applications, the crystal structure, phase composition and electronic properties of TiO₂ play a critical role in determining its performance. In the present study, TiO₂ nanotubes were synthesized by anodization of Ti° coatings deposited via a semi-industrial arc-PVD process. A post-anodization heat treatment was carried out at 430 °C for 1 h to promote the formation of the anatase phase within the TiO₂ nanotube structures. The structural characterization of the synthesized film was performed using X-ray diffraction (XRD) and Rietveld refinement. This methodology enabled the identification of the formed oxide phases, structure, and crystalline, confirming the formation of mixed oxides in the coating. To address the difficulty of refinement of these crystalline phases, the Le Bail method was applied. This refinement strategy allowed the identification of the crystalline phases that are present in the Ti_xO_y coating, including a hexagonal structure characteristic of α-Ti (space group P63/mmc, No. 194), the tetragonal anatase TiO₂ (space group I41/amd, No. 141) phase, and the trigonal Ti₂O₃ phase (space group R-3/c No. 167). Key crystallographic parameters such as lattice constants, bond lengths and angles, crystallite sizes, unit cell distortion and electron density were systematically evaluated for each phase. In addition, the Wyckoff positions and interatomic distances of the constitutive atoms were calculated, providing a comprehensive description of the TiO₂+Ti₂O₃/Ti° crystallographic system. The topographic and surface oxidation states were recorded by using profilometry and X-ray photoelectron spectroscopy, respectively. Full article

Simultaneous hydrogen fuel and value-added chemical production from renewable resources is a key strategy in sustainable catalysis. This work presents a novel strategy employing metal–organic frameworks (MOFs) as precursors for synthesizing advanced titanium dioxide (TiO₂) photocatalysts with enhanced structural and optical properties. Two photocatalysts, M-BDC and M-2,5PDC, were synthesized via controlled calcination of MIL-125(Ti) using terephthalic and 2,5-pyridinedicarboxylic acids, respectively. Characterization confirmed the formation of mixed anatase/rutile TiO₂ phases with mesoporous structures. Notably, nitrogen incorporation in M-2,5PDC reduced the optical band gap to 2.94 eV compared with 3.08 eV for M-BDC, enhancing visible-light absorption. Photocatalytic experiments conducted at near-neutral pH (6.0) demonstrated effective simultaneous glycerol oxidation and hydrogen evolution without the use of alkaline additives. M-BDC achieved 30% glycerol conversion with 78.85% selectivity toward dihydroxyacetone and 21.15% toward glyceraldehyde, while M-2,5PDC exhibited selectivities of 71.55% and 28.45%, respectively. Glycerol underwent partial oxidation without complete mineralization, generating high-value products in parallel with hydrogen production. Both catalysts displayed excellent reuse stability across three consecutive cycles, with M-BDC showing enhanced dihydroxyacetone selectivity (78.85% to 84.42% between cycles). This MOF-derived TiO₂ platform integrates controlled synthesis, near-neutral pH operation, high selectivity, and catalytic stability, thereby establishing a viable strategy for the simultaneous production of clean fuel and value-added chemicals from renewable resources. Full article

This study presents the development of a low-cost H₂ gas sensor made from a titanium dioxide–zinc oxide composite by means of a simple, cost-effective screen-printing method. The sensing material was created by mixing titanium dioxide and zinc oxide nanoparticles with an organic binder, which was screen-printed onto a glass substrate containing silver electrodes. These samples were then characterized using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The XRD results confirmed that the films boasted well-defined crystallinity, with predominant anatase and hexagonal ZnO phases, as well as uniformity of grains. Sensor performance was evaluated in a custom-built chamber at hydrogen concentrations of 100 to 1000 ppm and at operating temperatures of 100 °C, 200 °C, and 300 °C. The results indicate improved sensor performance as the operating temperature increased to 300 °C, with the best sensitivity values of 0.99, 1.17, and 1.31 at hydrogen concentrations of 100, 500, and 1000 ppm, respectively. The sensor showed stable and reproducible response characteristics, and its responses were retimed after a few hundred seconds. Low-cost fabrication, ease of processing, and reliable sensor performance make titanium oxide–zinc oxide composites promising candidates for hydrogen detection. Full article

