Showing papers on "Vanadate published in 2022"

Potassium Ammonium Vanadate with Rich Oxygen Vacancies for Fast and Highly Stable Zn-Ion Storage.

Abstract: Vanadium-based materials have been extensively studied as promising cathode materials for zinc-ion batteries because of their multiple valences and adjustable ion-diffusion channels. However, the sluggish kinetics of Zn-ion intercalation and less stable layered structure remain bottlenecks that limit their further development. The present work introduces potassium ions to partially substitute ammonium ions in ammonium vanadate, leading to a subtle shrinkage of lattice distance and the increased oxygen vacancies. The resulting potassium ammonium vanadate exhibits a high discharge capacity (464 mAh g-1 at 0.1 A g-1) and excellent cycling stability (90% retention over 3000 cycles at 5 A g-1). The excellent electrochemical properties and battery performances are attributed to the rich oxygen vacancies. The introduction of K+ to partially replace NH4+ appears to alleviate the irreversible deammoniation to prevent structural collapse during ion insertion/extraction. Density functional theory calculations show that potassium ammonium vanadate has a modulated electron structure and a better zinc-ion diffusion path with a lower migration barrier.

Co-intercalation strategy of constructing partial cation substitution of ammonium vanadate {(NH4)2V6O16} for stable zinc ion storage.

Abstract: Recently, aqueous zinc-ion batteries have become a hot research topic in the field of grid-scale application, which can be attributed to their low-cost, aqueous electrolyte and dominant theoretical reversible capacity. Nevertheless, the lack of suitable cathode materials greatly hinders the development of aqueous zinc-ion batteries. In this work, we adopt a simple one-step synthesis strategy to prepare (NH4)2V6O16 with an intercalation of Na+ and H2O, which exhibits a novel crystal structure in which the ammonium ion, crystal water, and sodium ion co-locate in the V3O8 layers. The co-intercalation not only effectively enhances the binding energy between V-O layers to suppress vanadium dissolution but also successfully improves the structural stability to alleviate the structural collapse during the cyclic process. As result, (NH4)2V6O16 with the intercalation of crystal water and Na+ presents a remarkable reversible discharge capacity of 423.9 mA h g-1 after 90 cycles at 0.1 A g-1 with an excellent energy density of 350.3 W h kg-1 and demonstrates an outstanding specific capacity of 182.5 mA h g-1 at the high current density of 5 A g-1 upon 1400 cycles during the ultra-wide voltage window of 0.1-2.0 V.

Engineering titanium-organic framework decorated silver molybdate and silver vanadate as antimicrobial, anticancer agents, and photo-induced hydroxylation reactions

Abstract: Hydroxylation is a chemical process that presents a hydroxyl group (–OH) into a natural compound. It is greatly vital in detoxification of unsafe compounds to clean the environment and giving new functionality to organic compounds. Therefore, investigation multi-properties of metal organic frameworks (MOFs) are most critical field. Here, titanium based MOFs (MIL-125-NH2) was enhanced with silver molybdate (Ag2MoO4) and silver vanadate (AgVO3) nanocrystals. The component of joining Ag2MoO4 and AgVO3 into MIL-125-NH2 network has been examined. The novel arranged composites were tried to change aromatic-Cl into aromatic-OH, the chemical response continues through the addition–elimination reactions. The expansion of our work focuses on examining the effect of MOFs on both of antimicrobial and anticancer agents. Surprising data comes over when using Ag2MoO4@MIL-125-NH2 nanocomposite as anti-bacterial material; the inhibition zone was minimized (seven times less) when treated with a parent Ti-MOFs (MIL-125-NH2) match with its Ti-MOFs composite (Ag2MoO4@MIL-125-NH2). As well as, the potential of anticancer activity for Ti-MOFs composite (Ag2MoO4@MIL-125-NH2) display 1.58 times more than a parent Ti-MOFs.

