Search Results (350)

This study reports the impact of a silver nanoparticles/reduced graphene oxide@titanium dioxide nanocomposite (Ag/rGO@TiO₂) on the mechanical and biocompatibility properties of poly(styrene-co-methylmethacrylate)/poly methyl methacrylate (PS-PMMA/PMMA)-based bone cement. The chemical, structural, mechanical, and thermal characteristics of Ag/rGO@TiO₂ nanocomposite-reinforced PS-PMMA bone cement ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) were evaluated using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, and electron microscopy. FT-IR, XRD, and transmission electron microscopy results confirmed the successful synthesis of the nanocomposite and the nanocomposite-incorporated bone cement. The elastic modulus (E) and hardness (H) of the ((Ag/rGO@TiO₂)/(PS-PMMA)/PMMA) bone cement were measured to be 5.09 GPa and 0.202 GPa, respectively, compared to the commercial counterparts, which exhibited E and H values of 1.7 GPa to 3.7 GPa and 0.174 GPa, respectively. Incorporating Ag/rGO@TiO₂ nanocomposites significantly enhanced the thermal properties of the bone cement. Additionally, in vitro studies demonstrated that the bone cement was non-toxic to the MG63 cell line. Full article

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article

The oxygen-evolving IrO₂-Ta₂O₅/Ti anode (OEA), primarily used in electrolyzers for plating, metal powder production, electrowinning (EW), and water electrolysis, is analyzed. This study focuses on the distribution of oxygen evolution reaction (OER) activity and the associated operational loss over the randomized OEA texture. The OER activity and its distribution across the IrO₂-Ta₂O₅ coating surface are key factors that influence EW operational challenges and the lifecycle of OEA in EW processes. To understand the OER activity distribution over the coating’s randomized texture, we performed analyses using anode polarization in acid solution at both low and high (EW operation relevant) overpotentials and electrochemical impedance spectroscopy (EIS) during the OER. These measurements were conducted on anodes in both their as-prepared and deactivated states. The as-prepared anode was deactivated using an accelerated stability test in an acid solution, the EW simulating electrolyte. The obtained data are correlated with fundamental electrochemical properties of OEA, such as structure-related pseudocapacitive responses at open circuit potential in the same operating environment. OER and Ir dissolution kinetics, along with the physicochemical anode state upon deactivation, are clearly characterized based on current and potential dependent charge transfer resistances and associated double layer capacitances obtained by EIS. This approach presents a useful tool for elucidating, and consequently tailoring and predicting, anode OER activity and electrolytic operational stability in industrial electrochemical applications. Full article

Ru/TiO₂ catalysts are well known for their high activity in the hydrogenation of CO₂ to CH₄ (the Sabatier reaction). This activity is commonly attributed to strong metal–support interactions (SMSIs), associated with reducible oxide layers partly covering the Ru-metal particles. Moreover, isothermal rates of formation of CH₄ can be significantly enhanced by the exposure of Ru/TiO₂ to light of UV/visible wavelengths, even at relatively low intensities. In this study, we confirm the significant enhancement in the rate of formation of methane in the conversion of CO₂, e.g., at 200 °C from ~1.2 mol g_Ru⁻¹·h⁻¹ to ~1.8 mol g_Ru⁻¹·h⁻¹ by UV/Vis illumination of a hydrogen-treated Ru/TiO_x catalyst. The activation energy does not change upon illumination—the rate enhancement coincides with a temperature increase of approximately 10 °C in steady state (flow) conditions. In-situ DRIFT experiments, performed in batch mode, demonstrate that the Ru–CO absorption frequency is shifted and the intensity reduced by combined UV/Vis illumination in the temperature range of 200–350 °C, which is more significant than can be explained by temperature enhancement alone. Moreover, exposing the catalyst to either UV (predominantly exciting TiO₂) or visible illumination (exclusively exciting Ru) at small intensities leads to very similar effects on Ru–CO IR intensities, formed in situ by exposure to CO₂. This further confirms that the temperature increase is likely not the only explanation for the enhancement in the reaction rates. Rather, as corroborated by photophysical studies reported in the literature, we propose that illumination induces changes in the electron density of Ru partly covered by a thin layer of TiO_x, lowering the CO coverage, and thus enhancing the methane formation rate upon illumination. Full article

