Doped V2O5 Research Articles

Effect of Mn dopant on physiochemical properties of V2O5 and their photocatalytic application toward mineralization of malachite green (MG) dye

The doping method is considered a proficient technique for enhancing the photocatalytic performance of nanostructures. Herein, doping of Mn into the V2O5 (VO) nanostructure increased their photodegradation capacity toward malachite green dye (MG). Different physical strategy to investigate the physiochemical behavior of the undoped and Mn doped V2O5. Using an aqueous malachite green (MG) solution and xenon light illumination, the degradation capabilities of the manufactured pristine and Mn doped V2O5 were studied. The pristine V2O5 and Mn doped V2O5 nanoarray display a photocatalytic efficiency of 94.79 % for MG compared to the pure V2O5 (75.52 %). Consistently, doping of Mn into V2O5 was shown to affect the photodegradation of malachite green significantly. Our finding suggests that Mn doped V2O5 nanomaterials act as potential photocatalysts to degrade the MG dye and can act as an environmental cleaner to resolve the other related issues.

Boosting the UV photo-detecting properties of V2O5 thin films by doping In3+ doping

In recent years, optoelectronic technology has demanded the development of efficient photodetectors by layered semiconductor materials at affordable prices. Herein, we put the efforts to generate V2O5 thin films on the surface of glass slides with diverse insertion of In content (0, 1, 2, 3, 4, and 5 wt%) via cost effective nebulizer spray pyrolysis technique and examined their application in U.V. photosensing. Standard characterization techniques are used for these films to identify the cause of In dopant on its morphological, structural, and opto-electrical properties. X-ray diffraction (XRD) plots confirm the development of single-phase orthorhombic structure grown along [010] direction, without the appearance of foreign phases. Further, the dopant ingredient (In) hikes the crystallinity and crystallite sizes (36–51 nm) up to a certain threshold level (2 wt%) and decreases it for further growing In doping. The Field emission scanning electron microscope (FESEM) images display homogeneous nanorods morphology formation at all doping levels. Doping improved its photon absorption in the U.V. region, and the bandgap obtained from the absorbance spectra tuned to a lower value of 1.98 eV up to 2 wt%. All the created thin films emit intense emission bands at 475 nm and 640 nm. Characterization involving I-V measurements under 365 nm illumination at 5 V bias exhibiting commendable performance in terms of photodetector metrics (Responsivity (R) = 7.96 × 10−1 AW−1, Detectivity (D*)=3.63 × 1011 Jones and External quantum efficiency (EQE) = 186 %) for 2 % In doped V2O5. The same sample exhibits a fast-rising /falling time up to 0.6s /0.7 s, respectively. Our results may widen the field of applications in high-performance U.V. photodetector.

The efficacy of rare-earth doped V2O5 photocatalyst for removal of pollutants from industrial wastewater

Photocatalysis is regarded as one of the most environmentally benign methods of mitigating the effects of textile wastewater. Despite the fact that various semiconducting metal oxides are used in photocatalysis, their performance is still insufficient. In this study, the hydrothermal method was used to synthesize rare-earth (RE) elements [Holmium (Ho) and Ytterbium (Yb)] doped vanadium pentoxide (V2O5) to improve its photocatalytic efficiency. The effect of RE ions on the photocatalytic efficiency of doped V2O5 has also been analyzed from both the experimental and first-principle density functional theory (DFT) methods. The stable orthorhombic crystal structure of doped V2O5 is confirmed by the X-ray diffraction with no secondary phase, and high-stressed conditions are generated for the 3 mol.%. The crystallite size, strain, and dislocation density are calculated to perceive the doping effect on the bare V2O5. The optical characteristics have been measured using UV–vis spectroscopy. The absorptions are found to be increased with increasing doping concentrations; however, the bandgap remains in the visible range. The photocatalytic properties are examined for the bare compound with varying pH, with the highest efficiency exhibited for pH 7. Moreover, it is observed that the RE ions significantly impact the catalytic behavior of V2O5. The degradation efficiency is improved by 93 % and 95 % for the 3 mol.% of Ho and Yb-doped V2O5 samples within 2 h, respectively, and the mechanism behind these extraordinary efficiencies has been explained thoroughly.

