V2O5 Nanorods Research Articles

Strategically Modulating Proton Activity and Electric Double Layer Adsorption for Innovative All-Vanadium Aqueous Mn2+/Proton Hybrid Batteries.

Aqueous Mn-ion batteries (MIBs) exhibit a promising development potential due to their cost-effectiveness, high safety, and potential for high energy density. However, the development of MIBs is hindered by the lack of electrode materials capable of storing Mn2+ ions due to acidic manganese salt electrolytes and large ion radius. Herein, the tunnel-type structure of monoclinic VO2 nanorods to effectively store Mn2+ ions via a reversible (de)insertion chemistry for the first time is reported. Utilizing exhaustive in situ/ex situ multi-scale characterization techniques and theoretical calculations, the co-insertion process of Mn2+/proton is revealed, elucidating the capacity decay mechanism wherein high proton activity leads to irreversible dissolution loss of vanadium species. Further, the Grotthuss transfer mechanism of protons is broken via a hydrogen bond reconstruction strategy while achieving the modulation of the electric double-layer structure, which effectively suppresses the electrode interface proton activity. Consequently, the VO2 demonstrates excellent electrochemical performance at both ambient temperatures and -20°C, especially maintaining a high capacity of 162mAhg-1 at 5Ag-1 after a record-breaking 20000 cycles. Notably, the all-vanadium symmetric pouch cells are successfully assembled for the first time based on the "rocking-chair" Mn2+/proton hybrid mechanism, demonstrating the practical application potential.

Robust Dual-Color Electrochromism of Vanadium Oxide Nanorods Embedded on Reduced Graphene Oxide: Unraveling the Mechanism

Vanadium pentoxide (V2O5), associated with both cathodic and anodic coloration, is considered as one of the best electrochromic (EC) materials for energy-saving smart electronics. Here we present the fabrication and detailed mechanism analysis for improving the electrochromic properties of V2O5 incorporated in a reduced graphene oxide (rGO) matrix using a facile wet chemical method. The microstructural study disclosed the formation of prominent V2O5 nanorods embedded in the rGO matrix. The optimized electrochromic film resulted in coloration (tc) and bleaching time (tb) of ∼6.2 and ∼4.8 s, respectively, much faster than the color switching kinetics of the pristine V2O5 sample (tc ∼ 19.4 s, tb ∼ 15.3 s). The more dispersed structure also ensured an approximate 400% enhancement in the optical modulation of EC film and reflected a noticeable improvement in the coloration efficiency (∼347 cm2/C) of V2O5 film. Modification with rGO resulted in an outstanding improvement in the electrochemical redox stability of V2O5 up to 5000 CV cycles with minimum deterioration in the curve area. The formation of nanorod structure was the prime factor for better ion diffusion and thereby facilitating enhanced performance.

The excellent infrared radiation regulation ability of VO2 nanorods

Dynamic infrared radiation has significantly contributed to thermal comfort by adaptively radiating heat into space without necessitating external energy consumption. This study introduces a novel approach to fabricate dynamic infrared radiation-regulated materials using VO2 nanorods. The VO2 nanorods were synthesized via a conventional hydrothermal method. XRD and SEM analyses confirmed the high crystallinity and uniform size of the VO2 nanorods. HRTEM measurements revealed that the nanorods had an approximate length of 1 μm and a width of 100 nm. These nanorods were combined with KBr and pressed into a tablet form. Subsequent thermal imaging was conducted to assess their dynamic infrared radiation regulation capability. Remarkably, the optimized variation in emissivity for the VO2-based tablets reached up to 0.46. And the Mie scattering theory was used to interprete the insight mechanism. It seems that the Qabs of VO2 nanorod before and after phase transition dominate the dynamic infrared radiation regulation ability at different temperatures. This finding offers a novel, straightforward, and highly efficient energy-saving solution for thermal management systems.

