Search Results (127)

Current work investigates the fabrication and performance of nanocomposite membranes, modified with varying concentrations of hybrid nanostructures comprising titanium nanowires coated with iron nanoparticles (TiO₂ NWs-Fe₂O₃), for the removal of Naphthol Blue Black (NBB) dye from industrial wastewater. A series of analytical tools were employed to confirm the successful modification including scanning electron microscopy and EDX analysis, porosity and hydrophilicity measurements, Fourier-transform infrared spectroscopy, and X-Ray Diffraction. The incorporation of TiO₂ NWs-Fe₂O₃ has enhanced membrane performance significantly by increasing the PWF and improving dye retention rates of nanocomposite membranes. At 0.7 g of nanostructure content, the modified membrane (M8) achieved a PWF of 93 L/m²·h and NBB dye rejection of over 98%. The flux recovery ratio (FRR) analysis disclosed improved antifouling properties, with the M8 membrane demonstrating a 73.4% FRR. This study confirms the potential of TiO₂ NWs-Fe₂O₃-modified membranes in enhancing water treatment processes, offering a promising solution for industrial wastewater treatment. These outstanding results highlight the potential of the novel PES-TiO₂ NWs-Fe₂O₃ membranes for dye removal and present adequate guidance for the modification of membrane physical properties in the field of wastewater treatment. Full article

This study presents the development of a TiO₂ nanowire-based electrochemical sensor for the selective and sensitive detection of hydrogen peroxide (H₂O₂) under neutral pH conditions, with a particular focus on its application in analyzing plant stress. The sensor exhibited a linear detection range of 0–0.5 mM, a sensitivity of 0.0393 mA · mM⁻¹, and a detection limit of 2.8 μM in phosphate-buffered saline solution (PBS, pH 7.4). This work’s main novelty lies in the systematic investigation of the relationship between TiO₂ nanostructure morphology, which is controlled by hydrothermal synthesis parameters, and the resulting sensor performance. Interference studies confirmed excellent selectivity in the presence of common electroactive species found in plant samples, such as NaCl, KNO₃, glucose, citric acid, and ascorbic acid. Real sample analysis using barley plant extracts grown under salt stress and treated with Fe₃O₄ nanoparticles confirmed the sensor’s applicability in complex biological matrices, enabling accurate quantification of endogenously produced H₂O₂. Endogenous H₂O₂ concentrations were found to range from near-zero levels in control and Fe₃O₄-only treated plants, to elevated levels of up to 0.36 mM in salt-stressed samples. These levels decreased to 0.25 and 0.15 mM upon Fe₃O₄ nanoparticle treatment, indicating a dose-dependent mitigation of stress. This finding was supported by genome template stability (GTS) analysis, which revealed improved DNA integrity in Fe₃O₄-treated plants. This study takes an integrated approach, combining the development of a nanostructured sensor with physiological and molecular stress assessment. The urgent need for tools to detect stress at an early stage and manage oxidative stress in sustainable agriculture underscores its relevance. Full article

To meet the stringent demands of next-generation flexible optoelectronic devices, a novel fabrication approach is employed that integrates the spray-coating of copper nanowires (Cu NWs) with the magnetron sputtering of SrTiO₃ thin films, thereby yielding SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films. The incorporation of the SrTiO₃ layers results in improved optical performance, with the transmittance of the Cu NW network increasing from 83.5% to 84.2% and a concurrent reduction in sheet resistance from 16.9 Ω/sq to 14.5 Ω/sq. Moreover, after subjecting the hybrid thin films to 100 repeated tape-peeling tests and 2000 bending cycles with a bending radius of 5.0 mm, the resistance remains essentially unchanged, which underscores the films’ exceptional mechanical flexibility and robust adhesion. Additionally, the hybrid thin films are subjected to rigorous high-temperature, high-humidity, and oxidative conditions, where the resistance exhibits outstanding stability. These results substantiate the potential of the SrTiO₃/Cu NWs/SrTiO₃ hybrid thin films for integration into flexible and wearable electronic devices, delivering enhanced optoelectronic performance and long-term reliability under demanding conditions. Full article