Engineering lattice oxygen defects and polaronic transport in vanadium pentoxide via isovalent phosphorus doping

Oxygen vacancies are equilibrium defects in the vanadium pentoxide system that give rise to polaronic hopping transport via V4+ charge compensating defect. In this paper, we report the tunability of polaron formation, the hopping process, and their magnetic signature by substitution of isovalent (5+) phosphorus ions in the V5+ site. The powder x-ray diffraction data show a monotonous shift in lattice parameters with progressive P-doping, confirming the presence of a substitutional dopant. The polaron hopping energy reduced from 0.307 to 0.290 eV depicting a lower defect concentration in P-doping in V2O5. At low temperatures, it is found to obey the Efros–Shklovskii variable range hopping mechanism. The estimated hopping range increased to 1.6 ± 0.1 nm in doped V2O5 in contrast to ∼1.3 nm in the undoped one. The electron spin resonance measurements show a diminishing broad ferromagnetic signal and rising paramagnetic signal (g = 1.97) with progressive P-doping depicting predominant isolated electronic spins in the doped sample. The same is corroborated in room temperature M–H with a distinct hysteresis that diminishes with P-doping and a rise of a paramagnetic slope. Moreover, the reduced oxygen defects and lower V4+ relative occupancy together with fermi level fall toward intrinsic position are substantiated by photoelectron emission studies.

Defect controlled diffusion of lithium ions in Mn doped V2O5 for potential applications as cathode material

With a motivation to unravel the effect of cation (Mn) doping-induced modifications in structure, charge transfer resistance, and Li-ion diffusion in V2O5 a systematic study using X-ray diffraction (XRD), Raman Spectroscopy and electrochemical impedance spectroscopy (EIS) has been employed using three electrodes configuration. Structural investigations using XRD suggest the selective diffusion of Mn ion towards the c-axis at a low doping percentage. Raman spectroscopy suggests the shift in 994 cm-1 modes which substantiates the uniaxial diffusion of Mn ions. Nyquist plots show that interfacial charge transfer resistance is highest for the lowest doping i.e., 1% Mn-doped V2O5 and exhibits the lowest diffusion coefficient as compared to other doped V2O5 samples. Specific capacitance calculated from cyclic voltammetry is found to be highest for the 4% Mn-doped V2O5 sample. Moreover, diffusion of Lithium ions improves with an increase in doping concentration due to higher concentration of defects as evident from Δd/d and Nelson–Riley factor (NRF) for pure V2O5 and Mn-doped V2O5.

Defect-Rich W/Mo-Doped V2O5 Microspheres as a Catalytic Host To Boost Sulfur Redox Kinetics for Lithium–Sulfur Batteries

It is very important to develop ideal electrocatalysts to accelerate the sulfur redox kinetics in both the discharging and charging processes for high-performance lithium-sulfur batteries. Herein, defect-rich cation-doped V2O5 yolk-shell microspheres are reported as a catalytic host of sulfur. The doping of W or Mo cations induces no impurities, broadens the lattice spacing of V2O5, and enriches the oxygen vacancy defects. Thus, the doped V2O5 host affords sufficient active sites for chemically anchoring polysulfides and promising catalytic effect on the mutual conversion between different sulfur intermediates. As a result, the S/W-V2O5 cathode delivers a discharging capacity of 1143.3 mA g-1 at an initial rate of 0.3 C and 681.8 mA g-1 at 5 C. Even under a sulfur loading of up to 5.5 mg cm-2 and a minimal electrolyte/sulfur ratio of 6 μL mg-1, the S/W-V2O5 cathode could still achieve good sulfur utilization and dependable cycle stability. Thus, this work offers an electrocatalytic host based on the cation doping strategy to greatly enhance the sulfur redox kinetics for high-performance Li-S batteries.

Recent advancement in doped vanadium pentoxide for energy storage devices

The search for high-performing supercapacitors is a major area of energy storage and conversion research due to the increasing demand for portable electronics, electric vehicles, and green energy solutions. To improve upon traditional batteries and capacitors, researchers have focused on designing different electrode materials made of vanadium pentoxide (V2O5), which has a high capacitive potential and is non-toxic. However, poor conductivity, low porosity, and charge/discharge dissolution limit the performance of bulk V2O5. To overcome these limitations, researchers have added dopants to V2O5, which increase electron mobility, surface area, and structural stability. This review focuses on the effects of different synthesis methods and physical treatment strategies on the structure and electrochemical performance of doped V2O5 electrodes.