Capacitive attribute of vanadium-oxide embedded activated charcoal composite

This paper reports the study of hydrothermally synthesized coconut charcoal (EDL material) and vanadium-oxide (pseudocapacitive material) based composite material. SEM and TEM studies reveal the formation of embedded V2O5 nanorods (NRs) in the presence of activated charcoal (AC). Whereas, the formation of nanosheet (NSs) morphology of V2O5 was explained based on Ostwald ripening. Embedded V2O5 nanorods (NRs) in AC could be revealed in the form of the blurred dotted electron diffraction pattern of CS-AC/V2O5 NRs, indicating the presence of crystalline and amorphous phases at a point simultaneously in the composite. The VO, O–V‒O signatures observed in RAMAN and FTIR studies indicate the presence of the α phase of V2O5 NSs and NRs. An enhanced diffusion coefficient for CS-AC/V2O5 NRs compared to V2O5 NSs was observed; a decreased total resistance for CS-AC/V2O5 NRs compared to CS-AC was also noted. A characteristic of stable specific capacitance was observed at various current levels of this composite compared to the specific capacitances of coconut shell-based charcoal and vanadium oxide.

Reinforcing the photocatalytic removal of ibuprofen antibiotic over S-scheme 2D/1D Bi12O17Cl2/V2O5 heterojunction under solar light illumination

In our work, the Bi12O17Cl2/V2O5 hybrid with a favorable S-scheme mechanism was prepared via a simple self-assembly procedure for ibuprofen (IBF) oxidation under solar light energy. The 2D Bi12O17Cl2 provides abundant active sites to immobilize 1D V2O5 nanorods, enhancing the interaction between two semiconductors. The establishment of the 2D/1D structure reflected a positive effect on the surface area of Bi12O17Cl2/V2O5-10 %, which was linked to the reduction in the aggregation rate of V2O5 nanorods. Amazingly, optimal Bi12O17Cl2/V2O5 photocatalysts achieved exceptional IBF degradation capacities of 88.6 % and 71.3 % under LED and direct solar light irradiation, respectively. Among the samples, the optimized Bi12O17Cl2/V2O5-10 % reflected the best IBF oxidation kinetic with a reaction constant of 0.03894 min− 1, which is stronger than pristine Bi12O17Cl2 (0.00885 min− 1) and V2O5 (0.0119 min− 1) by 4.4 and 3.27 times, respectively. The promoted catalytic activity was correlated to the S-scheme heterojunction between Bi12O17Cl2 and V2O5 that could upgrade the solar light absorbance, facilitate the separation and transportation of charge carriers, and strengthen the redox potential of Bi12O17Cl2/V2O5. Furthermore, the parameters revealed the best IBF treatment at a catalyst dosage of 0.6 g/L and a pH value of 7. Besides, Bi12O17Cl2/V2O5-10 % recorded outstanding catalytic stability in six cycles without notable alteration in its structure, morphology, or optical properties. On the other hand, the radical quenching tests declared that •O2− and •OH play major contributions in IBF photooxidation over Bi12O17Cl2/V2O5-10 %. Finally, our work offers vital guidance towards designing robust bismuth-based heterojunctions for efficient degradation of IBF antibiotics in a sustainable and cost-effective strategy.

Rational design of V2O5 nanorod anchored carbon microsphere cathode materials for improved-performance lithium-ion batteries

Rational design of V2O5 nanorod anchored carbon microsphere cathode materials for improved-performance lithium-ion batteries

Insights into the photocatalytic and supercapacitor performance of V2O5 nanorods synthesized by green synthetic approach using Epipremnum aureum leaves extract

Insights into the photocatalytic and supercapacitor performance of V2O5 nanorods synthesized by green synthetic approach using Epipremnum aureum leaves extract

Substantial Electrocatalytic Oxygen Evolution Performances of Activated Carbon-Decorated Vanadium Pentoxide Nanocomposites

Developing the ecofriendly and high-fidelity electrocatalysts for the oxygen evolution reaction (OER) is essential to foster effective production of environmentally friendly hydrogen. Herein, we fabricated the highly efficient OER electrocatalysts of the activated carbon-decorated vanadium pentoxide (AC-V2O5) nanocomposites using a facile hydrothermal technique. The AC-V2O5 nanocomposites displayed an aggregated structure of the AC nano-sheet-anchored orthorhombic V2O5 nanorods. When performing the OER process in an alkaline electrolyte at 10 mA/cm2, AC-V2O5 exhibited the low overpotential (~230 mV), small Tafel slope (~54 mV/dec), and excellent stability. These substantial OER performances of AC-V2O5 could be ascribed to the synergistic effects from both the electrochemically active V2O5 nanorods and the highly conductive AC nanosheets. The results infer that the AC-V2O5 nanocomposites possess a substantial aptitude as a high-performance OER electrocatalyst for production of the future green energy source—hydrogen.

