V2O5 Nanosheets Research Articles

Sn-Doped Hydrated V2O5 Cathode Material with Enhanced Rate and Cycling Properties for Zinc-Ion Batteries

Water molecules and cations with mono, binary, and triple valences have been intercalated into V2O5 to significantly improve its electrochemical properties as a cathode material of zinc-ion batteries. Sn as a tetravalent element is supposed to interact aggressively with the V2O5 layer and have a significant impact on the electrochemical performance of V2O5. However, it has been rarely investigated as a pre-intercalated ion in previous works. Hence, it is intriguing and beneficial to develop water molecules and Sn co-doped V2O5 for zinc-ion batteries. Herein, Sn-doped hydrated V2O5 nanosheets were prepared by a one-step hydrothermal synthesis, and they demonstrated that they had a high specific capacity of 374 mAh/g at 100 mA/g. Meanwhile, they also showed an exceptional rate capability with 301 mAh/g even at a large current density of 10 A/g, while it was only 40 mAh/g for the pristine hydrated V2O5, and an excellent cycling life (87.2% after 2500 cycles at 5 A/g), which was far more than the 25% of the pure hydrated V2O5. The dramatic improvement of the rate and cycling performance is mainly attributed to the faster charge transfer kinetics and the enhanced crystalline framework. The remarkable electrochemical performance makes the Sn-doped hydrate V2O5 a potential cathode material for zinc-ion batteries.

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.

Minimized optical scattering of MXene-derived 2D V2O5 nanosheet-based electrochromic device with high multicolor contrast and accuracy

An electrochromic device (ECD) based on the redoxation of the transition metal oxide (TMO) is a key technology for obtaining a stable and efficient color display. Developing the TMO-based electrochromic layer in a complex nanotexture can effectively acquire additional surface redox sites for improved ECD performance, while the increased roughness compensates the color range and accuracy through the excessive scattering effect. In this paper, we report the fabrication of a two-dimensional (2D) V2O5 nanosheet through the oxidation of single-layer V2CTx MXene. Benefitting from the high aspect-ratio morphology, the 2D V2O5 nanosheet-based electrochromic layer was fabricated in the optimized nanotexture with significantly reduced number of scattering sites such as surface roughness and internal voids, while acquiring large ion capacitance. The 2D V2O5 nanosheet-based ECD exhibited vibrant multicolor transformation with excellent optical contrast (53.98 %), response time (6.5 s for coloration and 5.0 s for bleaching) and coloration efficiency (91.1 cm2 C−1), which were far more superior to those obtained from a commercial V2O5 powder. In our study, we provide a new perspective based on optical engineering for designing electrochromic materials with the desired color variations.

Vanadium pentoxide–dibismuth trioxide nanosheets for efficient photoelectrochemical water splitting: Effect of applied bias on charge transfer kinetics

V2O5-Bi2O3 nanosheets were synthesized using a facile technique, and the effects of the heterostructure on the generation of photocurrents and charge kinetics under dark/light conditions were investigated. The intimate interfacial interaction between V2O5 and Bi2O3 in the V2O5–Bi2O3 nanosheets resulted in a significantly high and stable photocurrents of approximately 1.7 × 10-4 Acm−2 for 1000 s, which is 5.4 and 14.4 times higher than that of pure V2O5 and Bi2O3 nanosheets. The synergetic effect of pure V2O5 and Bi2O3 on the charge transfer kinetics of V2O5–Bi2O3 photoelectrodes at different applied bias potentials was systematically analyzed.

Preparation of free-standing V2O5 nanosheets for ammonia sensing application: A potential candidate for flexible sensors

Advances in the healthcare sector have driven tremendous possibilities as well as the necessity in developing potential innovation towards smart and wearable sensors. However, the preparation and functionalization of the sensing material remain challenging for real-time application. In this regard, herein, a novel free-standing nanosheet strategy involving sputtering technique is proposed for toxic ammonia (NH 3 ) sensing application. Radio frequency (RF) sputtered vanadium pentoxide (V 2 O 5 ) film was used as the sensing layer on the biocompatible poly- l -lactic acid (PLLA) substrate of ∼130 nm. The deposited V 2 O 5 film was carefully evaluated for its control in thickness, morphology, and topographical characteristics in addition to its elemental studies. X-ray photoelectron spectroscopy (XPS) confirmed the highly stable V +5 oxidation state with the binding energy of 516.8 and 524.2, corresponding to V2p 3/2 and V2p 1/2 peaks. From the chemiresistive sensing analysis, V 2 O 5 film exhibited a sensor response (R a /R g ) of 1.2 towards 5 ppm NH 3 at room temperature. The sensing mechanism of n-type V 2 O 5 towards reducing NH 3 has been schematically explained. It is worth emphasizing that this work will pave the way for exploring novel yet facile preparation strategies for flexible sensing devices. We believe that the 2D freestanding nanosheets will provide remarkable advancements in flexible/wearable devices owing to their biocompatibility, conformability, flexibility, and light feel characteristics.