Novel 2D sulfur-doped V2O5 flakes and their applications in photoelectrochemical water oxidation and high-performance energy storage supercapacitors

Development of high-performance energy storage devices with exceptional and consistent performance is of immense significance due to ecological concerns to meet the growing demands for high-performance energy conversion and storage. V2O5 materials have attracted particular attention for energy storage owing to their excellent Faradaic performance, several oxidation valences, inexpensive, ease of synthesis, and non-toxic, all of which make them favorable materials for both energy conversion and storage applications. In this investigation, an efforts has been made to synthesize the novel 2D S-doped V2O5 flakes via a facile hydrothermal procedure. The materials developed were utilized in photoelectrochemical (PEC) water oxidation as well as electrochemical energy storage supercapacitors. XRD analysis confirmed that V2O5 crystal structure is orthorhombic, and doping of the sulfur ions into V2O5 lattice, which has considerably narrowed the band gap from 2.17 eV to 2.02 eV. Nyquist plots revealed that the doped electrode showed reduced inner resistance (RS) and charge transmission resistance (RCT) compared to that of naked electrode. Density functional theory (DFT) calculations illustrate that sulfur-ion doping in the two-dimensional V2O5 monolayer remarkably enhances the electrical properties of the materials. Furthermore, the doping of S into the host matrix causes a positive influence on its structure, electrical conductivity and ion diffusion. Doped V2O5 2D flakes exhibited a specific capacitance of 749F/g at 1 A/g with excellent stability after 3000 cycles at 2.5 A/g compared to the undoped sample. Furthermore, 2D S-doped V2O5 flakes showed ∼ 4.7 folds improvement in photocurrent density and reduced charge resistance than the undoped sample, indicating that doped V2O5 has excellent photoelectrochemical (PEC) water oxidation properties. The fabricated 2D nanostructured materials can be the potential materials for constructing inexpensive and high-performance energy conversion (e.g., hydrogen production, green energy generation), and energy storage devices.

Cobalt-doped V2O5 hexagonal nanosheets for superior photocatalytic toxic pollutants degradation, Cr (VI) reduction, and photoelectrochemical water oxidation performance

The worldwide energy calamity and ecological disturbances demand materials that can remove harmful contaminants from the polluted water. Recently, semiconductor-based catalytic dye removal has created much consideration due to its high efficacy and eco-friendly contaminated water treatment processes. Vanadium oxide (V2O5) has attracted superior attention as a catalyst due to its robust oxidation power, chemical inertness, and stability against photodegradation. In this study, pristine and cobalt (Co)-doped V2O5 samples were synthesized by solvothermal method and examined for their photo-degradation activity and photoelectrochemical (PEC) water oxidation properties. The orthorhombic crystal phase was confirmed by X-ray diffraction (XRD), hexagonal-shaped morphology was observed by scanning electron microscope (SEM) and reduced optical band gap (2.01 eV) was noticed for doped V2O5 catalyst compared to the pristine (2.20 eV) catalyst. The doped V2O5 catalyst exhibited enhanced photodegradation of crystal violet CV (92.7%) and Cr (VI) reduction (90.5%) after 100 min of light irradiation. The doped photocatalyst exhibited approximately 2.1 and 1.9-fold enhancement of photodegradation of CV and Cr(VI) reduction, respectively. The doped electrode showed improved photocurrent density (0.54 mA/cm−2) compared to pristine electrode (0.12 mA/cm−2). Moreover, the doped electrode showed reduced charge-transfer resistance and enhanced charge-transfer properties compared to those of the pristine electrode. Hence, the prepared hexagonal-shaped V2O5 is a suitable material for the elimination of environmental contaminants from the polluted water as well as water splitting for hydrogen generation.