In this study, TiO₂-Fe₂O₃/polyvinylpyrrolidone (PVP) hybrids were prepared using the sol–gel method. The iron content in the synthesized samples was 10 and 20 wt%. The influence of PVP on the phase transformation, morphology and optical properties of the as-prepared hybrids was characterized by various physicochemical methods—XRD analysis, UV–Vis spectroscopy, IR spectroscopy and SEM. The obtained sol–gel powders were tested for photocatalytic activity against tetracycline hydrochloride in distilled water under ultraviolet and simulated solar light illumination. The obtained results were compared to commercial TiO₂ P25 (Evonik). The investigated samples exhibited good photocatalytic efficiency for the degradation of tetracycline hydrochloride; however, better activity was demonstrated by the 90TiO₂-10Fe₂O₃/PVP sample. The latter one displayed weak antibacterial action against E. coli ATCC 25922 in the presence of UVA light. Full article

This study pioneers the development of a synergistic Ag-doped molecularly imprinted TiO₂ photocatalyst (MIP-Ag-TiO₂) through a multi-strategy engineering approach, integrating molecular imprinting technology with plasmonic metal modification via a precisely optimized sol–gel protocol. Breaking from conventional non-selective photocatalysts, our material features an engineered surface architecture that combines selective molecular recognition sites with enhanced charge separation capabilities, specifically tailored for the targeted degradation of recalcitrant salicylic acid (SA) contaminants. Advanced characterization (XRD, EPR, FT-IR, TEM-EDS) reveals unprecedented structure–activity relationships, demonstrating how template molecule ratios (Ti:SA = 5:1) and calcination parameters (550 °C) collaboratively optimize both adsorption selectivity and quantum efficiency. The optimized MIP-Ag-TiO₂ achieves breakthrough performance metrics: 98.6% SA degradation efficiency at 1% Ag doping, coupled with a record selectivity coefficient R = 7.128. Mechanistic studies employing radical trapping experiments identify a dual •OH/O_2⁻-mediated degradation pathway enabled by the Ag-TiO₂ Schottky junction. This work establishes a paradigm-shifting “capture-and-destroy” photocatalytic system that simultaneously addresses the critical challenges of selectivity and quantum yield limitations in advanced oxidation processes, positioning molecularly imprinted plasmonic photocatalysts as next-generation smart materials for precision water purification. Full article

As a rarefied metallic element, strontium (Sr) is susceptible to significant environmental radioactive contamination risks during industrial mining and refining processes. In this study, NaA molecular sieves were prepared by alkali excitation using synthetic powders, which were homogeneously blended with the polyacrylonitrile (PAN) matrix, and nanoscale TiO₂ reinforcing phases were introduced. Finally, composite separation membranes (TiO₂-NaA@PANMs) with stable adsorption properties were constructed by electrostatic spinning technology. The micro-morphology and interfacial properties were characterized by SEM, XRD, and FT-IR systems. The adsorption experiments demonstrated that the equilibrium adsorption capacity of the system for Sr²⁺ reached 55.00 mg/g at the optimized pH = 6.0, and the theoretical saturated adsorption capacity at 298 K was 80.89 mg/g. The isothermal process conformed to the Langmuir’s model of monomolecular layer adsorption, and the kinetic behavior followed the quasi-secondary kinetic equation. Following three cycles of regeneration by elution with a 0.3 mol/L sodium citrate solution, the membrane material exhibited 81.60% Sr²⁺ removal efficacy. The composite membrane passages exhibited remarkable potential for utilization in engineering applications involving the treatment of complex nuclear wastewater. Full article