Methylene blue (MB), a widely used industrial dye, is a persistent pollutant with documented toxicity to aquatic organisms and potential health risks to humans, even at ultra-trace levels. Conventional monitoring techniques such as UV–Vis spectroscopy and fluorescence emission suffer from limited sensitivity, typically failing to detect MB below ~10⁻⁷ M. In this study, we introduce a surface-enhanced Raman spectroscopy (SERS) platform based on silver nanowire (AgNW) substrates that enables MB detection over an unprecedented dynamic range—from 1.5 × 10⁻⁴ M down to 1.5 × 10⁻¹⁶ M. Raman mapping confirmed the presence of individual signal hot spots at the lowest concentration, consistent with the theoretical number of analyte molecules in the probed area, thereby demonstrating near-single-molecule detection capability. The calculated enhancement factors reached up to 1.90 × 10¹², among the highest reported for SERS-based detection platforms. A semi-quantitative calibration curve was established spanning twelve orders of magnitude, and this platform was successfully applied to monitor MB degradation during two advanced oxidation processes (AOPs): TiO₂ nanotube-mediated photocatalysis under UV irradiation and atmospheric-pressure dielectric barrier discharge (DBD) plasma treatment. While UV–Vis and fluorescence techniques rapidly lost sensitivity during the degradation process, the SERS platform continued to detect the characteristic MB Raman peak at ~1626 cm⁻¹ throughout the entire treatment duration. These persistent SERS signals revealed the presence of residual MB or partially degraded aromatic intermediates that remained undetectable by conventional optical methods. The results underscore the ability of AgNW-based SERS to provide ultra-sensitive, molecular-level insights into pollutant transformation pathways, enabling time-resolved tracking of degradation kinetics and validating treatment efficiency. This work highlights the importance of integrating SERS with AOPs as a powerful complementary strategy for advanced environmental monitoring and water purification technologies. By delivering an ultra-sensitive, low-cost sensor (<USD 0.16 per test) and promoting reagent-free treatment methods, this study directly advances SDG 6 (Clean Water and Sanitation) and SDG 12 (Responsible Consumption and Production). Full article

Deployment of photocatalysis for water disinfection necessitates engineering the process kinetics and achieving the complete recovery of the photocatalyst following the remediation of water. The recovery of the photocatalysts, especially nanostructured photocatalysts, remains a challenge, as indicated by a previous study by our group where only 57% of TiO₂ nanowires were recovered by gravity-assisted settling and sedimentation from water after its photocatalysis-assisted E. coli inactivation. To overcome this challenge, a novel method involving the use of photocatalysts in the form of porous foams is developed and presented. Use of TiO₂ nanowire foams led to a 2–3-log reduction of E. coli in a span of 180 min when ultraviolet-A (UV-A) light was employed for photoactivation, similar to that observed previously by our group. More importantly, the photocatalyst foams were easily recoverable from water via mechanical separation using tweezers, which in this study led to a recovery of 98–99% of the TiO₂ nanowire photocatalysts. This strategy allows for further optimization of both the process kinetics and the total amount of photocatalysts needed for water remediation through optimization of the porosities and the geometries of the foams and ensuring that all the photocatalyst surfaces remain accessible to both the pollutants and light. Full article