Highly efficient photodegradation of toxic organic pollutants using Cu-doped V2O5 nanosheets under visible light

Photodegradation of organic pollutants using metal oxides has shown extraordinary promise owing to the catalytic efficacy, low cost, less noxiousness, and good chemical constancy. In this research, pure and transition metal ions (Cu)-doped V2O5 nanosheets were synthesized and investigated for their photocatalytic efficiency using methyl blue (MB) and rhodamine B (RhB) organic dye pollutants under visible light irradiation. The orthorhombic crystal phase was confirmed by XRD analysis, which exhibited a stable phase upon incorporating Cu dopant ions. Optical properties were examined using optical absorption spectroscopy, while a reduced band gap was observed in the doped V2O5 nanosheets over the undoped sample. EIS analysis confirmed lower charge resistance in doped V2O5 nanosheets. The Cu dopant incorporation into the host matrix considerably enhanced photodegradation efficiency for MB and RhB impurities under light illumination. The improvement in catalytic efficacy is attributed to dopant ions that can separate photoinduced charge carriers and the quick movement of the charge. Moreover, comparatively lesser crystalline size, improved specific surface area, and hydroxyl group onto the catalyst surface are quite advantageous to offer better photocatalytic activity of Cu-doped V2O5 nanosheets.

Fabrication of reduced Graphene Oxide supported Gd3+ doped V2O5 nanorod arrays for superior photocatalytic and antibacterial activities

In the current report, pure V2O5, a series of Gd doped V2O5 (1 wt%, 3 wt%, 5 wt% and 10 wt%) and graphene integrated Gd–V2O5 photocatalysts have been prepared using a facile wet chemical approach. The effect of Gd+3 ions substitution and RGO support on V2O5 was studied by the different analytical techniques. X-ray diffraction (XRD) results showed the orthorhombic crystal structure of synthesized samples with crystallize size in range of 22–35 nm. Morphological analysis showed nanorods and nanorod arrays like appearance of V2O5, Gd–V2O5 and GdV-2O5/RGO, respectively. Gd–V2O5 and Gd–V2O5/RGO exhibited enhanced optical response in the visible region along with decrease in the band gap values for Gd doped V2O5 samples. BET surface area of Gd–V2O5 and Gd- V2O5/RGO was calculated as 12.39 g/m2 and 15.35 g/m2 that was found to be higher than pristine V2O5. To study the photocatalytic activity of synthesized photocatalysts, methylene blue (MB) was chosen as model pollutant. Among the Gd doped V2O5 samples, highest photocatalytic activity (45.62%) was achieved by optimal concentration of 5 wt% Gd–V2O5 that is accredited to effective separation of electron-hole pairs. While Gd–V2O5/RGO showed 2.1 times higher dye removal (97.12%) than unsupported Gd–V2O5, under the visible light irradiation. The significantly high photocatalytic activity of Gd–V2O5/RGO is due to the synergistic effect aroused by combined action of Gd+3 ions doping and advantageous properties of highly conductive and large surfaced graphene. Recycling experiments for V2O5 derivatives showed good stability and recyclability of photocatalysts. Additionally, Gd–V2O5/RGO was found to be more potential anti-bacterial agent than V2O5 and Gd–V2O5.

The Sensitivity of V2O5:Sm2O3 Thin Films against NO2 Toxic Gas

Vanadium oxide V2O5 thin films with variation doping ratios of Sm2O5 (2, 4, 6, and 8 % wt.) on corn glass and p- type silicon substrates were prepared by pulsed laser method. The X-ray diffraction peaks for V2O5 decreases with doping ratio of Sm2O3. FESEM images for V2O5 and doped thin films illustrates clusters with a homogeneous distribution in nano scale. The energy gap varied upon the increment of doping concentration, starting from 2.610 eV to 2.7 eV. Gas sensor measurement of pure and doped V2O5 demonstrated a sensitivity to NO2 gas, and the sensitivity expanded upon the increment of operation temperature. The greatest sensitivity was found to be about 99%, while best response time of 10s and recovery time of 18s were recorded using the 4% Sm2O3 sample at 50 °C.

Impact of Zn2+ Doping on the Structural, Morphological and Photodiode Properties of V2O5 Nanorods

In the present study, the effects of Zn2+ doping on the microstructural, morphological and photodiode response of the V2O5 nanorods have been studied. Pure and Zn2+ doped V2O5 nanorods were prepared by a simple and cost effective wet chemical solution process. The XRD studies confirmed that the pure and Zn2+ doped samples exhibit crystalline nature with mixed phases for Zn doping. From the morphology analysis, it is observed that substitution of Zn2+ into the V2O5 matrix is found to gradually transform the morphology from hexagonal face rods to short rods mixed with the plate like structures. The luminescence features of nanostructures are analyzed using photoluminescence studies. Moreover, the V2O5/p-Si and ZnV2O5/p-Si photodiodes parameters were studied under dark and light environments.