Self-growing graphite felt/vanadium pentoxide/polyindole ternary composite as binder-free electrode for supercapacitor with 1.8 V operating potential window and excellent electrochemical performance

Vanadium pentoxide and conducting polymers have promising applications in the field of electrical energy storage devices and combine flexible substance to form binder-free ternary electrodes, which would pave a new way for designing supercapacitors. Herein, graphite felt (GF)@V2O5 nanosheets is synthesized by hydrothermal and calcinating treatment, on the surface of which polyindole (PIn) nanospheres are anchored orderly using electrochemical deposition to obtain GF@V2O5@PIn ternary electrode material. The pseudocapacitive properties of both V2O5 nanosheets and PIn nanospheres are fully demonstrated through the synergistic effect of them, enabling ternary composite GVP-3 to exhibit superior electrochemical properties than two binary materials. The area capacitance of GVP-3 reaches 2254 mF/cm2, which is significantly higher than that of GF@V2O5 with 1431 mF/cm2 and GF@PIn with 647 mF/cm2. The flexible quasi-solid-state asymmetric supercapacitor (FASC) can be operated at the potential window of 1.8 V with a significant energy density of 1.423 mWh/cm3 (64.404Wh/kg) The excellent electrical capacitance and prominent energy density of our device endow it with an overall improvement of electrical performance from 25% to 30%, which is compared to present researches. Two devices connected in series are able to make a 3.5 V LED bump light up normally for 2 min, illustrating desirable practicality.

V2O5 nano sheets assembled on nitrogen doped multiwalled carbon nanotubes/carboxy methyl cellulose composite for two-electrode configuration of supercapacitor applications

Recently, the various 2D two-dimensional structural materials were synthesized and fabrication of electrodes for widely used in electrochemical capacitors, catalysis, electronics and energy renovation via hydrothermal reaction process. These materials provide the greater surface and ultrathin sheets morphology and enhances the asymmetric supercapacitor applications. V2O5@N-MWCNT and V2O5@N-MWCNT/CMC composite synthesized via hydrothermal process exhibited the sheet like morphological and larger surface properties for improved the supercapacitor applications. The electrochemical properties of the composite's electrodes were explored by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy studies. The composite materials were demonstrated a specific capacitance 138F g−1 at 1A g−1 applied current density, which is much superior than that of pristine V2O5 materials. Furthermore, the composite electrodes show the excellent cyclic stability up to 5000 cycles with 98.6% retention in presence of 1 M H2SO4 electrolyte. The enhancement of electrochemical behaviour due to the increasing surface area and morphological properties of synthesized composite.

Synthesis and electrochemical performance of V2O5 nanosheets for supercapacitor

Electrode materials are the key to the electrochemical performance of supercapacitors. This study reports the electrochemical properties of V2O5 supercapacitors. V2O5 nanosheets with different morphologies were prepared by controlling the solvent under a facile hydrothermal method. The phase and the morphology of the samples were characterized by x-ray diffraction and scanning electron microscopy. The electrochemical properties of V2O5 nanosheets with different morphologies were studied by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The charge transfers resistance decreases from 3.2 Ω of V2O5 particles to 2.0 Ω of V2O5 nanosheets. V2O5 nanosheets exhibit higher specific capacity (375 F g−1) than V2O5 particles (318 F g−1) in K2SO4 solution. The cycling capacity retention keeps 96.8% for 1000 cycles at 0.5 A g−1 in K2SO4 solution, indicating better cycling stability.

A V2O5-based freestanding anode with high rate and superior cycle life for potassium storage

Potassium-ion batteries (PIBs) are emerging as a new hotspot of research in energy storage technology due to the resource abundance and low cost of potassium. However, the large size of K+ results in a significant challenge for developing high-rate and long-life anode materials for PIBs. Herein, we proposed a freestanding anode material of carbon-coated V2O5 nanosheets arranged vertically on carbon fibers (C@V2O5@CNFs) for potassium storage. The CNFs as the skeleton regulates the vertical alignment of V2O5 nanosheets, thereby avoiding the self-agglomeration effectively. Moreover, the carbon coating layer not only stabilizes the structural integrity and further enhances the electrical conductivity of hybrid electrodes. Consequently, the C@V2O5@CNFs shows excellent reversible capacity and long-term cycle stability.