Solvothermal Guided V2O5 Microspherical Nanoparticles Constructing High-Performance Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries have attracted a lot of attention owing to their cost effectiveness and plentiful resources, but less research has been conducted on the aspect of high volumetric energy density, which is crucial to the space available for the batteries in practical applications. In this work, highly crystalline V2O5 microspheres were self-assembled from one-dimensional V2O5 nanorod structures by a template-free solvothermal method, which were used as cathode materials for zinc-ion batteries with high performance, enabling fast ion transport, outstanding cycle stability and excellent rate capability, as well as a significant increase in tap density. Specifically, the V2O5 microspheres achieve a reversible specific capacity of 414.7 mAh g-1 at 0.1 A g-1, and show a long-term cycling stability retaining 76.5% after 3000 cycles at 2 A g-1. This work provides an efficient route for the synthesis of three-dimensional materials with stable structures, excellent electrochemical performance and high tap density.

VO2 nano-rod coated mica composite pearlescent pigment for temperature control packaging

A temperature control mica/VO2 functional pearlescent pigment was designed for the packaging industry. Firstly, a layer of VO2 nanorod film was coated on the surface of flake mica powder by hydrothermal method. Then, the surface of pure mica was modified by silane coupling agent KH-570 and sandwiched between inorganic powders to strengthen the combination. Secondly, the mica/VO2 composite pearlescent powder with gray-green pearlescent effect were successfully obtained by thermal annealing. The crystal structure of the VO2 coating and the chemical valence state of vanadium were verified by X-ray diffraction and X-ray photoelectron spectroscopy. Finally, powders were mixed with polyurethane resin to obtain a functional film. The infrared transmittance of film at 28 °C and 70 °C showed that the composite film with mica content of 3 g had greater temperature control properties, and the difference between high and low temperature transmittance was about 16%. Most importantly, the shiny decorative effect of pearlescent pigment can be still be maintained after being endowed with temperature control property. This work proposes the preparation of functional mica/VO2 composite with pearlescent effect and temperature control property.

High-performance VO2/CNT@PANI with core–shell construction enable printable in-planar symmetric supercapacitors

As a progressive electronic energy storage device, the flexible supercapacitor holds tremendous promise for powering wearable/portable electronic products. Of various pseudocapacitor materials, vanadium dioxide (VO2) has garnered extensive attention due to its impressive theoretical capacitance. However, the challenges of inferior cycling life and lower energy density to be addressed. Herein, we prepare VO2 nanorods with winding carbon nanotubes (CNT) via a facile solvothermal route, followed by in situ polymerization of polyaniline (PANI) shell. Taking full advantage of the synergistic effect, the VO2/CNT@PANI composite delivers a high specific capacitance of 354.2F/g at 0.5 A/g and a long cycling life of ∼ 88.2 % over 5000 cycles resulting from the enhanced conductivity of CNT and stabilization of PANI shell. By screen printing the formulated inks with outstanding rheological behaviours, we manufacture an in-planar VO2/CNT@PANI symmetric supercapacitor (VO2/CNT@PANI SSC) device featuring an orderly arrangement structure. This device yields a remarkable areal energy density of 99.57 μWh/cm2 at a power density of 387.5 μW/cm2 while retaining approximately ∼ 87.6 % of its initial capacitance after prolonged use. Furthermore, we successfully powered a portable game machine for more than 2 min using two SSCs connected in series with ease. Therefore, this work presents a universal strategy that utilises combination and coating to boost electrochemical performance for flexible high-performance supercapacitors.