Fabrication of phenylhydrazine sensor with V2O5 doped ZnO nanocomposites

Herein, the V2O5 doped ZnO nanocomposites (NCs) were prepared by applying the wet-chemically (co-precipitation) technique in alkaline phase. The synthesized NCs were characterized in details by applying FESEM, XPS, EDS, TEM and XRD analysis. The doped V2O5 doped ZnO NCs were used to deposit in the form of thin layer on the glassy carbon electrode (GCE) by nafion binding agent (5% in ethanol) to result the desire electrochemical sensor selective to phenylhydrazine (PHyd). Plotting current versus concentration, a linear relation was established known as the calibration curve of PHyd sensor. Applying the regression-coefficient (R2 = 0.9936) on the calibration curve, the detection range of PHyd categorized by linear dynamic range (0.01 mM–0.1 nM) is evaluated. The sensor sensitivity (12.389 μAμM−1cm−2) using the calibration curve slope and GCE (0.0316 cm2) cross-sectional area is recognized. Finally, the lower limit for the detection (96.31 ± 4.82 pM) is calculated from signal-to-noise ratio at 3. From the detail investigation, the sensor was found as proficient in the term of reproducibility, long-term performing ability and response time. Furthermore, the collected samples from the various sources of environment and extracted were assessed for the practical validity of the sensor and found as satisfactory.

Structural and Morphological Charactrization of Nd Doped V2o5 Nanorods

V2O5 And Nd:V2O5 Nanorods Were Prepared By Using Low Cost Sol-Gel Method And The Synthesized Samples Were Analyzed Through XRD, SEM And HRTEM Techniques. The Structural Analysis Of The Processed V2O5 And Nd:V2O5 Samples Are Exhibited In The Form Of Orthorhombic V2O5 Phase. The SEM And HRTEM Images Of The Nd:V2O5 Sample Are Shown That The V2O5 Nonoparticles Appeared As Nonorods With Smooth Surface In Which Nd Spherical Particles Are Decorated.

Enhanced reversible lithium storage property of Sn0.1V2O5 in the voltage window of 1.5–4.0 V

Sn4+ doped V2O5 (Sn0.1V2O5) sample was synthesized by a sol-gel method and post annealing at 400 °C for 1 h in air. The microstructure of the as-prepared the Sn0.1V2O5 was analyzed by XRD, XPS, and SEM. The lithium storage performance of the Sn0.1V2O5 was characterized by CV, EIS, and charge/discharge tests in the voltage window of 1.5–4.0 V (vs. Li/Li+). The results demonstrated that Sn doping can refine the grain size of V2O5, increase V4+ concentration in Sn0.1V2O5, and favor the formation of two-dimensional sheet-like morphology. Compared to undoped V2O5, the Sn0.1V2O5 exhibited significantly enhanced lithium storage performance in the voltage window of 1.5–4.0 V (vs. Li/Li+). For example, after 100 cycles at 200 mA g−1, the Sn0.1V2O5 retained a specific discharge capacity of 135 mAh g−1, much higher than that (91 mAh g−1) of the pure V2O5. In addition, Sn0.1V2O5 exhibited a higher initial coulombic efficiency (98.16%) than the undoped V2O5 (91.05%). The improved lithium storage performance can be attributed to the increased lithium ion diffusion coefficient, enhanced electrochemical reaction reversibility, and decreased electrochemical reaction resistance upon Sn4+ doping.

Structural and Morphological Properties of Boron Doped V2O5 Thin Films: Highly Efficient Photocatalytic Degradation of Methyl Blue

Boron doped vanadium thin films were fabricated on the micro-slide glass substrates by spray pyrolysis technique at substrate temperature of 400°C. Initially, 0.1 M vanadium(III) chloride (VCl3) solution was prepared in ethanol: water mixture (1: 4) solvent. To prepare the boron doped vanadium oxide films as the concentrations of 2, 5, 7, 10, 20%, the suitable amount of H3BO3 was added in 0.1 M VCl3 solution for each of the samples. X-Ray diffraction experiment with the produced films showed that tetragonal β-V2O5 phases formed. The synthesized boron-doped V2O5 thin films having the large surface area demonstrated the efficient catalytic properties in the photocatalytic degradation of methyl blue in water samples under Xenon light. The photocatalytic reaction efficiency was measured by recording the decrease of absorbance at 590 nm in UV-Vis absorption spectra. The methyl blue dye was degradated in approximately 30 min. The photocatalytic experiment results of the produced thin films showed that boron doping amount positively effects the degradation efficiency and reaction time.