Flexible electrode material of V2O5 carbon fiber cloth for enhanced zinc ion storage performance in flexible zinc-ion battery

As a new generation of electrode material, flexible electrode material can effectively broaden the application area and scope of energy storage devices. In this paper, a new vanadium pentoxide carbon fiber cloth (V2O5-CFC) is successful synthesized by means of electrospinning and high-temperature calcination. As a cathode material for aqueous zinc-ion batteries, V2O5-CFC possesses significantly increased specific capacity (132 mA h g−1 at 1 A g−1) and good cycling ability (154 mA h g−1 at 0.5 A g−1 after 1000 cycles). The volume effect in the charge/discharge process can be alleviated by using a composite fiber structure to avoid agglomeration of V2O5 nanosheets. Most important, V2O5-CFC displays the flexible property and demonstrates its potential applications as a high-energy density and flexible energy storage device with good reversibility. Therefore, the design and synthesis strategy of flexible nanofibers film is prospective for applications in next-generation flexible aqueous zinc-ion batteries.

Organic Macromolecule regulated the structure of vanadium oxide with high capacity and stability for aqueous Zinc-ion batteries

The aqueous zinc-ion rechargeable batteries (AZIBs) have become a promising alternative for large-scale energy storage applications and triggered a great deal of scientific research due to low cost, high security, and eco-efficiency. Here, we report the successful synthesis of phytic acid coated/inserted V2O5 nano-composites (PHVO) by one-step hydrothermal method. On one hand, the surface of V2O5 nanosheets is uniformly coated by phytic acid to form an ultrathin layer, serving as a stabilizer to greatly enhance the structural stability by restraining the exfoliation of active materials during the cycling process. On the other hand, the phytic acid plays as the intercalary spacer to expand the V2O5 interlayer distance to 13.5 Å, which is beneficial to the diffusion kinetics of Zn2+ by offering expedited channels. With the abovementioned advantages, the overall electrochemical performance of PHVO has been significantly improved. It showed an excellent specific capacity of 406 mAh g−1 at 0.1 A g−1, and the capacity retention rate was 97.3% after 6000 cycles at 5 A g−1. This work paves the way to the design and fabrication of stable cathodes for AZIBs with excellent electrochemical performance.

Facile preparation of functionalized and oxygen-deficient V2O5 nanosheets electrode as a versatile platform for biomimetic- and photoelectro-catalysis

Facile preparation of functionalized and oxygen-deficient V 2 O 5 nanosheets modified electrode with enhanced biomimetic- and photoelectro-catalytic activity • One-step preparation of functionalized V 2 O 5 nanosheets electrode was demonstrated. • Roles of formamide in functionalizing V 2 O 5 nanosheets electrode was uncovered. • The obtained electrode (FTO|exf-V 2 O 5 ) can reduce Ag ions to Ag nanoparticles. • FTO|exf-V 2 O 5 shows remarkably high H 2 O 2 affinity and biomimetic activity. • Photoelectrocatalytic activity of FTO|exf-V 2 O 5 to methanol oxidation was explored. In this study, we present a facile and scalable preparation of formamide-functionalized and oxygen-deficient V 2 O 5 nanosheets (thickness: 30 ∼ 40 nm) modified electrode (FTO| exf -V 2 O 5 ) with promising peroxidase-like and photoelectrocatalytic activity. FTO| exf -V 2 O 5 was prepared by the direct top-down exfoliation of the V 2 O 5 sub-micron plates (thickness: 300 ∼ 550 nm) modified electrode (FTO| micro -V 2 O 5 ) in the presence of formamide as the exfoliation agent at mild conditions. Formamide molecules were found to adsorb on FTO| exf -V 2 O 5 and serve as the active sites for the reduction of noble metal, which not only enables the application of FTO| exf -V 2 O 5 for the recovery of noble metals but also allows further functionalization and electrocatalytic oxidation of H 2 O 2 . As compared with FTO| micro -V 2 O 5 , FTO| exf -V 2 O 5 had significantly higher oxygen vacancy (V O ) content and exhibited remarkably enhanced peroxidase activity with an ultra-low Michaelis-Menten constant of 68.24 μM and a high catalytic constant (or maximal turnover frequency) of 0.28 s −1 . Finally, FTO| exf -V 2 O 5 with lower dimension and higher V O content showed improved kinetics of charge-transport and interfacial charge-transfer, resulting in the enhanced activity towards photoelectrocatalytic oxidation of water and methanol. This work opens a new avenue for the preparation of exfoliated 2-D material based platform for biomimetic catalysis and energy conversion.

