Search Results (27)

Efficient, low-cost catalysts are required for on-demand H₂ generation from chemical hydrides. This study utilized piezoelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers (NFs) as a support to encapsulate bimetallic Co–Mo nanoparticles (NPs) for H₂ production via sodium borohydride (SBH) methanolysis. The PVDF-HFP membranes were synthesized through electrospinning, followed by in situ SBH reduction, which resulted in the uniform dispersion of amorphous Co–Mo NPs within the nanofibrous matrix. The optimized CoMo-0.2@PVDF-HFP membrane exhibited a hydrogen generation rate (HGR) of 1.9 × 10³ mL·min⁻¹·g⁻¹ (Co) at 298 K, indicating a 3.6-fold improvement relative to monometallic Co. Kinetic studies showed a nearly first-order relationship with catalyst dose and a nearly zero-order relationship with respect to SBH concentration, suggesting kinetics controlled by surface saturation. The activation energy (E_a) was determined to be 14.03 kJ·mol⁻¹. Moreover, the catalyst maintained over 80% of its original activity after five cycles. This enhanced performance is attributed to the combined effects of Co and Mo, the amorphous nature of the active sites, and the piezoelectric polarization of PVDF-HFP during mechanical stirring, which together improve charge transfer and reduce NP agglomeration. Full article

A flexible polyionic liquid (PIL) nanofiber membrane-supported phosphomolybdic acid catalyst (PM-PIL) was fabricated via stepwise chemical transformation of polyacrylonitrile (PAN) nanofiber membranes. The nitrile groups of PAN were converted into pyridine units, followed by quaternization and anion exchange with phosphomolybdic acid (PMo), resulting in a polyionic liquid membrane with uniformly immobilized PMo species. Benefiting from its nanofibrous architecture and ionic liquid characteristics, the PM-PIL membrane simultaneously acts as a heterogeneous catalyst and a Pickering emulsion stabilizer, enabling efficient interfacial catalytic oxidation desulfurization. The PM-PIL membrane exhibited excellent catalytic performance toward dibenzothiophene (DBT) oxidation in an H₂O₂-based model oil system. Under optimized conditions (60 °C, O/S = 150:1), more than 90% DBT removal was achieved within 90 min, and complete desulfurization was obtained within 2 h. Compared with phosphomolybdic acid and poly(pyridine), the PM-PIL membrane showed markedly enhanced activity and stability, maintaining over 90% efficiency after six cycles. Product analysis confirmed selective oxidation of DBT to dibenzothiophene sulfone. This work provides a robust and recyclable membrane-based catalytic platform for efficient oxidative desulfurization. Full article

For supported catalysts, the synergistic effect of physicochemical properties (including oxygen storage capacity (OSC), metal–support interaction, dispersion, and reducibility) is crucial for methane partial oxidation (POM). This study aims to prepare Ni-based nanofibrous catalysts using traditional metal oxides (Al₂O₃, ZrO₂, CeO₂, Zr_0.92(Y₂O₃)_0.08O_2−δ, and Ce_0.9Gd_0.1O_2−δ) as supports via electrospinning, and thoroughly investigates the synergistic effect of the catalyst’s physicochemical properties on catalytic performance. For the Ni/Zr_0.92(Y₂O₃)_0.08O_2−δ and Ni/Ce_0.9Gd_0.1O_2−δ catalysts, doping significantly enhances Ni dispersion, reducibility, and OSC, thereby improving catalytic performance. The results demonstrate that the catalytic activity follows the following order: Ni/Ce_0.9Gd_0.1O_2−δ > Ni/CeO₂ > Ni/Zr_0.92(Y₂O₃)_0.08O_2−δ > Ni/ZrO₂ > Ni/Al₂O₃, which is closely associated with the synergistic effect of their physicochemical properties. In addition, this study focuses on elucidating the underlying mechanism by which the Gd³⁺ doping level influences the catalytic performance of the Ni/Ce_0.9Gd_xO_2−δ (x = 0.1, 0.2, 0.3) catalysts. The Ni/Ce_0.9Gd_0.1O_2−δ catalyst exhibits the optimal Ni dispersion, reducibility, and OSC, corresponding to the highest catalytic performance. This re-emphasizes the crucial role of the synergistic effect of the catalyst’s physicochemical properties in determining catalytic performance. Therefore, investigating this synergistic effect is essential for achieving superior catalytic performance. Full article

