Niobium Pentoxide Research Articles

Niobium Pentoxide as an Acid Catalyst: An Overview

The global chemical industry is under increasing pressure to adopt more sustainable practices, as most chemical products exceed environmental safety limits. Given that chemical production largely relies on catalytic processes, the development of solid acid catalysts has become crucial for more sustainable production. Among these catalysts, niobium pentoxide stands out due to its strong acid sites, which remain active in the presence of water, and its stability under hydrothermal conditions. Recent studies have demonstrated that these solids maintain their catalytic activity even in the presence of strong bases, making them unique catalysts. This review explores the potential of niobium pentoxide as an acid catalyst, addressing advances in synthesis techniques, surface modifications, and combinations with other materials to enhance its catalytic performance in sustainable applications, such as biomass conversion and biofuel production, opening new pathways for the production of greener chemicals. Finally, the future perspectives of niobium pentoxide - based catalysts in green chemistry are discussed.

Aliovalent Doping of Niobium and Tantalum Pentoxide as Potential Alternative Support Material for Fuel Cell Catalysts

AbstractAs the usually used Carbon Blacks (CB) as support materials in fuel cell catalysts are thermodynamically unstable, alternative supports with high chemical stability and electrical conductivity are to be found. After the investigation of Nb and Ta‐doped SnO2 in an earlier publication, which revealed interesting conductivity properties, we expanded our portfolio of mutual doping of elements of stable oxides into the oxides of the others by reporting here on the Sn, Hf and W‐doping as guests into the base oxides Nb2O5 and Ta2O5. The changes in unit cell parameters as indicators for the doping success were investigated in the doping range of x=0–10 mol % guest fraction. From a complete solubility of the guest ions in case of Hf and W‐doping in the base oxides to a limited solubility in case of Sn‐doping, a whole spectrum of different results was obtained. Additional insight came from UV/vis spectroscopic investigations in diffuse reflectance as well as electrical conductivity measurements.

Development of new cathode materials for all-iron redox flow batteries using hard carbon-based composites containing niobium pentoxide

We report in this study new cathodes for all-Fe RFBs synthesized using carbon flakes dispersed in plasticizing and hardening agents to obtain hard and dense carbon (HC) materials in the absence and presence (HC-Nb) of niobium pentoxide (Nb2O5). These cathode materials exhibited excellent resistance to wear in acidic solutions and larger potential intervals for water stability (e.g., 1200–1300 mV) compared to conventional graphite (e.g., 800 mV). These characteristics decreased the parasitic occurrence of hydrogen evolution reaction (HER) using a laboratory-made battery cell during the charging process. The latter was based on the Fe0/Fe2+ and Fe2+/Fe3+ redox couples present in the anode and cathode compartments, respectively. The different ex-situ and in-situ characterization studies evidenced that the presence of Nb2O5 in HCs substantially changed their physicochemical properties. The highest heterogenous kinetic rate constant (k0) representing the electrocatalytic activity for electron transfer was verified for the cathode containing 10 wt.% Nb2O5. An electromotive force (EMF) of 1.053 V was verified for the fully charged all-Fe RFB. Galvanostatic charge–discharge (GCD) studies revealed excellent coulombic efficiency (> 88 %) after 300 cycles. A pH control by acid addition as a function of the battery operation is necessary to avoid iron hydroxide formation on the anode’s surface.

Anion-Anchored Polymer-in-Salt Solid Electrolyte for High-Performance Zinc Batteries.

Solid polymer electrolytes hold promise for addressing key challenges in rechargeable zinc batteries (ZBs) utilizing aqueous electrolytes. However, achieving simultaneous high ionic conductivity, excellent mechanical strength, and a high cation transference number while effectively suppressing Zn dendrites remains challenging. Herein, we design a novel polymer-in-salt solid electrolyte (PISSE) composed of polyacrylonitrile (PAN), zinc chloride (ZnCl2), and niobium pentoxide with oxygen vacancies (Nb2O5-x) with high ionic conductivity. PAN polymer matrix provides the electrolyte good mechanical properties and solubility of Zn salt. The high concentration of ZnCl2 effectively decouples the Zn2+ from polymer chain segments and provides more ionic conduction amorphous region. Moreover, incorporating Nb2O5-x filler accelerates Zn2+ desolvation by anchoring (ZnxCly)2x-y clusters and enhances the system's mechanical properties, achieving a superior Zn2+ transference number (~0.93) and interfacial stability. Consequently, the optimized PISSE demonstrates exceptional stability during prolonged cycling periods, wide temperature range operation (-40 ℃ to 60 ℃), remarkable flexibility, and compatibility with diverse electrode materials. This study provides valuable insights into the design of solid-state electrolytes based on ZBs and elucidates their multifunctional prospects.