Synthesis and Characterization of V2O5 Nanorods Using Hydrothermal Method for Energy Application

Background: Nanomaterials are very useful in energy harvesting and energy storage devices. Morphological features play a vital role in energy storage devices. Supercapacitors and batteries are examples of energy storage devices. The working of a supercapacitor is decided by the nature of the microstructure and other features of the electrode material. Vanadium Pentaoxide (V2O5) is one of the promising materials due to its attractive features, such as band gap, multiple oxidation state, and large conductivity transition from semiconducting to conducting domain. Objective: This study aimed to perform the tuning of structural, optical and morphological properties of V2O5 nanomaterials using the hydrothermal method. Methods: A low-cost hydrothermal method was used in this work. Hydrothermal synthesis was carried out at different concentrations of Ammonium Metavanadate (NH4VO3), varying from 0.06 M, 0.08 M, and 0.1 M in the aqueous medium. Moreover, the pH of the solution was maintained at 4 using drop-wise addition of H2SO4. Hydrothermal synthesis was carried out at 160° for 24 hours. The synthesized precipitate was annealed at 700° for 7 hours in ambient air. Structural, optical, morphological, and elemental probing was carried out. Result: XRD revealed the formation of monoclinic crystalline phase formation of V2O5. Crystallite size increased with an increase in the concentration of vanadium precursor. The band gap obtained using UV-Vis spectroscopy decreased upon an increase in concentration. SEM micrographs displayed nanosheet and nanorod-like distorted morphology. The presence of vanadium and oxygen was noticed in the EDS study. Conclusion:: Nanoparticles with attractive features are very useful as an electrode material for supercapacitors. Upon changing concentration, we can change the band gap of the material, adding an extra edge in the use of these materials.

Disorder/order-heterophase VO2 for enhanced lithium storage performance in lithium-ion capacitors

Interfacial engineering has proved to be an effective strategy for improving the performance of electrode materials in many applications. Herein, we report the disorder-order engineering of VO2 nanorods, and construct a crystal core and a surface-amorphized shell heterostructure (denoted as A-VO2) by simple hydrothermal method and reduction reaction, as a promising anode of lithium ion capacitor (LIC). The tunable amorphous layer introduces a large number of oxygen vacancy, which can efficiently improve electronic conductivity and enhance Li ion storage capacity. The crystalline-amorphous heterointerface generated in A-VO2 can significantly reduce the surface energy of VO2 and Li+ diffusion barrier, as well as increase the charge storage sites. The crystalline-amorphous heterogeneous phases work synergistically to facilitate ion and electron transport and maintain structural stability in discharge/charge process. The A-VO2-2 nanorods electrode possesses high capacity of 309 mAh g−1 at 0.1 A g−1 after 300 cycles, obviously larger than the crystalline VO2 electrode. In addition, the LIC, assembled with A-VO2-2 nanorods as anode and commercial active carbon (AC) as cathode, exhibit great energy density of 76.75 and 22.05 W h kg−1 at power density of 195 and 9360 W kg−1. It can remain 38.9 % of the initial capacity after 5000 cycles, demonstrating an instructive paradigm for disorder-order engineering in LIC electrode materials.

Solvothermal synthesis of VO2 nanoparticles with locally patched V2O5 surface layer and their morphology-dependent catalytic properties for the oxidation of alcohols.

Vanadium oxides are promising oxidation catalysts because of their rich redox chemistry. We report the synthesis of VO2 nanocrystals with VO2(B) crystal structure. By varying the mixing ratio of the components of a binary ethanol/water mixture, different VO2 nanocrystal morphologies (nanorods, -urchins, and -sheets) could be made selectively in pure form. Polydisperse VO2(B) nanorods with lengths between 150 nm and a few micrometers were formed at large water : ethanol ratios between 4 : 1 and 3 : 2. At a water : ethanol ratio of 1 : 9 VO2 nanosheets with diameters of ∼50-70 nm were formed, which aggregated to nano-urchins with diameters of ∼200 nm in pure ethanol. The catalytic activity of VO2 nanocrystals for the oxidation of alcohols was studied as a function of nanocrystal morphology. VO2 nanocrystals with all morphologies were catalytically active. The activity for the oxidation of benzyl alcohol to benzaldehyde was about 30% higher than that for the oxidation of furfuryl alcohol to furfural. This is due to the substrate structure. The oxidation activity of VO2 nanostructures decreases in the order of nanourchins > nanosheets > nanorods.