In this work, WO₃/TiO₂ core–shell (C-S) nanowires (NWs) were successfully synthesized by the coaxial electrospinning method and subsequent high-temperature calcination treatment. After some microscopic structural characterizations, although the prepared WO₃–TiO₂ and TiO₂–WO₃ C-S NWs displayed quite different surface morphologies, both of the shell coatings were uniform and their typical shell thicknesses were extremely close, with mean values of 22 and 20 nm, respectively. In gas sensing tests, WO₃/TiO₂ C-S NWs exhibited good selectivity towards triethylamine (TEA) without significant interfering gases. Compared with bare WO₃ and TiO₂ NWs, WO₃/TiO₂ C-S NWs showed better gas sensing performance. Specifically, the optimal operating temperature and response of TiO₂–WO₃ C-S NWs to 100 ppm TEA were 130 °C and 106, which were reduced by 70 °C and increased by 5.73 times compared to bare WO₃, respectively. Obviously, the C-S nanostructures contributed to improving the gas sensing performance of materials towards TEA. Finally, some hypothetical sensing mechanisms were proposed, which were expected to have important reference significance for the design of target products applied to TEA sensing. Full article

The development of state-of-the-art gas sensors based on metal oxide semiconductors (MOS) to monitor hazardous and greenhouse gas (e.g., methane, CH₄, and carbon dioxide, CO₂) has been significantly advanced. Moreover, the morphological and topographical structures of MOSs have significantly influenced the gas sensors by means of surface catalytic activities. This work examines the impact of morphological and topological networked assembly of zinc oxide (ZnO) nanostructures, including microparticles and nanoparticles (0D), nanowires and nanorods (1D), nanodisks (2D), and hierarchical networks of tetrapods (3D). Gas sensors consisting of vertically aligned ZnO nanorods (ZnO–NR) and topologically interconnected tetrapods (T–ZnO) of varying diameter and arm thickness synthesized using aqueous phase deposition and flame transport method on interdigitated Pt electrodes are evaluated for methane detection. Smaller-diameter nanorods and tetrapod arms (nanowire-like), having higher surface-to-volume ratios with reasonable porosity, exhibit improved sensing behavior. Interestingly, when the nanorods’ diameter and interconnected tetrapod arm thickness were comparable to the width of the depletion layer, a significant increase in sensitivity (from 2 to 30) and reduction in response/recovery time (from 58 s to 5.9 s) resulted, ascribed to rapid desorption of analyte species. Additionally, nanoparticles surface-catalyzed with Pd (~50 nm) accelerated gas sensing and lowered operating temperature (from 200 °C to 50 °C) when combined with UV photoactivation. We modeled the experimental findings using a modified general formula for ZnO methane sensors derived from the catalytic chemical reaction between methane molecules and oxygen ions and considered the structural surface-to-volume ratios (S/V) and electronic depletion region width (L_d) applicable to other gas sensors (e.g., SnO₂, TiO₂, MoO₃, and WO₃). Finally, the effects of UV light excitation reducing detection temperature help to break through the bottleneck of ZnO-based materials as energy-saving chemiresistors and promote applications relevant to environmental and industrial harmful gas detection. Full article

This study investigated a hybrid electrode based on titanium/titanium dioxide nanowires/reduced graphene oxide (Ti-TiO₂(NW)/rGO) that was developed in two stages. The Ti-TiO₂(NW)/rGO was obtained by hydrothermal treatment in a mixed solution of H₂O₂ and melamine for Ti-TiO₂ support, followed by a simple spin-coating deposition method and thermal oxidation in a controlled atmosphere of nitrogen gas (99%). The as-prepared structures of electrodes were characterized using ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). In addition, the electrochemical behavior was assessed by cyclic voltammetry (CV) in a 1M HNO₃-supporting electrolyte and in the presence of 4 mM K₄Fe(CN)₆ 3H₂O to determine the electroactive surface area and apparent diffusion coefficient of the hybrid electrode. The development of the Ti-TiO₂(NW)/rGO hybrid electrode provides a sensitive method for photo-electrooxidation of doxorubicin due to exploiting the synergistic and remarkable properties of the nanowires of TiO₂ and of reduced graphene oxide (rGO) layer on the electrode surface. Full article