Engineering titanium-organic framework decorated silver molybdate and silver vanadate as antimicrobial, anticancer agents, and photo-induced hydroxylation reactions

Abstract: Hydroxylation is a chemical process that presents a hydroxyl group (–OH) into a natural compound. It is greatly vital in detoxification of unsafe compounds to clean the environment and giving new functionality to organic compounds. Therefore, investigation multi-properties of metal organic frameworks (MOFs) are most critical field. Here, titanium based MOFs (MIL-125-NH2) was enhanced with silver molybdate (Ag2MoO4) and silver vanadate (AgVO3) nanocrystals. The component of joining Ag2MoO4 and AgVO3 into MIL-125-NH2 network has been examined. The novel arranged composites were tried to change aromatic-Cl into aromatic-OH, the chemical response continues through the addition–elimination reactions. The expansion of our work focuses on examining the effect of MOFs on both of antimicrobial and anticancer agents. Surprising data comes over when using Ag2MoO4@MIL-125-NH2 nanocomposite as anti-bacterial material; the inhibition zone was minimized (seven times less) when treated with a parent Ti-MOFs (MIL-125-NH2) match with its Ti-MOFs composite (Ag2MoO4@MIL-125-NH2). As well as, the potential of anticancer activity for Ti-MOFs composite (Ag2MoO4@MIL-125-NH2) display 1.58 times more than a parent Ti-MOFs.

Oxygen evolution reaction at the Mo/W-doped bismuth vanadate surface: Assessing the dopant role by DFT calculations

Abstract: The first-principles investigation of M-doped BiVO4-based materials (M = Mo, W) provides a comprehensive understanding of the dopant role in enhancing the photocatalytic properties for Oxygen Evolution Reaction (OER), which is the key-process for water splitting. We found that the beneficial effect of Mo/W doping on bismuth vanadate stems from structural surface re-organizations with the formation of a peculiar site (Biopp), which stabilizes both hydration and catalytic capabilities. Water adsorption is more favourable on Biopp site rather than on top of the dopant Mo/W atoms. Also, the catalytic performances for OER are significantly improved at Biopp site thanks to a stabilization of the crucial intermediate along the OER mechanism. Therefore, the Mo/W dopants exert a non-innocent indirect effect on the catalysis by activating the under-coordinated Biopp site via a long-range pull-back mechanism. These findings pave the route to new design strategies based on doping and defect engineering to push further the development of new photocatalysts for water splitting.

UV-light-induced photocatalytic response of Pechini sol–gel synthesized erbium vanadate nanostructures toward degradation of colored pollutants

Abstract: This study investigates synthesis of erbium vanadate nanostructures via carboxylic-assisted pechini method to optimization the morphology, size and physicochemical properties. The optimized ErVO 4 nanoparticles with range size of 12–98 nm were subjected to photocatalytic ability for dye decolorization of Methyl orange (MO), Erythrosine (ER), and Methylene blue (MB) using ultraviolet irradiation. The correlation between the operational parameters (pollutant concentration and catalyst loading) and optoelectronic properties in addition to the catalytic performance of the ErVO 4 structure is reported. The ideal condition for activity of ErVO 4 nano-photocatalyst achieved in the 10 ppm aqueous solution of MB with catalyst loading of 0.05 g which presents 77.85% efficiency for decolorization of colored pollutant model. The recycle photocatalytic efficiency after 4 cycles is about 69.25%. Additionally, the photocatalytic mechanism direction studied in the presence of some scavengers which confirms the role of hydroxyl radical in the removal of MB. The magnetic properties of ErVO 4 studied through VSM which shows the paramagnetic behavior with saturation magnetization is 1.3341 emu g − 1 . • Synthesis of ErVO 4 using Pechini method in the presence of carboxylic acids. • Effect of carboxylic acids and diol agents inquired on the structure and purity. • Photocatalytic activity studied through modifying operational parameters. • Scavenger studies confirmed the photocatalytic mechanism and reactive species.