High-sensitivity NH3 gas detection at room temperature using In2O3 nanoparticles-modified VO2(B) nanorods heterojunction

In2O3 nanoparticles-modified VO2(B) nanorods heterojunction was proposed to improve the NH3 sensing performance at room temperature (25 ℃). VO2(B) nanorods were prepared by hydrothermal method and modified with In2O3 nanoparticles through chemical deposition and annealing. The effect of annealing temperature on microstructure and NH3 sensing performance was investigated. The morphology and crystal structure of the composite structure were characterized using SEM, TEM, and XRD. The results show that In2O3 nanoparticles with a diameter of 20–25 nm were uniformly distributed on the surface of VO2(B) nanorods when the annealing temperature was 400 ℃. Room temperature NH3 sensing performance was tested for six concentrations (1–100 ppm). Results showed that samples annealed at 400 ℃ exhibited the highest sensitivity, with a response value of up to 92 for 100 ppm NH3. This excellent sensing performance can be attributed to the excitation of electrons in narrow bandgap semiconductor VO2(B) at room temperature and the surface modification by In2O3 nanoparticles, which promote the adsorption of surface oxygen. Density functional theory indicated the composite structure has lower NH3 adsorption energy compared to VO2(B) and In2O3. A possible sensing mechanism combined heterojunction effect with hydroxylization effect was proposed to explain the sensing enhancement for composite structure.

Decorating carbon quantum dots onto VO2 nanorods to boost electron and ion transport kinetics for high–performance zinc–ion batteries

Rechargeable aqueous Zn–ion batteries (RAZIBs) are regarded as attractive alternatives for large–scale energy storage. V–based cathode materials have gained great attention due to the merits of rich valence states, controllable morphology, diverse crystal structures, and controllable chemical compositions. However, the development of high–performance V–based cathode is still impeded by sluggish electron/ion transport kinetics. To address this issue, this work reveals that the electrochemical performance of the VO2 cathode can be significantly boosted by decorating carbon quantum dots (CQDs) onto the VO2 nanorods via a facile hydrothermal reaction. The VO2/CQDs sample is characterized to have strong interface interaction with the presence of CO bond. Compared to the CQD–free counterpart, the obtained VO2/CQDs sample exhibits higher specific surface area (18.7 vs 4.4 m2 g−1), better electrolyte wettability (53° vs 114° for contact angle), reduced charge–transfer resistance (1.8 vs 19.9 Ω), and facilitated ion diffusion coefficient (1.66 × 10−10 vs 4.56 × 10−11 cm2 s−1). Benefiting from these features, a high attainable capacity of 427 mAh g−1 at 0.2 A g−1 can be reached for VO2/CQDs, corresponding to the specific energy of 333 Wh kg−1 (based on the mass of VO2/CQDs). When the current density increases to 8 A g−1, VO2/CQDs can still deliver 309 mAh g−1, showing great promise for high–rate capability. Moreover, the VO2/CQDs cathode renders stable cycle performance with retaining 229 mAh g−1 after 2000 cycles. By contrast, the unmodified sample demonstrates moderate electrochemical performance (373 and 186 mAh g−1 at 0.2 and 8 A g−1, respectively). The results highlight the importance of the CQDs decoration strategy, which can effectively boost electron/ion transport in oxide–based cathodes for high–performance RAZIBs.

Development of V2O5@GO (1D/2D) nanohybrid based chemiresistor for low-trace of toluene

A room temperature operated V2O5 nanorods-decorated graphene oxide (GO) nanosheets-nanocomposite based chemiresistor has been fabricated for detecting low-trace of toluene (5–60 ppm). The V2O5 nanorods were grown on GO nanosheets via hydrothermal method. The surface morphological investigation done by SEM and confirmed the decoration of V2O5 nanorods on GO nanosheets. The Rietveld refinement was performed for structural analysis of V2O5 nanorods confirmed the orthorhombic phase structure. At lowest concentration of 5 ppm, the sensor response of V2O5 @GO nanohybrid was 4.90 which was 2.84 and 3.52 times higher than pure GO and V2O5, respectively. The rapid response and recovery time at 5 ppm were observed to be 4.18 s and 5.86 s, respectively. The decoration of V2O5 nanorods on GO nanosheets increased the activated sites and formed p-n heterojunction, resulting in the enhanced sensing performance. The sensor response for the maximum concentration of 60 ppm was 36.25. Also, the V2O5@GO chemiresistor demonstrated high long-term stability and selectivity towards toluene as compared to other interfering volatile organic compounds such as, methanol, ethanol, aniline, formaldehyde, benzene, and acetone. This work opens a novel window for the development of devices that are room temperature operatable, highly sensitive and selective for rapid detection of toluene gas for its commercialization.