Filtration of submicron particles and nanoparticles is an important problem in nano-industry and in air conditioning and ventilation systems. The presence of submicron particles comprising fungal spores, bacteria, viruses, microplastic, and tobacco-smoke tar in ambient air is a severe problem in air conditioning systems. Many nanotechnology material processes used for catalyst, solar cells, gas sensors, energy storage devices, anti-corrosion and hydrophobic surface coating, optical glasses, ceramics, nanocomposite membranes, textiles, and cosmetics production also generate various types of nanoparticles, which can retain in a conveying gas released into the atmosphere. Particles in this size range are particularly difficult to remove from the air by conventional methods, e.g., electrostatic precipitators, conventional filters, or cyclones. For these reasons, nanofibrous filters produced by electrospinning were developed to remove fine particles from the post-processing gases. The physical basis of electrospinning used for nanofilters production is an employment of electrical forces to create a tangential stress on the surface of a viscous liquid jet, usually a polymer solution, flowing out from a capillary nozzle. The paper presents results for investigation of the filtration process of metal oxide nanoparticles: TiO₂, MgO, and Al₂O₃ by electrospun nanofibrous filter. The filter was produced from polyvinylidene fluoride (PVDF). The concentration of polymer dissolved in dimethylacetamide (DMAC) and acetone mixture was 15 wt.%. The flow rate of polymer solution was 1 mL/h. The nanoparticle aerosol was produced by the atomization of a suspension of these nanoparticles in a solvent (methanol) using an aerosol generator. The experimental results presented in this paper show that nanofilters made of PVDF with surface density of 13 g/m² have a high filtration efficiency for nano- and microparticles, larger than 90%. The gas flow rate through the channel was set to 960 and 670 l/min. The novelty of this paper was the investigation of air filtration from various types of nanoparticles produced by different nanotechnology processes by nanofibrous filters and studies of the morphology of nanoparticle deposited onto the nanofibers. Full article

The application of metal–organic frameworks (MOFs) has attracted increasing attention in organic synthesis. The modification of MOFs can efficiently tailor the structure and improve the property for meeting ongoing demand in various applications, such as the alteration of gas adsorption and separation, catalytic activity, stability, and sustainability or reusability. In this study, carboxyethylsilanetriol (CEST) disodium salt was used as a dual-functional ligand for modified Al-MIL-53 to fabricate CEST-functionalized Al-MIL-53 samples through a hydrothermal reaction of aluminum nitrate, terephthalic acid, and CEST disodium salt by varying the molar ratio of CEST to terephthalic acid and keeping a constant molar ratio of Al³⁺/-COOH of 1:1. The structure, composition, morphology, pore feature, and stability were characterized by XRD, different spectroscopies, electron microscopy, N₂ physisorption, and thermogravimetric analysis. With increasing CEST content, CEST-Al-MIL-53 still preserves an Al-MIL-53-like structure, but the microstructure changed compared with pure Al-MIL-53 due to the integration of CEST. Such a CEST-Al-MIL-53 was used as the support to load Pd particles and afford a catalyst Pd/CEST-Al-MIL-53 for Suzuki–Miyaura C-C cross-coupling reaction of aryl halides and phenylboronic acid under basic conditions. The resulting Pd/CEST-Al-MIL-53 showed a high catalytic activity compared with Pd/Al-MIL-53, due to the nanofibrous structure of silicon species-integrated CEST-Al-MIL-53. The nanofiber microstructure undergoes a remarkable transformation into intricate 3D cross-networks during catalytic reaction, which enables the leachable Pd particles to orientally redeposit and inlay into these networks as the monodisperse spheres and thereby effectively preventing Pd particles from aggregation and leaching, therefore demonstrating a high catalytic performance, long-term stability, and enhanced reusability. Obviously, the integration of CEST into MOFs can effectively prevent the leaching of active Pd species and ensure the re-deposition during catalysis. Moreover, catalytic performance strongly depended on catalyst dosage, temperature, time, solvent, and the type of the substituted group on benzene ring. This work further extends the catalytic application of hybrid metal–organic frameworks. Full article