Coherent V4+-rich V2O5/carbon aerogel nanocomposites for high performance supercapacitors

V4+-rich V2O5/carbon aerogel (V4+-V2O5/CA) composites were synthesized as electrode materials for supercapacitors via in-situ hydrolysis-condensation processing. Carbon aerogel (CA) promotes the deposition of amorphous vanadium oxide and catalyzes the crystallization of V4+-rich V2O5 nanosheets at much reduced temperature. With a uniform distribution of V2O5 nanosheets in CA, the special structure provides a large specific area and reactive sites. CA also synergistically improves the electrical conductivity and structural integrity. In addition, rich V4+ would enhance the intrinsic electrical conductivity of V2O5, promote ion diffusion and catalyze the electrochemical reactions. Consequently, V4+−V2O5/CA exhibits much enhanced specific capacitance (405 F g−1 at 0.5 A g−1), high energy density (56 W h kg−1 with a power density of 250 W kg−1) and long cycle life (96% capacitance retention after 40,000 cycles).

Polyaniline intercalated vanadium pentoxide nanosheets for the improvement of lubricity of base oil

Vanadium pentoxide (V2O5) nanosheets were prepared and tested as an additive to improve the wear/friction-reducing and load-carrying properties of the base lube, paraffin oil. For further advancement of these properties, in situ intercalation of polyaniline (PANI) was achieved hydrothermally using the starting materials as V2O5 powder and aniline. During the process, V2O5 powder was exfoliated into nanosheets, and aniline was oxidatively polymerized under acidic conditions producing polyaniline, which intercalated between the nanosheets to yield the composite PANI-V2O5.nH2O (PVO). Separately synthesized PANI, exfoliated V2O5 nanosheets, and the in situ synthesized composite were characterized by p-XRD, HR-SEM, TEM, FTIR, and XPS. Intercalated PANI prevented restacking of nanosheets and reduced their agglomerating tendencies. A significant increase of interplanar spacing corresponding to the (001) plane of V2O5 in the nanocomposite confirms considerable interaction between the nanosheets and PANI. Although there is no chemical interaction, the non-covalent interactions like hydrogen bonding between the organic and the inorganic components through NH(PANI)...... O-V(V2O5) and van der Waals forces hold the structure firmly. Tribological tests performed on a four-ball tester following ASTM D4172 and ASTM D5183 standards in paraffin oil revealed significant enhancement in friction/wear-reducing and load-carrying properties of the composite compared to V2O5 nanosheets and PANI. The advanced activity of the nanocomposite validates synergy between PANI and V2O5 nanosheets. The morphological studies of the worn surface by SEM and AFM studies endorsed the observed results. The EDX and XPS studies of the tribofilm confirmed the elemental composition and chemical states of all the elements, respectively. A possible mechanism of lubrication has been presented.

V-MOF@graphene derived two-dimensional hierarchical V2O5@graphene as high-performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are attracting growing attention in the field of grid-scale energy storage systems due to their reliable safety and low cost. However, it is still hindered by the limited choices of suitable cathode materials with high performance for aqueous ZIBs. Herein, we developed a V-MOF@graphene derived two-dimensional hierarchical V2O5@graphene for the first time, where the porous V2O5 nanosheets are homogeneously attached to the 2D graphene substrate. Benefiting from the unique 2D composite structure with excellent electronic and ionic conductivity, adequate active sites, as well as the synergistic effect between the ultrathin V2O5 nanosheets and graphene, the V2O5@graphene here exhibits outstanding electrochemical performance in aqueous ZIBs. Particularly, it delivered an ultrahigh reversible capacity of 378 mAh/g at a current density of 2 A/g. What is more, a high specific capacity of 305 mAh/g after 100 cycles at 0.1 A/g and 200 mAh/g after 1,000 cycles at 1 A/g can be achieved. These ideal results suggest that the V2O5@graphene cathode hold great promise for high-performance aqueous zinc-ion batteries.

Enhancing lithium/sodium-ion storage behaviors in a V2O5 nanosheet by freeze-drying

A porous V2O5 nanosheet is synthesized via freeze-drying followed by a heat-treatment process.

Electronic and Vibrational Decoupling in Chemically Exfoliated Bilayer Thin Two-Dimensional V2O5.