Wide spectral range optical characterization of niobium pentoxide ([formula omitted]) films by universal dispersion model

In this work, the optical properties of niobium pentoxide (Nb2O5) films were extensively studied across a wide spectral range using heterogeneous data-processing methods, combining ellipsometric and spectrophotometric measurements for five samples with thicknesses between 20 and 250 nm. This study primarily determined the optical constants of Nb2O5 from the far infrared to the vacuum ultraviolet, presenting these constants as dispersion parameters using the universal dispersion model to describe valence electron excitations in ultraviolet region as well as phonon vibrations in infrared region. These comprehensive and reliable data across such a broad spectral range are unprecedented. Secondly, presented optical characterization proofs that Nb2O5 films can be grown without defects such as surface roughness, porosity, or inhomogeneity. This fact, together with its high refractive index, makes Nb2O5 a promising material for optical applications.

Investigation of Oxide Layer Development of X6CrNiNb18-10 Stainless Steel Exposed to High-Temperature Water.

The oxide layer development of X6CrNiNb18-10 (AISI 347) during exposure to high-temperature water has been investigated. Stainless steels are known to form a dual oxide layer in corrosive environments. The secondary Fe-rich oxide layer has no significant protective effect. In contrast, the primary Cr-rich oxide layer is known to reach a stabilized state, protecting the base metal from further oxidation. This study's purpose was to determine the development of oxide layer dimensions over exposure time using SEM, TEM and EDX line scans. While a parabolic development of Cr in the protective primary layer and Fe in the secondary layer was observed, the dimensions of the Ni layer remained constant. Ni required the presence of a pronounced Fe-rich secondary layer before being able to reside on the outer secondary layer. With increasing immersion time, the Ni element fraction surpassed the Cr element fraction in the secondary layer. Oxide growth on the secondary layer could be observed. After 480 h, nearly the entire surface was covered by the outer oxide layer. In the metal matrix, no depletion of Cr or Ni could be observed over time; however, an increased presence of Cr and Ni in the primary layer was found at the expense of Fe content. The Nb-stabilized stainless steel was subject to the formation of Niobium pentoxide (Nb2O5), with the quantity and magnitude of element fraction increasing over exposure time.

Effects of indium selenide substrates on the performance of niobium pentoxide optoelectronic devices

Effects of indium selenide substrates on the performance of niobium pentoxide optoelectronic devices

Phase engineering of H/T-Nb2O5 homojunction for enhanced lithium-ion storage

Phase engineering has gained significant attention in energy-storage applications due to its ability to tailor the physicochemical properties and functionalities of electrode materials. In this study, we demonstrate the in-situ partial phase conversion of niobium pentoxide (Nb2O5), resulting in the formation of a monoclinic/orthorhombic (H/T-Nb2O5) heterophase homojunction. This study further confirms that the unique heterophase interface plays a crucial role in regulating the local electronic environment, resulting in charge redistribution, the formation of an internal electric field, and enhanced electron transfer. Moreover, the presence of abundant phase interfaces offers additional reactive sites for Li+ ion adsorption, thereby enhancing reaction dynamics. The synergistic effects within the H/T-Nb2O5 homojunction are reflected in its high Li+ storage capacity (413 mAh g−1 at 100 mA g−1), superior rate capability, and cycling stability. Thus, this study demonstrates that the construction of heterophase homojunctions offers a promising strategy for developing high-performance anode materials for efficient Li-ion storage.

Oxygen vacancies in niobium pentoxide as a source of two-level system losses in superconducting niobium

Oxygen vacancies in niobium pentoxide as a source of two-level system losses in superconducting niobium

Photoacoustic Spectroscopy of Titanium Dioxide, Niobium Pentoxide, Titanium:Niobium, and Ruthenium-Modified Oxides Synthesized Using Sol-Gel Methodology.

