Selected-control hydrothermal synthesis and formation mechanism of 1D ammonium vanadate

N and O multi-coordinated vanadium single atom with enhanced oxygen reduction activity

Recently, atomically dispersed transition-metal single atom in nitrogen-doped carbon matrix as electrocatalysts has aroused general interest. However, there is no report about vanadium single atom for ORR in the literature. According to d-band center theory for transition-metals, the performance of catalysts is regulated by the electronic structure of the catalytic center which determines the intermediate adsorption kinetics. Indeed, the valence of vanadium is variable, its electron structure could be modulated by an appropriate coordination structure. Here, a novel method is developed to prepare the N and O co-coordinated vanadium single atom (V-N₁O₄) embedded in the carbon matrix. The catalyst displays a half-wave potential of 865 mV in base solution which surpasses 20% Pt/C, and also shows a high power density of 180 mW/cm² in Zn-air batteries. DFT calculations reveal that the N and O coordination configuration could regulate the electron structure and geometry of vanadium to boost the electrocatalytic activity.

Superior light absorbing CdS/vanadium sulphide nanowalls@TiO2 nanorod ternary heterojunction photoanodes for solar water splitting

Vanadium sulphide is an emerging infrared active photocatalyst that has not been utilized to its maximum potential.

A High-Capacity Ammonium Vanadate Cathode for Zinc-Ion Battery

Given the advantages of being abundant in resources, environmental benign and highly safe, rechargeable zinc-ion batteries (ZIBs) enter the global spotlight for their potential utilization in large-scale energy storage. Despite their preliminary success, zinc-ion storage that is able to deliver capacity > 400 mAh g-1 remains a great challenge. Here, we demonstrate the viability of NH4V4O10 (NVO) as high-capacity cathode that breaks through the bottleneck of ZIBs in limited capacity. The first-principles calculations reveal that layered NVO is a good host to provide fast Zn2+ ions diffusion channel along its [010] direction in the interlayer space. On the other hand, to further enhance Zn2+ ion intercalation kinetics and long-term cycling stability, a three-dimensional (3D) flower-like architecture that is self-assembled by NVO nanobelts (3D-NVO) is rationally designed and fabricated through a microwave-assisted hydrothermal method. As a result, such 3D-NVO cathode possesses high capacity (485 mAh g-1) and superior long-term cycling performance (3000 times) at 10 A g-1 (~ 50 s to full discharge/charge). Additionally, based on the excellent 3D-NVO cathode, a quasi-solid-state ZIB with capacity of 378 mAh g-1 is developed.

Tailoring the Size and Shape-New Path for Ammonium Metavanadate Synthesis

Ammonium metavanadate, NH₄VO₃, plays an important role in the preparation of vanadium oxides and other ammonium compounds, such as NH₄V₃O₈, (NH₄)₂V₃O₈, and NH₄V₄O₁₀, which were found to possess interesting electrochemical properties. In this work, a new route for the synthesis of NH₄VO₃ is proposed by mixing an organic ammonium salt and V₂O₅ in a suitable solvent. The one-step procedure is carried out at room temperature. Additionally, the need for pH control and use of oxidants necessary in known methods is eliminated. The mechanism of the NH₄VO₃ formation is explained. It is presented that it is possible to tailor the morphology and size of the obtained NH₄VO₃ crystals, depending on the combination of reagents. Nano- and microcrystals of NH₄VO₃ are obtained and used as precursors in the hydrothermal synthesis of higher ammonium vanadates. It is proven that the size of the precursor particles can significantly affect the physical and chemical properties of the resulting products.

V2O5 nanobelt arrays with controllable morphologies for enhanced performance supercapacitors

Controllable preparation of V₂O₅ nanobelt arrays as binder-free supercapacitive electrode materials and their charge–discharge mechanism.

Structural transformation during Li/Na insertion and theoretical cyclic voltammetry of the δ-NH4V4O10 electrode: a first-principles study

A double layer δ-NH₄V₄O₁₀, due to its high energy storage capacity and excellent rate capability, is a very promising cathode material for Li-ion and Na-ion batteries for large-scale renewable energy storage in transportation and smart grids.

Three-Dimensional Porous Iron Vanadate Nanowire Arrays as a High-Performance Lithium-Ion Battery

Development of three-dimensional nanoarchitectures on current collectors has emerged as an effective strategy for enhancing rate capability and cycling stability of the electrodes. Herein, a new type of three-dimensional porous iron vanadate (Fe0.12V2O5) nanowire arrays on a Ti foil has been synthesized by a hydrothermal method. The as-prepared Fe0.12V2O5 nanowires are about 30 nm in diameter and several micrometers in length. The effect of reaction time on the resulting morphology is investigated and the mechanism for the nanowire formation is proposed. As an electrode material used in lithium-ion batteries, the unique configuration of the Fe0.12V2O5 nanowire arrays presents enhanced capacitance, satisfying rate capability and good cycling stability, as evaluated by cyclic voltammetry and galvanostatic discharge-charge cycling. It delivers a high discharge capacity of 293 mAh·g(-1) at 2.0-3.6 V or 382.2 mAh·g(-1) at 1.0-4.0 V after 50 cycles at 30 mA·g(-1).

Synthesis of novel ammonium vanadium bronze (NH4)0.6V2O5 and its application in Li-ion battery

A novel ammonium vanadium bronze (NH₄)_0.6V₂O₅ has been successfully synthesized via a simple hydrothermal treatment and its electrochemical performance is investigated.