Producing hydrogen by water electrolysis has attracted significant attention as a potential renewable energy solution. In this work, a catalyst with reduced graphene oxide (rGO) loaded on IrO₂/TiO₂ (called rGO/IrO₂/TiO₂) was designed for the catalytic oxygen evolution reaction (OER). The catalyst was synthesized by coating graphene oxide onto a pretreated IrO₂/TiO₂ precursor, followed by thermal treatment at 450 °C to achieve reduction and the adhesion of graphene to the substrate. The graphene support retained its intact sp² carbon framework with minor oxygen-containing functional groups, which enhanced electrical conductivity and hydrophilicity. Benefiting from the synergistic effect of an rGO, IrO₂, and TiO₂ matrix, the rGO/IrO₂/TiO₂ catalyst only needed overpotentials of 240 mV and 320 mV to reach 10 mA cm⁻² and 100 mA cm⁻² in the OER, along with excellent stability over 50 h. Its morphology and crystalline structure were characterized by SEM and XRD spectroscopy, and its electrochemical performance was tested by LSV analysis, EIS impedance spectrum, and double-layer capacitance (C_dl) measurements. This work introduces an innovative and eco-friendly strategy for constructing a high-performance, functionalized Ir-based catalyst. Full article

The aim of this study is to investigate the impact of the rotation speed of ball milling on the CO₂ reduction performance of P₄O₁₀/TiO₂. The rotation speeds studied were 600 rpm, 400 rpm and 200 rpm. It is revealed that the particle size of P₄O₁₀ within P₄O₁₀/TiO₂ prepared at the rotation speed of 600 rpm was the smallest among the investigated rotation speeds. It is revealed that the concentration of formed CO, as well as the molar quantity of CO per unit weight of photocatalyst P₄O₁₀/TiO₂, prepared at the rotation speed of 600 rpm in the case of CO₂:H₂O = 1:1 was the highest among the different molar ratios irrespective of light illumination condition. In the case of CO₂:H₂O = 1:1 under the light illumination conditions of UV and VIS and IR, VIS and IR, and IR, the following findings were obtained: The molar quantity of CO per unit weight of photocatalyst prepared at 600 rpm was 25.2 μmol/g under the light illumination condition of UV and VIS and IR, which was 20.3% more than that prepared at 400 rpm and 20.6% more than that prepared at 200 rpm. The molar quantity of CO per unit weight of rotation speed of 600 rpm under the light illumination condition of VIS and IR was 18.4 μmol/g, which was 21.3% more than that prepared at 400 rpm and 38.7% more than that prepared at 200 rpm. The molar quantity of CO per unit weight of photocatalyst prepared at 600 rpm was 11.9 μmol/g under the light illumination condition of IR, which was 1.8% more than that prepared at 400 rpm and 8.2% more than that prepared at 200 rpm. Full article

In recent years, domestic research on the ion substitution behavior and chromaticity of the mineral composition of “Ya’an Green” remains insufficient, while there is almost no relevant research on “Ya’an Green” abroad. In this study, X-ray powder diffraction (XRD), electron probe microanalysis (EPMA), infrared spectroscopy (IR), ultraviolet–visible spectroscopy (UV-Vis), and colorimetry were employed. The results indicate that the green and yellow matrices of “Ya’an Green” are primarily composed of muscovite, with rutile also present in the yellow matrix. In contrast, the white–green samples are mainly composed of quartz, with muscovite as a secondary mineral. Additionally, it was observed that the (004) crystal plane of muscovite exhibits a peak shift to lower 2θ angles, attributed to the substitution of Al³⁺ by ions with larger radii, such as Ba²⁺, Cr³⁺, and Fe²⁺, leading to an increase in unit cell parameters and a consequent shift in the peak to lower wavenumbers. The main elements of “Ya’an Green” are Al, Si, and K, with minor elements including Na, Fe, and Cr. Furthermore, Mg²⁺, Ca²⁺, Ti⁴⁺, Cr³⁺, and Fe²⁺ in the samples can substitute for Al³⁺ through isomorphic substitution. The infrared spectrum of muscovite in the ‘Ya’an Green’ sample shows three typical absorption peaks, 422 cm⁻¹ and 513 cm⁻¹ caused by Si-O bending vibration, 697 cm⁻¹ and 837 cm⁻¹ caused by Si-O-Al vibration, 948 cm⁻¹ caused by O-H bending vibration, and 3647 cm⁻¹ caused by O-H stretching vibration. The peak at 837 cm⁻¹ exhibits varying degrees of shift due to the substitution of Al³⁺ by ions with larger radii. The ultraviolet–visible spectra display two broad absorption bands at 422 nm and 615 nm, which are caused by Cr³⁺ transition, indicating that Cr is the chromogenic element responsible for the green color. A correlation was observed between the Cr³⁺ content and the hue angle h in “Ya’an Green” samples: the higher the Cr³⁺ content, the closer the hue angle is to 136^°, resulting in a darker green color, while lower Cr³⁺ content leads to a deviation from the dark green hue. This study establishes for the first time the correlation between the mineral composition of ‘Ya’an Green’ and its chromatic parameters and explores the linear relationship between its color and the number of color-causing elements and elemental substitution, which provide data support and theoretical models for the study of the color of seal stones. Full article