In this paper, we explore a straightforward two-step method to produce high-purity, vertically aligned multi-walled carbon nanofibres (MWCNFs) via chemical vapor deposition (CVD). Two distinct solutions are utilized for this CVD method: a catalytic solution consisting of ferrocene and acetonitrile (ACN) and a carbon source solution with camphor and ACN. The vapors of the catalytic solution inserted in the reaction chamber through external boiling result in a floating catalyst CVD approach that produces vertically aligned CNFs in a consistent manner. CNFs are grown in a conventional CVD horizontal reactor at 850 °C under atmospheric pressure and characterized by Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Coating the MWCNTs with polymethyl methacrylate (PMMA) while still on the Si substrate retains the structure and results in a flexible, conductive thin film suitable for flexible electrodes. The film is 62 μm thick and stable in aqueous solutions, capable of withstanding further processing, such as electropolymerization with polyaniline, to be used for energy storage applications. Full article

In this work, non-precious electrocatalysts were synthesized using the electrospinning technique. Ni₁₂M₈/CNF (M = Cd, Co, and Cu) catalysts were successfully prepared in a fixed ratio to withstand the optimum transition metal co-catalyst in addition to the role of CNFs as support in ion-charge movement through the catalyst surface. The prepared catalysts were physically studied by XRD, SEM, and TEM. The electrochemical activity was verified using different fuel concentrations, different sweeping scan rates, and electrochemical impedance. Ni₁₂Cu₈/CNFs showed the highest electrochemical activity reaching 152 mA/cm² through different methanol concentrations. The outstanding performance is attributed to the large active surface area provided by carbon nanofibrous that eases the charge carrier transfer through the untrapped surface of the catalyst. The electrochemical tests suggest that Ni₁₂Cu₈/CNFs have the lowest ohmic impedance resistance ensuring the highest efficiency of the designed catalyst. The obtained results serve as an efficient catalyst for direct methanol electrooxidation reactions and suggest a possible application of a low-cost, easily accessible, and large surface area established via the preparing method. Full article

Developing high-performance and low-cost protein purification materials is of great importance to meet the demands for highly purified proteins in biotechnological industries. Herein, a facile strategy was developed to design and construct high-efficiency protein absorption and separation media by combining aerogels’ molding techniques and impregnation processes. Poly (ethylene-co-vinyl alcohol) (EVOH) nanofibrous aerogels (NFAs) were modified by grafting butane tetracarboxylic acid (BTCA) over them in situ. This modification was carried out using polyphosphoric acid as a catalyst. The resulting EVOH/BTCA NFAs exhibited favorable comprehensive properties. Benefiting from the highly interconnected porous structure, good underwater compressive properties, and abundant absorption ligands, the obtained EVOH/BTCA NFAs possessed a high static absorption capacity of 1082.13 mg/g to lysozyme and a short absorption equilibrium time of about 6 h. A high saturated dynamic absorption capacity for lysozyme (716.85 mg/g) was also realized solely by gravity. Furthermore, EVOH/BTCA NFAs displayed excellent reusability, good acid and alkaline resistance, and unique absorption selectivity performance. The successful synthesis of such aerogels can provide a potential candidate for next-generation protein absorbents for bio-separation and purification engineering. Full article