To mitigate the intrinsic high corrosion susceptibility of AZ31B magnesium alloy, a three-step synergistic surface modification strategy was developed in this work: initially, a MgO ceramic coating was in situ fabricated on the AZ31B substrate via micro-arc oxidation (MAO); subsequently, a TiO₂ sealing barrier layer was deposited on the MAO coating through a deep ultraviolet (DUV)-assisted sol–gel method; finally, a superhydrophobic top layer was constructed via fluoroalkylsilane (FAS) self-assembly. The microstructural characteristics, chemical compositions and corrosion resistance of the coatings at different modification stages were comprehensively characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water contact angle (WCA) measurements and electrochemical tests. The results showed that the as-deposited TiO₂ was predominantly anatase phase, and FAS molecules were firmly anchored on the coating surface via Si-O-Ti covalent bonds, endowing the composite coating with a WCA of up to 160°. Electrochemical tests demonstrated that the FAS-TiO₂-MAO composite coating exhibited an ultra-low corrosion current density of 1.31 × 10⁻⁹ A/cm² and a remarkably high charge transfer resistance (R_ct) of 3.46 × 10⁸ Ω·cm². Compared with the bare AZ31B substrate, the corrosion current density was decreased by nearly four orders of magnitude, while the charge transfer resistance was enhanced by approximately six orders of magnitude, indicating a significant improvement in corrosion resistance. Moreover, the composite coating exhibited excellent interfacial adhesion, favorable mechanical durability, and outstanding chemical stability, confirming its reliable long-term corrosion protection and high practical application potential. This work provides a feasible strategy for fabricating high-performance superhydrophobic anticorrosive coatings on magnesium alloys. Full article

The persistence of water-soluble polymers such as polyvinylpyrrolidone (PVP) in aquatic environments presents a major challenge for conventional wastewater treatment. Herein, a sunlight-active TiO₂/activated carbon (TiO₂/AC) composite fabricated via a simple physical mixing route is reported for the synergistic adsorption and photocatalytic mineralization of PVP K30. The optimal composite (2:1 weight ratio) exhibits a high surface area (412 m² g⁻¹) and an integrated anatase–carbon architecture. The process operates through a sequential “adsorb-and-shuttle” mechanism, whereby PVP is first concentrated on the composite in the dark (30.2% removal in 8 h) and subsequently degraded under solar irradiation. This dual function leads to 86.4% PVP removal and 72.1% total organic carbon (TOC) mineralization, demonstrating true polymer destruction rather than mere surface accumulation. The composite demonstrates robust performance in simulated wastewater, retaining over 68% PVP removal and 55% TOC mineralization in a complex matrix containing competing inorganic ions and natural organic matter. Spectroscopic and thermogravimetric analyses confirm PVP chain scission and near-complete removal of adsorbed residues. An optimized ethanol-washing protocol enables effective catalyst regeneration, with the composite retaining 85% of its initial activity after five cycles. A detailed techno-economic analysis confirms the economic viability of this regeneration strategy at industrial scales (>1000 kg/year), projecting cost savings exceeding 60% compared to fresh catalyst use. Importantly, the PVP-loaded spent TiO₂–AC was successfully repurposed as an electrocatalyst for the urea oxidation reaction, achieving a high current density of 163.7 mA cm⁻², which surpasses the performance of the pristine composite. The greenness of the overall process was validated using analytical eco-scale (ESA), method volume intensity (AMVI), and white analytical chemistry (WAC) metrics. Overall, this work presents a sustainable, solar-driven platform that advances a circular economy model, integrating effective polymer wastewater remediation with subsequent energy valorization of the spent material. Full article

The success of titanium dental implants rely on osseointegration, influenced by surface properties and early immune responses. While sandblasted and acid-etched (SLA) titanium surfaces have shown clinical success, macrophage-mediated immune responses at these interfaces remain poorly understood. Anatase nanostructures have been shown to influence macrophage polarization on smooth titanium, but their effects on micro-rough SLA surfaces are not fully explored. This study investigates the immunomodulatory effects of micro-nanostructured anatase coatings on SLA titanium using human monocyte-derived macrophages (MDMs). M0-MDMs, were cultured and polarized to M1 and M2- macrophages on Ti-machined, Ti-SLA, Ti-SLA-anatase, and coverslip control surfaces for 48 h. Macrophage behavior was assessed using CCK-8 assay, confocal microscopy, SEM, ELISA, and qRT-PCR. All surfaces demonstrated excellent cytocompatibility, with similar macrophage viability across all investigated groups. M1 macrophages showed upregulation of CCR7 and TNF-α, while M2 macrophages expressed CD209 and CCL13 across all surfaces. Importantly, Ti-SLA-anatase did not significantly alter M1 or M2 markers, cytokine secretion, or gene expression, and did not exacerbate inflammatory responses. Micro-nanostructured anatase coatings on SLA titanium are immunologically well-tolerated and do not increase inflammation. These findings, combined with previously reported enhanced osteogenic properties, suggest the clinical potential of anatase-coated SLA surfaces. Full article