The aim of this work was the development and morphological/chemical, spectroscopic, and structural characterization of titanium dioxide, niobium pentoxide, and titanium:niobium (Ti:Nb) oxides, as well as materials modified with ruthenium (Ru) with the purpose of providing improvement in photoactivation capacity with visible sunlight radiation. The new materials synthesized using the sol-gel methodology were characterized using the following techniques: scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), photoacoustic spectroscopy (PAS), and X-ray diffraction (XRD). The SEM-EDS analyses showed the high purity of the bases, and the modified samples showed the adsorption of ruthenium on the surface with the crystals' formation and visible agglomerates for higher calcination temperature. The nondestructive characterization of PAS in the ultraviolet visible region suggested that increasing calcination temperature promoted changes in chemical structures and an apparent decrease in gap energy. The separation of superimposed absorption bands referring to charge transfers from the ligand to the metal and the nanodomains of the transition metals suggested the possible absorption centers present at the absorption threshold of the analyzed oxides. Through the XRD analysis, the formation of stable phases such as T-Nb16.8O42, o-Nb12O29, and rutile was observed at a lower temperature level, suggesting pore induction and an increase in surface area for the oxides studied, at a calcination temperature below that expected by the related literature. In addition, the synthesis with a higher temperature level altered the previously existing morphologies of the Ti:Nb, base and modified with Ru, forming the new mixed crystallographic phases Ti2Nb10O29 and TiNb2O7, respectively. As several semiconductor oxide applications aim to reduce costs with photoexcitation under visible light, the modified Ti:Ru oxide calcined at a temperature of 800 °C and synthesized according to the sol-gel methodology used in this work is suggested as the optimum preparation point. This study presented the formation of a stable crystallographic phase (rutile), a significant decrease in gap energy (2.01 eV), and a visible absorption threshold (620 nm).

High Broadband Optical Absorption and Bandstop Filter Characteristics of Pb/Nb2O5 Interfaces

AbstractIn this study, semitransparent lead films serve as substrates for depositing niobium pentoxide thin films, forming versatile electro‐optical devices. Using vacuum evaporation and ion sputtering techniques at ≈10−5 mbar, stacked layers of crystalline Pb and amorphous Nb2O5 are created. This process reduces free carrier absorption in Nb2O5 and forms Urbach tail states with a width of 0.91 eV. Pb/Nb2O5 thin films exhibit remarkable broadband absorption, exceeding 440% in the visible and 98% in the infrared. Moreover, Pb substrates induce a redshift in Nb2O5’s energy bandgap. Electrical analysis using impedance spectroscopy on Pb/Nb2O5/Ag structures reveals their series/parallel resonance and bandstop filter properties. Notably, the bandstop filters exhibit reflection coefficient minima at a notch frequency of 1.66 GHz, with a bandwidth of 280 MHz, return loss of 26 dB, and voltage standing wave ratio of 1.13. These findings underscore the device's potential for wide‐ranging electro‐optical applications across the electromagnetic spectrum.

MECHANICAL STRENGTH ANALYSIS OF RESINS PRINTED WITH THE ADDITION OF NB2O5 NANOPARTICLES

Objective: To evaluate the strength of composite resins used for the fabrication of complete dentures after the addition of niobium pentoxide (Nb2O5). Methods: Different concentrations of Nb2O5 were added to the polymer matrix: 0% (control), 0.5%, 1.0%, 1.5%, and 2.0% per 100 mg of resin. In this context, nanoparticles were incorporated under ideal conditions, and the test specimens were designed using Dentsply Sirona’s inLab MC XL software. After the addition of nanoparticles, samples were printed with dimensions of 25 mm in width, 2 mm in height, and 2 mm in thickness. The test specimens were fabricated through digital printing. Finally, the samples were subjected to mechanical testing for flexural strength and impact resistance. Results: The 0.5% and 1.0% groups showed higher flexural strength values (54.56 and 56.8 MPa), with statistical significance (p<0.05) compared to the 1.5% and 2.0% groups (45.26 and 40.65 MPa). Regarding the modulus of elasticity, the 1.0% group presented the highest value (1.15 GPa), while the 0.5% group obtained 0.98 GPa, showing significant statistical differences (p<0.05) between the groups. In terms of impact resistance, the 0.5% and 2.0% groups exhibited the highest resistance, differing significantly from the 1.0% and 1.5% groups (p<0.05). Conclusion: Niobium pentoxide improved the properties of PMMA in this study, proving to be a viable alternative for the development of denture bases.