The phase composition and comparison of iron-based catalysts used for the synthesis of carbon nanotubes were investigated. This work reflects typical catalyst conditions and their evolution during the growth of carbon nanotubes. The preparation of carbon nanotubes was carried out by chemical vapour deposition at temperatures between 800 and 1100 °C. Ferrocene or zero-valent iron nanoparticles were used as “catalysts”, and toluene, ferrocene and the ferrocene–toluene solution played the role of carbon precursors, respectively. The phase composition of the prepared product was studied by Mössbauer spectroscopy and X-ray powder diffraction. Mössbauer analysis was particularly useful for samples with a low content of the nanoparticle form of the catalyst. The composition of the prepared samples differed depending on the synthesis temperature, catalyst and precursor. Phase analysis revealed the presence of α-Fe and Fe₃C in all samples. In addition, γ-Fe and iron oxides were identified under certain conditions. Scanning and transmission electron microscopy confirmed the carbon nanotube/nanofibre-like morphology and the presence of iron species. Full article

The conversion of hydrogen to power via combined external reforming of liquid alcohol and solid oxide fuel cell (SOFC) technology is an effective approach to address future energy challenges. In this study, an La_0.8Ba_0.1Mn_0.8Ni_0.1Cu_0.1O₃ (LBMNCu) perovskite nanofiber with high porosity was synthesized with a modified electrostatic spinning method, which acted as an efficient catalyst for steam reforming of liquid alcohols (methanol and ethanol). After reduction, fine metallic Ni-Cu was uniformly distributed throughout the perovskite nanofiber surface. The obtained composite displayed a methanol conversion above 99.9% at 450 °C and an ethanol conversion above 99% at 600 °C, which was highly superior to the common Ni-Cu/Al₂O₃ catalyst. The catalytic performance of our assembled catalysts also remained stable in methanol and ethanol atmospheres for 50 h and no coking was detected. Furthermore, when the reformed gas was fed into a Y_0.08Zr_0.92O₂ (YSZ)-based SOFC system, the open circuit voltage remained around 1.1 V at 700 °C for 50 h accordingly, without coking, and the voltage remained virtually unchanged at 0.7 V for 50 h at 700 °C and 400 mA cm⁻² during galvanostatic discharge mode, indicating that using LBMNCu nanofiber as a catalyst for hydrogen production and utilization is an efficient strategy. The interaction of the in situ exsolved metallic nanoparticles and nanofibrous perovskite could also be a promising approach for designing a highly active catalyst for H₂ generation. Full article

The goal of achieving the large-scale production of zero-emission vehicles by 2035 will create high expectations for electric vehicle (EV) development and availability. Currently, a major problem is the lack of suitable batteries and battery materials in large quantities. The rechargeable zinc–air battery (RZAB) is a promising energy-storage technology for EVs due to the environmental friendliness and low production cost. Herein, iron, cobalt, and nickel phthalocyanine tri-doped electrospun carbon nanofibre-based (FeCoNi-CNF) catalyst material is presented as an affordable and promising alternative to Pt-group metal (PGM)-based catalyst. The FeCoNi-CNF-coated glassy carbon electrode showed an oxygen reduction reaction/oxygen evolution reaction reversibility of 0.89 V in 0.1 M KOH solution. In RZAB, the maximum discharge power density (P_max) of 120 mW cm⁻² was obtained with FeCoNi-CNF, which is 86% of the P_max measured with the PGM-based catalyst. Furthermore, during the RZAB charge–discharge cycling, the FeCoNi-CNF air electrode was found to be superior to the commercial PGM electrocatalyst in terms of operational durability and at least two times higher total life-time. Full article