This study develops iridium (Ir)-based catalysts for the hydrogenation of dodecanoic acid, a medium-chain fatty acid abundant in palm kernel and coconut oils, for producing fatty alcohols and alkanes. Among various supports such as AlOOH, SiO₂, TiO₂, Nb₂O₅, MoO₃, Ta₂O₅, ZrO₂, and WO₃ for 7.5 wt% Ir loading, an Ir-impregnated Nb₂O₅ (Ir/Nb₂O₅) catalyst demonstrated remarkable performance with 100% conversion and a high dodecanol yield (89.1%) under mild conditions (170 °C, 4.0 MPa H₂), while at higher temperatures and pressures (200 °C, 8.0 MPa H₂), Ir-impregnated MoO₃ (Ir/MoO₃) produced dodecane as the main product with a yield of 90.7%. These findings can tailor product selectivity toward desired bio-based chemicals and fuels, offering sustainable pathways for fatty acid hydrogenation by optimizing catalyst supports and reaction conditions in the Ir-based catalyst. Full article

The urgency to decarbonize fuels has contributed to a rise in biofuel production, which has culminated in a significant increase in the waste quantity of glycerol produced. Therefore, to convert glycerol waste into high-value products, electrochemical oxidation (EO) is a viable alternative for the co-generation of carboxylic acids, such as formic acid (FA) and green hydrogen (H₂), which are considered energy carriers. The aim of this study is the electroconversion of glycerol into FA by EO using a divided electrochemical cell, driven by a photovoltaic (PV) system, with a dimensionally stable anode (DSA, Ti/TiO₂-RuO₂-IrO₂) electrode as an anode and Ni-Fe stainless steel (SS) mesh as a cathode. To optimize the experimental conditions, studies were carried out evaluating the effects of applied current density (j), electrolyte concentration, electrolysis time, and electrochemical cell configuration (undivided and divided). According to the results, the optimum experimental conditions were achieved at 90 mA cm⁻², 0.1 mol L⁻¹ of Na₂SO₄ as a supporting electrolyte, and 480 min of electrolysis. In this condition, 256.21 and 211.17 mg L⁻¹ of FA were obtained for the undivided and divided cells, respectively, while the co-generation of 6.77 L of dry H₂ was achieved in the divided cell. The electroconversion process under the optimum conditions was also carried out with a real sample, where organic acids like formic and acetic acids were co-produced simultaneously with green H₂. Based on the preliminary economic analysis, the integrated-hybrid process is an economically viable and promising alternative when it is integrated with renewable energy sources such as solar energy. Full article