Unveiling niobium pentoxide and cerium oxide-dispersed ferritic stainless steel for solid oxide fuel cells interconnects

Herein, the effect of niobium pentoxide (Nb2O5) and nano-sized cerium oxide (CeO2) on oxidation behavior and area specific resistance (ASR) of the ferritic stainless steel has been investigated for the development of robust metallic interconnects. An oxide-dispersed ferritic stainless steel alloy is fabricated using the powder metallurgy (PM) process. The morphologies of the alloy before and after oxidation are observed through Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscopy (STEM) and Secondary Ion Mass Spectrometry (SIMS) analyses. Addition of Nb2O5 in the alloy formed a C14 Laves phase of (Fe, Cr)2(Nb, Si). The Laves phase and CeO2 controlled the oxidation behavior of the ferritic stainless steels, consequently reducing the oxide scale thickness and improving the ASR. An alloy with 1 wt% Nb2O5 and 3 wt% CeO2 showed an ASR value of 27.1 mΩ cm2 at 800 °C for 1000 h, which is similar to the ASR value of the commercial Fe–Cr alloy. The results of this study indicate that Nb2O5 and CeO2-dispersed ferritic stainless steel using the PM process can be more advantageous than the conventional process for manufacturing metallic interconnects with complex shapes and reducing production costs.

Unveiling the photocatalytic application of niobia based n-n heterojunction for degradation of tetracycline: A sustainable approach for water treatment

This study investigates the efficacy of a novel Nb2O5–MoO3 n-n heterojunction as a photocatalyst for the degradation of tetracycline in aqueous solution. The synthesized heterojunction shows remarkable photocatalytic activity attributed to the synergistic effect of niobium pentoxide (Nb2O5) and molybdenum trioxide (MoO3). Various characterization techniques, including X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy etc., were employed to elucidate the structural and morphological features of the heterojunction. The band gap energy and surface area were observed to be 2.55 eV and 32.897 m2/g respectively. The photocatalytic degradation of tetracycline was systematically studied under various experimental conditions, including catalytic dosage, initial tetracycline concentration and wavelength of irradiation light. These results reveal the greater efficiency of Nb2O5–MoO3 heterojunction compared to that of pristine Nb2O5 with a complete degradation achieved in 60 min under visible region with a degradation rate of 4.9 × 102 min−1. Furthermore, the catalyst demonstrates excellent stability over multiple cycles of use.

Sputtered niobium pentoxide layers for optical applications

The use of pulsed DC magnetron sputtered niobium pentoxide as a high index material in optical devices as Anti-Reflecting Coating (ARC) and optical filters has been investigated. When deposited on a silicon substrate with native oxide, the few nanometers of niobium pentoxide were optically distinct from the rest of the niobium pentoxide layer, effect not observed on thermally oxidized silicon substrates. The dispersion curve of this interfacial layer was determined and used to simulate the reflectometry curves. Next, an ARC consisting of a bilayer of niobium pentoxide and silica was fabricated and its optical response was simulated with this interfacial layer. Finally, a Bragg mirror consisting of seventeen layers of niobium pentoxide and silicon dioxide was realized, underlining that this interfacial layer does not affect the optical response when several layers were at stake.

Structural modulation of Nb2O5 for enhanced Lithium-ion battery Performance: Insights from density functional theory and electrochemical characterization

Lithium-ion batteries (LIBs), extensively utilized today, encounter challenges with anode materials, such as capacity degradation and shortened cycle life during prolonged cyclic charging and discharging. These issues significantly hinder further advancements and applications of LIBs. Among various innovative anode materials, niobium pentoxide (Nb2O5) has garnered considerable interest due to its high specific capacity and exceptional cycling stability. However, different crystal types of Nb2O5 have different structures and properties, so they need to be studied in depth to find better anode materials for LIBs. In this paper, pseudo-hexagonal (TT-Nb2O5), orthorhombic (T-Nb2O5), and monoclinic (H-Nb2O5) crystalline forms of Nb2O5 have been prepared by simple ball milling and calcination methods. We have calculated the structural model of the material based on the density flooding theory (DFT), and the results have demonstrated that the T-Nb2O5 has a large structural advantage, which is characterized by a very low diffusion energy barrier, a low internal resistance, and a higher conductivity. The electrochemical properties of the material were also analyzed, and T-Nb2O5 has excellent cycling stability and rate performance. After 200 cycles (at 0.1A/g), the specific capacity of T-Nb2O5 was maintained at 440.8mAh/g. 3000 cycles at high current (at 5A/g) maintained a specific capacity of 95mAh/g. T-Nb2O5 has great potential, which has already been proved. With the continuous pursuit and development of energy storage technology, we believe that the research of different crystalline types of Nb2O5 will provide us with more efficient and reliable energy storage solutions.