Building Low-Cost, High-Performance Flexible Photodetector Based on Tetragonal Phase VO2 (A) Nanorod Networks.

We present a straightforward and cost-effective method for the fabrication of flexible photodetectors, utilizing tetragonal phase VO2 (A) nanorod (NR) networks. The devices exhibit exceptional photosensitivity, reproducibility, and stability in ambient conditions. With a 2.0 V bias voltage, the device demonstrates a photocurrent switching gain of 1982% and 282% under irradiation with light at wavelengths of 532 nm and 980 nm, respectively. The devices show a fast photoelectric response with rise times of 1.8 s and 1.9 s and decay times of 1.2 s and 1.7 s for light at wavelengths of 532 nm and 980 nm, respectively. In addition, the device demonstrates exceptional flexibility across large-angle bending and maintains excellent mechanical stability, even after undergoing numerous extreme bending cycles. We discuss the electron transport process within the nanorod networks, and propose a mechanism for the modulation of the barrier height induced by light. These characteristics reveal that the fabricated devices hold the potential to serve as a high-performance flexible photodetector.

Phase-Stabilized Crystal Etching to Unlock An Oxygen-Vacancy-Rich Potassium Vanadate For Ultra-Fast Zn Storage.

Despite holding the advantages of high theoretical capacity and low cost, the practical application of layered-structured potassium vanadates in zinc ion batteries (ZIBs) has been staggered by the sluggish ion diffusion, low intrinsic electronic conductivity, and unstable crystal structure. Herein, for the first time, a phase stabilized crystal etching strategy is proposed to innovate an oxygen-vacancy-rich K0.486 V2 O5 nanorod composite (Ov-KVO@rGO) as a high-performance ZIB cathode. The in situ ascorbic acid assisted crystal etching process introduces abundant oxygen-vacancies into the K0.486 V2 O5 lattices, not only elaborately expanding the lattice spacing for faster ion diffusion and more active sites due to the weakened interlayer electrostatic interaction, but also enhancing the electronic conductivity by accumulating electrons around the vacancies, which is also evidenced by density functional theory calculations. Meanwhile, the encapsulating rGO layer ably stabilizes the K0.486 V2 O5 crystal phase otherwise is hard to endure subject to such a harsh chemical etching. As a result, the optimized Ov-KVO@rGO electrode delivers record-high rate capabilities with 462 and 272.39mAhg-1 at 0.2 and 10Ag-1 , respectively, outperforming all previously reported potassium vanadate cathodes and most other vanadium-based materials. This work highlights a significant advancement of layer-structured vanadium based-materials towards practical application in ZIBs.

Molybdenum-optimized electronic structure and micromorphology to boost zinc ions storage properties of vanadium dioxide nanoflowers as an advanced cathode for aqueous zinc-ion batteries

Recently, vanadium dioxide (VO2) has been recognized as one of the most prospective cathodes for aqueous zinc ion batteries (AZIBs) for its high reversible specific capacity; nevertheless, its Zn2+ diffusion kinetics and cycling stability have not yet met expectations. Herein, Mo ions are introduced into VO2 to optimize the intrinsic electronic structure and micromorphology of VO2, achieving significantly enhanced zinc-ion storage. It is found that the substitution of Mo for V narrows the band gap of VO2 and thus enhances the conductivity of the material, while VO2 nanorods are transformed into VO2 nanoflowers which are self-assembled from ultra-thin nanosheets after the introduction of Mo, exposing much more active sites to enhance the migration kinetics of Zn2+. Consequently, the Mo-substituted VO2 (0.5-Mo-VO2) exhibits excellent electrochemical properties, presenting a high initial capacity of 494.5 mAh/g at 0.5 A/g, excellent rate capability of 336 mA h g−1 at 10 A/g and brilliant cycling stability with the capacity retention of 82% over 2000 cycles at 10 A/g. This work provides significant guidance for the design of advanced cathodes for AZIBs by optimizing the electronic structure and tailoring morphology of V-based materials.