The photocatalytic oxidative coupling of methane (OCM) on metal-loaded one-dimensional TiO₂ nanowires (TiO₂ NWs) was performed. With metal loading, the electric and optical properties of TiO₂ NWs were adjusted, contributing to the improvement of the activity and selectivity of the OCM reaction. In the photocatalytic OCM reaction, the 1.0 Au/TiO₂ NW catalyst exhibits an outstanding C₂H₆ production rate (4901 μmol g⁻¹ h⁻¹) and selectivity (70%), alongside the minor production of C₃H₈ and C₂H₄, achieving a total C₂–C₃ hydrocarbon selectivity of 75%. In contrast, catalysts loaded with Ag, Pd, and Pt show significantly lower activity, with Pt/TiO₂ NWs producing only CO₂, indicating a propensity for the deep oxidation of methane. The O₂-TPD analyses reveal that Au facilitates mild O₂ adsorption and activation, whereas Pt triggers excessive oxidation. Spectroscopic and kinetic studies demonstrate that Au loading not only enhances the separation efficiency of photogenerated electron–hole pairs, but also promotes the generation of active oxygen species in moderate amounts, which facilitates the formation of methyl radicals and their coupling into C₂H₆ while suppressing over-oxidation to CO₂. This work provides novel insights and design strategies for developing efficient photocatalysts. Full article

Zinc oxide and titanium dioxide are materials with strong photocatalytic and antimicrobial activity. This activity is greater when the material is in nanocrystalline form. It has been seen that these properties are also present in the ZnO-TiO₂ nanocomposite material, and the extent depends on multiple factors, such as crystallinity, structural composition, crystallite size, and morphology. These structural properties can be varied by acting on the synthesis of the material, obtaining a wide variety of composites: random nanoparticles, nanorods, nanowires, nanotubes, nanofibers, tetrapods, core–shell, hollow spheres, inverse opal structures (IOSs), hierarchical structures, and films. When an interface between nanocrystallites of the two oxides is created, the composite system manages to have photocatalytic activity greater than that of the two separate oxides, and in certain circumstances, even greater than P25. The antimicrobial activity results also improved for the composite system compared to the two separate oxides. These two aspects make these materials interesting in various fields, such as wastewater and air treatment, energy devices, solar filters, and pharmaceutical products and in the context of the restoration of monumental cultural assets, in which their use has a preventive purpose in the formation of biofilms. In this review we analyse the synthesis techniques of ZnO-TiO₂ nanocomposites, correlating them to the shape obtained, as well as the photocatalytic and antimicrobial activity. It is also illustrated how ZnO-TiO₂ nanocomposites can have a less negative impact on toxicity for humans and the environment compared to the more toxic ZnO nanoparticles or ZnO. Full article

Ti⁴⁺-doped V₂O₅ films with nanowires on top and a dense, long nanorod layer on the bottom were successfully fabricated using the spin-coating route. During the electrochromic cycling, charge transfer resistance (R_ct) decreases while ion-diffusion ability (K_Ω) rapidly drops in the first ten cycles and then levels off. Low R_ct and morphology of nanowires collaboratively improved the electrochromic behavior of Ti⁴⁺-doped V₂O₅ films by enhancing the charge transfer speed and minimizing polarization and dissolution. The obtained Ti⁴⁺-doped V₂O₅ film shows better electrochromic properties than the undoped V₂O₅ film, with a coloration efficiency (CE) of 34.15 cm²/C, coloration time of 9.00 s, and cyclic retention of 82.6% at cycle 100. In contrast, the corresponding values for the undoped V₂O₅ film were 23.57 cm²/C, 13.16 s, and 43.6%. Full article

The present study investigates the photocatalytic properties of hydrothermally synthesized TiO₂ nanowires (NWs) for CO₂ reduction in H₂O vapor. It has been demonstrated that TiO₂ NWs, thermally treated at 500–700 °C, demonstrate an almost tenfold higher yield of products compared to the known commercial powder TiO₂ P25. It has been found that the best material is a combination of anatase, TiO₂-B and rutile. The product yield increases with increasing heat treatment temperature of TiO₂ NWs. This is associated with an increase in the degree of crystallinity of the material. It is shown that the best product yield of the CO₂ reduction in H₂O vapor is achieved when the TiO₂ NW photocatalyst is heated to 100 °C. Full article