Flexible polymer-based piezoelectric nanogenerators (PENGs) have gained significant interest due to their ability to deliver clean and sustainable energy for self-powered electronics and wearable devices. Recently, the incorporation of fillers into the ferroelectric polymer matrix has been used to improve the relatively low piezoelectric properties of polymer-based PENGs. In this study, we investigated the effect of various nanofillers such as titania (TiO₂), zinc oxide (ZnO), reduced graphene oxide (rGO), and lead zirconate titanate (PZT) on the PENG performance of the nanocomposite thin films containing the nanofillers in poly(vinylidene fluoride-co-trifluoro ethylene) (P(VDF-TrFE)) matrix. The nanocomposite films were prepared by depositing molecularly thin films of P(VDF-TrFE) and nanofiller nanoparticles (NPs) spread at the air/water interface onto the indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrate, and they were characterized by measuring their microstructures, crystallinity, β-phase contents, and piezoelectric coefficients (d₃₃) using SEM, FT-IR, XRD, and quasi-static meter, respectively. Multiple PENGs incorporating various nanofillers within the polymer matrix were developed by assembling thin film-coated substrates into a sandwich-like structure. Their piezoelectric properties, such as open-circuit output voltage (V_OC) and short-circuit current (I_SC), were analyzed. As a result, the PENG containing 4 wt% PZT, which was named P-PZT-4, showed the best performance of V_OC of 68.5 V with the d₃₃ value of 78.2 pC/N and β-phase content of 97%. The order of the maximum V_OC values for the PENGs of nanocomposite thin films containing various nanofillers was PZT (68.5 V) > rGO (64.0 V) > ZnO (50.9 V) > TiO₂ (48.1 V). When the best optimum PENG was integrated into a simple circuit comprising rectifiers and a capacitor, it demonstrated an excellent two-dimensional power density of 20.6 μW/cm² and an energy storage capacity of 531.4 μJ within 3 min. This piezoelectric performance of PENG with the optimized nanofiller type and content was found to be superior when it was compared with those in the literature. This PENG comprising nanocomposite thin film with optimized nanofiller type and content shows a potential application for a power source for low-powered electronics such as wearable devices. Full article

CDs/TiO₂ nanohybrids were synthesized and tested for photocatalytic H₂ production from aqueous media through simulated solar light-driven photocatalytic reactions. Firstly, three different types of CDs were prepared through green methods, specifically hydrothermal treatment and microwave irradiation, using citric acid and urea as precursors in varying molar ratios. After a multi-step purification procedure, impurity-free CDs were obtained. The as-synthesized CDs were thoroughly characterized using UV-Vis, FT-IR, and PL spectroscopy, along with HR-TEM. The results revealed that the size and optical and physicochemical properties of CDs can be tailored by selecting the precursors’ ratio and the synthetic approach. The heterostructured CDs/TiO₂ photocatalysts were formed solvothermally and were analyzed using UV-Vis/DRS, FT-IR, and XPS techniques, which confirmed the effective incorporation of CDs and the improved properties of TiO₂. The use of sacrificial reagents is among the most common strategies for enhancing H₂ production from water through photocatalytic processes; herein, ethanol was selected as a green liquid organic hydrogen carrier. A maximum H₂ production rate of 0.906 μmol H₂/min was achieved, while the recyclability study demonstrated that the photocatalyst maintained stable performance during multiple cycles of reuse. Thus, optimizing the synthesis conditions of CDs/TiO₂ nanohybrids resulted in the creation of environmentally friendly and reusable photocatalysts. Full article

The present paper deals with the synthesis, characterization, and properties of sol-gel-derived TiO₂/TeO₂/Nb₂O₅ nanopowders. The gels were prepared using a combination of organic [Ti (IV) n-butoxide, Nb (V) ethoxide (C₁₀H₂₅NbO₅)] and inorganic [telluric acid (H₆TeO₆)] precursors. The aging of gels was performed in air for several days in order to enable further hydrolysis. The phase formation of the gels was investigated by XRD upon heating in the temperature range of 200–700 °C. It was established that the gels heat-treated up to 300 °C exhibited a predominantly amorphous phase in all binary and ternary compositions. The amount of amorphous phase gradually decreased with increasing temperature, and the first TiO₂ (anatase) crystals were detected at about 400–500 °C. The average crystallite size of TiO₂ (anatase) in the powdered samples heat-treated at 400 °C was about 10 nm. By DTA, it was established that the decomposition of organics is accompanied by strong weight loss occurring in the temperature range of 200–300 °C. The completeness of the hydrolysis-condensation reactions was verified by IR and UV–Vis analyses. The UV–Vis spectra of the as-prepared gels exhibited red shifting of the cut-off. Photoluminescence spectra exhibited a change in intensity with varying temperature and composition. The performed photocatalytic tests showed that all powders possess photocatalytic activity toward Malachite green organic dye. The obtained nanopowders exhibited good antibacterial properties against E. coli ATCC 25922. The obtained samples can be considered as prospective materials for use as environmental catalysts. Full article