Aluminium vanadate with unsaturated coordinated V centers and oxygen vacancies: surface migration and partial phase transformation mechanism in high performance zinc-ion batteries

Abstract: Aluminium vanadate with unsaturated coordinated V centers and oxygen vacancies shows excellent Zn 2+ storage due to the low Zn 2+ migration barrier along the (001) surface, the co-(de)intercalation mechanism of H + /Zn 2+ and the partial transformation.

Synthesis and optical spectroscopy of Na3Y(VO4)2:Eu3+ phosphors for thermometry and display applications

Abstract: A new Na3Y(VO4)2:Eu3+ (NYVO:Eu3+) phosphor was prepared using the sol–gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to evaluate phase purity and particle size, respectively. The optical properties were investigated by UV-visible absorption, PL, and PLE spectroscopies. The absorption measurements show the formation of the vanadate host by the presence of its characteristic band in the visible region related to VO43− groups. The experimental results show that the NYVO:Eu3+ phosphors exhibit high-brightness and thermally stable emission. Under near-ultraviolet (UV) excitation, both the broadband emission from VO43− groups and the sharp peak emissions from Eu3+ ions are observed. The highest luminescence intensity was achieved for an optimal europium concentration of 15 mol%. The study of the chromaticity parameters of these compounds gives a thermally stable hot emission in the red domain, with a color purity of about 85%, which qualifies the NYVO:Eu3+ compound as a potential phosphor for light-emitting diode (LED) applications. Thermal sensing using NYVO:Eu3+ phosphors are based on monitoring the luminescence intensity ratio between the NYVO host emission and Eu3+ luminescence lines. Notably, the optical thermometry of NYVO:Eu3+ was characterized based on the fluorescence intensity ratio of VO43− and Eu3+ emissions in the 298–440 K range, with maximum absolute and relative sensitivities of 3.4% K−1 and 0.0032 K−1 respectively and a temperature uncertainty of 0.01. NYVO:Eu3+ can then be considered as a potential red phosphor for application in ultraviolet-pumped white light-emitting diodes and as a potential optical thermometer. It provides new possibilities for the design of multifunctional materials for red light-emitting diodes and for non-contact thermometry.

Aqueous zinc ion batteries based on sodium vanadate electrode materials with long lifespan and high energy density

Abstract: We have prepared Na 7 V 7.6 O 20 ·4H 2 O (NVO) nanobelts by a facile hydrothermal route. The assembled NVO/Zn batteries deliver a capacity of 309.4 mA h g −1 at 0.3 A g −1 and maintain excellent cycling stability after 10 000 cycles at 10 A g −1 .

Piezo-Photocatalytic and Photocatalytic Bismuth Vanadate Nanorods with Antibacterial Property

Abstract: Piezo-photocatalysis, which combines the piezoelectric and photoresponsive behavior of materials, is considered a promising strategy for water treatment. As an established piezomaterial, herein, we report the photocatalytic, piezocatalytic, and piezo-photocatalytic responses of bismuth vanadate (BiVO4) nanorods under ultrasonic frequency (35 kHz) and selected visible light excitation. We used a facile hydrothermal method to produce BiVO4 nanorods. The as-synthesized (B180) and calcined (C300, C500, and C700) BiVO4 crystallizes in the monoclinic scheelite phase. The essential traits shown by BiVO4 nanorods are extended visible-near-infrared absorption and high Bi5+/Bi3+ and V4+/V5+ ratios, inferring a high content of oxygen defects. The photo and piezo responsive behavior are tested with Methylene Blue (MB) as a standard organic pollutant. The piezocatalytic and piezo-photocatalytic processes are activated in BiVO4 through feeding ultrasonic mechanical vibrations, which elicit polarization and separation of charges in BiVO4 nanorods. The photocatalytic and piezo-photocatalytic methods led to 97.63 and 97.13% MB degradation in 40 min. It is found that piezo-photocatalysis is dominant for a short period, but eventually, it slows with time. It can be ascribed to sonication’s fracturing effect, which further exacerbates the catalytic process due to the damage to the catalytic sites. Additionally, the photocatalytic inactivation of Gram-positive Staphylococcus aureus) and Gram-negative Escherichia coli K12) bacteria was investigated under visible light irradiation using C300 and C500 samples. Within 120 min, C500 exhibited 97.24 and 90.44% mortality rates compared to C300, exhibiting 72.83 and 71.16% against S. aureus and E. coli K12, respectively.