Catalysts are used for producing the vast majority of chemical products. Usually, catalytic membranes are inorganic. However, when dealing with reactions conducted at low temperatures, such as in the production of fine chemicals, polymeric catalytic membranes are preferred due to a more competitive cost and easier tunability compared to inorganic ones. In the present work, nanofibrous mats made of poly(ethylene oxide), PEO, and poly(ethylene glycol) diacrylate, PEGDA, blends with the Au/Pd catalyst are proposed as catalytic membranes for water phase and low-temperature reactions. While PEO is a water-soluble polymer, its blending with PEGDA can be exploited to make the overall PEO/PEGDA blend nanofibers water-resistant upon photo-crosslinking. Thus, after the optimization of the blend solution (PEO molecular weight, PEO/PEGDA ratio, photoinitiator amount), electrospinning process, and UV irradiation time, the resulting nanofibrous mat is able to maintain the nanostructure in water. The addition of the Au₆/Pd₁ catalyst (supported on TiO₂) in the PEO/PEGDA blend allows the production of a catalytic nanofibrous membrane. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), taken as a water phase model reaction, demonstrates the potential usage of PEO-based membranes in catalysis. Full article

Fiber electronics, such as those produced by the electrospinning technique, have an extensive range of applications including electrode surfaces for batteries and sensors, energy storage, electromagnetic interference shielding, antistatic coatings, catalysts, drug delivery, tissue engineering, and smart textiles. New composite materials and blends from conductive–semiconductive polymers (C-SPs) offer high surface area-to-volume ratios with electrical tunability, making them suitable for use in fields including electronics, biofiltration, tissue engineering, biosensors, and “green polymers”. These materials and structures show great potential for embedded-electronics tissue engineering, active drug delivery, and smart biosensing due to their electronic transport behavior and mechanical flexibility with effective biocompatibility. Doping, processing methods, and morphologies can significantly impact the properties and performance of C-SPs and their composites. This review provides an overview of the current literature on the processing of C-SPs as nanomaterials and nanofibrous structures, mainly emphasizing the electroactive properties that make these structures suitable for various applications. Full article

The present work investigates the effect of ultrasounds in the performance of combined advanced oxidation processes (AOPs) on the degradation of formaldehyde (HCHO)-polluted aqueous solutions for potential application in wastewater treatment. Different heterogeneous nanostructured catalysts based on TiO₂ and FeSO₄ for photocatalysis and the Fenton process were employed after electrospray deposition on electrospun nanofibrous membranes. Such systems were tested, without the use of any added hydrogen peroxide, by varying the combinations among the selected AOPs in a batch reactor configuration. The results show that, in the absence of a Fenton reaction, ultrasounds provided a significantly increased formaldehyde photocatalytic abatement, probably by increasing the concentration of active species through a different set of reactions while providing a favorable mass transfer regime by the cavitational effect. Due to the faster kinetics of the photo–Fenton process, thanks to its partial homogeneous nature, such a beneficial effect is more limited for the sono–photo–Fenton configuration. On the other hand, the employment of a sono–photocatalytic–Fenton process revealed a synergic effect that provided the best results, reducing the formaldehyde concentration to less than 99% after 240 min. Further analysis showed that, due to a mutual influence, only a tailored TiO₂/FeSO₄ ratio on the membranes was able to display the best performance. Full article

The hydrogenation products of aromatic molecules with reducible groups (such as C=C, NO₂, C=O, etc.) are relatively critical intermediate compounds in fine chemicals, but how to accurately reduce only specific groups is still challenging. In this work, a bimetallic Pt-Ni/Chitin catalyst was prepared for the first time by using renewable biomass resource chitin as support. As the carrier, the chitin was constructed into porous nanofibrous microspheres through the sol-gel strategy, which was favorable for the adhesion of nano-metals and the exchange of reactive substances due to its large surface area, porous structure, and rich functional groups. Then the Pt-Ni/Chitin catalyst was applied to selective hydrogenation with the model substrate of 4-nitrostyrene. As the highly dispersed Pt-Ni NPs with abundant exposed active sites and the synergistic effect of bimetals, the Pt-Ni/Chitin catalyst could efficiently and selectively hydrogenate only NO₂ or C=C with yields of ~99% and TOF of 660 h⁻¹, as well as good stability. This utilization of biomass resources to build catalyst materials would be important for the green and sustainable chemistry. Full article