In this paper, the photocatalytic degradation of methyl orange solution by MnO₂/TiO₂ nanotube arrays (NTAs) with different structure was studied. Initially, bamboo-like TiO₂ NTAs with folded tube walls were synthesized using the anodic oxidation method. Subsequently, MnO₂ nanowires/TiO₂ NTAs and MnO₂ nanoparticles/TiO₂ NTAs were prepared via high-temperature and low-temperature hydrothermal methods, respectively. Photocurrent-time transient tests revealed that MnO₂ nanoparticles/TiO₂ NTAs produced by the low-temperature hydrothermal method exhibited a relatively good photocurrent response. All the deposited MnO₂/TiO₂ bamboo-like nanotube nanocomposites were tested for photocatalytic decomposition under different pH and light conditions. The results showed that MnO₂ could adsorb and degrade methyl orange in the absence of light and acidity, and the degradation degree was proportional to the concentrations of Mn. MnO₂ was stimulated to produce photogenic electrons, which migrated to the surface of the TiO₂ and extended the life of photogenic charge carriers. Full article

Open-cell foams based on hydroxyapatite (HAp) can mimic the extracellular matrix (ECM) to better replace damaged hard tissues and assist in their regeneration processes. Aerogels of HAp nanowires (NW) with barium titanate (BT) particles were produced and characterized regarding their physical and chemical properties, bioactivity, and in vitro cytotoxicity. Considering the role of piezoelectricity (mainly due to collagen) and surface charges in bone remodeling, all BT particles, of size 280 nm and 2 and 3 µm, contained BaTiO₃ in their piezoelectric tetragonal phase. The synthesized nanowires were verified to be AB-type carbonated hydroxyapatite. The aerogels showed high porosity and relatively homogeneous distribution of the BT particles. Barium titanate proved to be non-cytotoxic while all the aerogels produced were cytotoxic for an extract concentration of 1 mg/mL but became non-cytotoxic at concentrations of 0.5 mg/mL and below. It is possible that these results were affected by the higher surface area and quicker dissolution rate of the aerogels. In the bioactivity assays, SEM/EDS, it was not easy to differentiate between the apatite deposition and the surface of the HAp wires. However, a quantitative EDS analysis shows a possible CaP deposition/dissolution cycle taking place. Full article

A multi-step procedure was effectively employed to synthesize innovative three-dimensional (3D) heterostructures encompassing sodium titanate (Na₂Ti₃O₇) nanowire cores, an intermediate resorcinol–formaldehyde (RF) layer, and outer silver (Ag) nanoparticle sheaths, referred to as Na₂Ti₃O₇@RF@Ag heterostructures. Initially, a one-step hydrothermal technique facilitated the direct growth of single-crystal Na₂Ti₃O₇ nanowires onto a flexible Ti foil. Subsequently, a two-step wet chemical process facilitated the sequential deposition of an RF layer and Ag nanoparticles onto the Na₂Ti₃O₇ nanowires at a low reaction temperature. Optimal concentrations of silver nitrate and L-ascorbic acid can lead to the cultivation of Na₂Ti₃O₇@RF@Ag heterostructures exhibiting heightened surface-enhanced Raman scattering (SERS), which is particularly beneficial for the detection of rhodamine B (RhB) molecules. This phenomenon can be ascribed to the distinctive geometry of the Na₂Ti₃O₇@RF@Ag heterostructures, which offer an increased number of hot spots and surface-active sites, thereby showcasing notable SERS enhancement, commendable reproducibility, and enduring stability over the long term. Furthermore, the Na₂Ti₃O₇@RF@Ag heterostructures demonstrate remarkable follow-up as first-order chemical kinetic and recyclable photocatalysts for the photodecomposition of an RhB solution under UV light irradiation. This result can be attributed to the enhanced inhibition of electron–hole pair recombination and increased surface-active sites. Full article