From vanadium slag to multi-cations intercalated V2O5·nH2O: low-cost direct synthesis and high-performance aqueous battery application

Abstract: Although hydrated vanadate compounds have received extensive attention in aqueous batteries for their high specific capacity, they are still impeded by the poor cycling resulting from host structure degradation and...

Fabrication of Praseodymium Vanadate Nanoparticles on Disposable Strip for Rapid and Real-Time Amperometric Sensing of Arsenic Drug Roxarsone.

Abstract: Nanomaterials have versatile properties owing to their high surface-to-volume ratio and can thus be used in a variety of applications. This work focused on applying a facile hydrothermal strategy to prepare praseodymium vanadate nanoparticles due to the importance of nanoparticles in today's society and the fact that their synthesis might be a challenging endeavor. The structural and morphological characterizations were carried out to confirm the influence of the optimizations on the reaction's outcomes, which revealed praseodymium vanadate (PrVO4) with a tetragonal crystal system. In this regard, the proposed development of electrochemical sensors based on the PrVO4 nanocatalyst for the real-time detection of arsenic drug roxarsone (RXS) is a primary concern. The detection was measured by amperometric (i-t) signals where PrVO4/SPCE, as a new electrochemical sensing medium for RXS detection, increased the sensitivity of the sensor to about ∼2.5 folds compared to the previously reported ones. In the concentration range of 0.001-551.78 μM, the suggested PrVO4/SPCE sensor has a high sensitivity for RXS, with a detection limit of 0.4 nM. Furthermore, the impact of several selected potential interferences, operational stability (2000 s), and reproducibility measurements have no discernible effect on RXS sensing, making it the ideal sensing device feasible for technical analysis. The real-time analysis reveals the excellent efficiency and reliability of the prosed sensor toward RXS detection with favorable recovery ranges between ±97.00-99.66% for chicken, egg, water, and urine samples.

New Structural Design Strategy: Optical Center VO4-Activated Broadband Yellow Phosphate Phosphors for High-Color-Rendering WLEDs

Abstract: Optical center VO4-activated non-rare-earth phosphors featuring impressive broadband emission are emerging as alternatives to rare-earth phosphors for lightings. However, most VO4-activated phosphors merely exist in vanadates and suffer from serious luminescence thermal quenching, which hinder the development of advanced VO4-activated phosphors. Herein, we put forward a new strategy of constructing optical center VO4 in non-vanadate compounds with thermal stability to enrich the number and variety of VO4-activated phosphors and improve their thermal stability. In this study, detailed structural analysis and theoretical calculation show that we have successfully constructed VO4 groups with a highly electron-localized property by substituting P5+ in the K2BaCa(PO4)2 (KBCP) host with V5+, confirming the formation of VO4 centers. In K2BaCa(PO4)2–x(VO4)x (KBCP2–xVx) compounds, the appearance of VO4 groups significantly enhances the absorption efficiency of near-ultraviolet light, yielding a broadband yellow emission centered at 568 nm, with a full width at half-maximum of 213 nm. At 150 °C, the KBCP1.8V0.2 sample shows superior thermal stability with an emission loss of only 10%, surpassing the performances of VO4-activated vanadate phosphors ever reported. Using the KBCP1.8V0.2 phosphor, the resulting white-light-emitting diodes (WLEDs) show a high color rendering index of 87.3–93.4 and a wide range of correlated color temperatures of 4357–6510 K. Our results may stimulate more research on anionic-group-activated phosphors and accelerate the development of advanced VO4-activated phosphors.