Synthesis and characterization of Nb5+ and Sm3+-doped 13–93 bioactive glass particles with improved photon transmission properties for advanced biomedical and dental applications

Bioactive glasses are renowned for their applications in dentistry, serving as restorative materials, dental adhesives, intracanal medicaments, and agents for enamel remineralization. Niobium pentoxide (Nb2O5) is employed in dental adhesive resins and orthodontic adhesives, offering radio-pacifying properties essential for dental materials. Samarium oxide (Sm2O3) emerges as a potential additive in aesthetic restorative dental ceramics and resins, enhancing the natural fluorescence of teeth. In this study Nb2O5 and Sm2O3-doped (1, 3, and 5 wt%) 13–93 bioactive glass particles were synthesized via the sol-gel method, tailored for dental implementations. We conducted a comprehensive analysis of the physical, structural, and optical properties of the resultant glass powders. Additionally, their in vitro bioactivity and ionizing radiation shielding characteristics were rigorously evaluated. The results indicate that Sm3+ ions preserve the amorphous nature of the silicate glasses, while Nb5+ incorporation leads to the crystallization of the T-Nb2O5 phase. Bioactivity assays across three physiological fluids—simulated body fluid, α-minimum essential medium, and phosphate-buffered saline, demonstrated the ability of doped glasses to facilitate hydroxyapatite layer formation, with the most pronounced bioactivity observed in phosphate-buffered saline immersed samples. Furthermore, radiation shielding simulations reveal that the addition of Nb2O5 and Sm2O3 enhances the ionizing radiation attenuation capabilities of the glasses, a property that holds significant promise for protecting against radiation in dental radiology. It can be concluded that the dual functionality of Nb5+ and Sm3+-doped bioactive glasses, which may revolutionize restorative dental practices and offer improved protection in radiological applications.

Well-dispersed Pt/Nb2O5 on zeolitic imidazolate framework derived nitrogen-doped carbon for efficient oxygen reduction reaction

In this work, an advanced hybrid material was constructed by incorporating niobium pentoxide (Nb2O5) nanocrystals with nitrogen-doped carbon (NC) derived from ZIF-8 dodecahedrons, serving as a support, referred to as Nb2O5/NC. Pt nanocrystals were dispersed onto Nb2O5/NC using a simple impregnation reduction method. The obtained Pt/Nb2O5/NC electrocatalyst showed high oxygen reduction reaction (ORR) activity due to three-phase mutual contacting structure with well-dispersed Pt and Nb2O5 NPs. In addition, the conductive NC benefits electron transfer, while the induced Nb2O5 can regulate the electronic structure of Pt element and anchor Pt nanocrystals, thereby enhancing the ORR activity and stability. The half-wave potential (E 1/2) for Pt/Nb2O5/NC is 0.886 V, which is higher than that of Pt/NC (E 1/2 = 0.826 V). The stability examinations demonstrated that Pt/Nb2O5/NC exhibited higher electrocatalytic durability than Pt/NC. Our work provides a new direction for synthesis and structural design of precious metal/oxides hybrid electrocatalysts.

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Synthesis of Niobium Pentoxide and Its Reduced Graphene Oxide Nanocomposite for Enhanced Supercapacitor Applications

Enhancing Thickness Uniformity of Nb2O5/SiO2 Multilayers Using Shadow Masks for Flexible Color-Filtering Applications.

Using a stainless shadow mask combined with a magnetron-ion-assisted deposition (IAD) sputtering system, we investigate the surface morphologies and optical properties of microfilms. Optimal color-filter (CF) coating microfilms with niobium pent-oxide (Nb2O5)/silicon dioxide (SiO2) multilayers on a hard polycarbonate (HPC) substrate, grown at 85 °C and 50 SCCM oxygen flow, can obtain a fairly uniform thickness (with an average roughness of 0.083 and 0.106 nm respectively for Nb2O5 and SiO2 films) through all positions. On a flexible HPC substrate with the Nb2O5/SiO2 microfilms, meanwhile, the peak transmittances measured in the visible range are 95.70% and 91.47%, respectively, for coatings with and without a shadow mask for this new-tech system. For the optimal CF application with a shadow mask, transmittance on each 100 nm band-pass wavelength is enhanced by 4.04% absolute (blue), 2.96% absolute (green), and 2.12% absolute (red). Moreover, the developed new-tech system not only enhances the quality of the films by achieving smoother and uniform surfaces but also reduces deposition time, thereby improving overall process efficiency. For the with-shadow-mask condition, there is little shift at 50% transmittance (T50%), and high transmittance (~97%) is maintained after high-temperature (200 °C) baking for 12 h. These results are well above the commercial CF standard (larger than 90%) and demonstrate reliability and good durability for flexible optical applications.