The synthesis of high-quality two-dimensional (2D) transition metal oxides is challenging compared to 2D transition metal dichalcogenides as a result of the exotic surface changes that can appear during formation. Herein, we report the synthesis of bilayer 2D V2O5 nanosheets with a thickness of ∼1 nm using the chemical exfoliation method and a comprehensive study on the vibrational and optical properties of bilayer 2D V2O5. We report, for the first time, a thickness-dependent blue shift of 1.33 eV in the optical bandgap, which signifies the emergence of electronic decoupling in bilayer 2D V2O5. In addition, a thickness-dependent vibrational decoupling of phonon modes observed via Raman spectroscopy fingerprinting was verified by computing the lattice vibrational modes using the density functional perturbation theory. We demonstrate that the manifestation of the electronic and vibrational decoupling can be used as a benchmark to confirm the successful formation of bilayer 2D V2O5 from its bulk counterpart.

Cascading V2O3/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries (LIBs), aqueous Zn-ion batteries (ZIBs) have been getting a lot of attention because of their cost-effectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivalence. However, vanadium oxide cathodes still suffer from unsatisfactory capacity, poor stability, and low electrical conductivity. In this work, cascading V2O3/nitrogen doped carbon (V2O3/NC) hybrid nanosheets are prepared for high-performance aqueous ZIBs by pyrolyzing pentyl viologen dibromide (PV) intercalated V2O5 nanosheets. The unique structure features of V2O3/NC nanosheets, including thin sheet-like morphology, small crystalline V2O3 nanoparticles, and conductive NC layers, endow V2O3/NC with superior performance compared to most of the reported vanadium oxide cathode materials for aqueous ZIBs. The V2O3/NC cathode exhibits the discharge capacity of 405 mAh/g at 0.5 A/g, excellent rate capability (159 mAh/g at 20 A/g), and outstanding cycling stability with 90% capacity retention over 4000 cycles at 20 A/g.

Oxygen-defective V2O5 nanosheets boosting 3D diffusion and reversible storage of zinc ion for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have received considerable attention for reliable and low-cost energy storage. However, it remains a great challenge to develop cathode materials with high capacity and adequate cycle life due to the high polarization of bivalent Zn2+. Defect engineering has been demonstrated to enhance the electrochemical reaction sites but most defects are restricted to the surface of materials. We overcome this issue by incorporation of defect engineering and nanoengineering. Oxygen-defective V2O5 nanosheet arrays anchored on carbon cloth are employed as the cathode of ZIBs, which delivering comparable reversible capacity (322.9 and 256.6 at 1 and 5 A g−1) and stable cyclability (220 mAh g−1 after 500 cycles at 10 A g−1). Further DFT calculations validate that Zn2+ diffusion in oxygen-defective V2O5 is allowed along c axis, not only restricted along ab plane of V2O5, thus realizing a 3D Zn2+ diffusion with fast electrochemical kinetics and large capacitive storage. Moreover, the Zn2+ adsorption energies at defective sites of V2O5 was close to thermoneutral value, contributing reversible Zn2+ adsorption/desorption for ultra-stable Zn2+ storage performance. This synergistic strategy of defect engineering and nanoengineering reveal a promising potential for advanced materials of aqueous Zn-ion batteries and flexible storage applications.

Growth of large-area petal-like V2O5 thin nanosheets for superior lithium storage

There is a need for simple and rapid methods of controllably fabricating large-area V2O5 thin nanosheets for applications in high-energy Li-ion batteries (LIBs). Here, we report a novel growth-induced synthesis of two-dimensional (2D) petal-like V2O5 nanosheets with a thickness of approximately 15 nm and lateral size exceeding 5 µm. The mechanism of formation of the nanosheets is systematically investigated by studying the effects of reagent concentrations on the nanosheet morphology. The resultant V2O5 nanosheets were effective cathode materials for LIBs, giving high reversible capacities of 291.7 and 101 mAh g−1 at current densities of 0.1 and 3.0 A g−1, respectively, in the voltage window of 2.0–4.0 V. Furthermore, the cathode operated stably for 200 cycles at 1.5 A g−1, with a reversible capacity of 139.6 mAh g−1 at the 200th cycle, corresponding to a capacity fading of 0.03% per cycle. The enhanced lithium storage is attributed to the increased electrode/electrolyte contact area, the enhanced strain tolerability, and shortened charge transport path of the unique nanosheet structure. The influence of the electrochemical reaction kinetics on the performance is also discussed in detail. These findings will accelerate the development of V2O5 cathodes for next generation high-energy LIBs.