Tuning the optical bandgap of V2O5 nanoparticles by doping transition metal ions

Abstract In this study the influence of transition metal ions doping on optical properties of V2O5 nanoparticles is investigated. The shift in absorption edge caused by the dopant is analyzed from the UV-visible absorption spectra. The absorption edge of Ti doped V2O5 nanocrystals is shifted to longer wavelength region, while that of Zr doped V2O5 showed a blue shift. Ti doped V2O5 nanocrystal in spite of its large crystallite size showed improved optical properties and its optical bandgap (1.96 eV) is less than un-doped V2O5 (2.2 eV). This is attributed to lattice expansion by Ti ion and formation of oxygen vacancies within the bandgap. The oxygen vacancies acts as intermediate energy states and reduce the optical bandgap. However, the PL spectra of Ti-doped V2O5 did not exhibited emission peak corresponding to oxygen vacancies due to high crystallinity. The life time of excitons in excited state is investigated from time resolved PL decay. The excitons in doped sample showed tri-exponential decay whereas in pure sample they exhibited bi-exponential decay. The average lifetime of excitons in doped V2O5 is higher than pure V2O5 sample. This study reveals that by optimizing the concentration of Ti and Zr dopant ions in V2O5 lattice, its energy band structure can be tailored for photovoltaic, catalytic and photoluminescence applications. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Nanotechnology: Ideas, Innovations & Initiatives-2017 (ICN:3i-2017).

Influence of Al doping on structural, luminescence and electrochemical properties of V2O5 nanostructures synthesized via non-hydrolytic sol-gel technique

Phase pure and Al3+ doped vanadium pentoxide nanostructure materials (AlxV(2-x)O5(x = 0, 0.01, 0.03 and 0.05)) have been synthesized by surfactant-free non-hydrolytic sol-gel route. The effect of dopant concentration on structural, morphological, elemental, luminescence and electrochemical properties was studied for the prepared samples. XRD analysis shows that all the samples possess orthorhombic structure in nature. HRSEM and HRTEM images of Al3+ doped V2O5 nanostructures revealed the morphology of self-assembled nanorods. The presence of elements, V, Al and O with their oxidation states was ensured by FTIR, EDXS and XPS analyses. The DRS-UV–vis and PLE spectral analyses exhibit that the optical band gap of Al:V2O5 nanostructure materials increases with increase in dopant concentration. The CV results reveal that the product has a better cyclic performance and might act as a primary cathode material for high energy density secondary lithium ion batteries.

Highly sensitive optical ammonia gas sensor based on Sn Doped V2O5 Nanoparticles

Herein, we present the synthesis, characterization and optical ammonia gas sensing of pure and Sn-doped vanadium oxide (V2O5) nanoparticles prepared by the sol-gel process. The V2O5 nanoparticles were doped with Sn concentrations of 2 wt%–6 wt%, and characterized using X-ray diffraction, atomic force microscopy, UV–vis spectroscopy and photoluminescence spectroscopy which confirmed the orthorhombic crystal structure. The crystalline size was found to decrease with enhancing the doping concentrations of Sn. The lattice-strain and crystalline size with the peak-broadening of pure and Sn doped V2O5 nanoparticles were analyzed by William-Hall (W-H) method and size-strain plot. The UV–vis absorption showed a decrease in the energy band gap (3.27 eV–3.07 eV) with an increase in the Sn doping concentration. The Sn-doped V2O5 nanoparticles were used to detect ammonia gas (5–50 ppm) through photoluminescence based detection method. Interestingly, it was observed that the optical response for the 2 wt% Sn doped V2O5 nanoparticles was maximum (77.84%) towards 50 ppm ammonia compared to other V2O5nanoparticles based samples.