Formation of Crystalline Na2V6O16·3H2O Ribbons into Belts and Rings

Effect of Cu doping on the photocatalytic activity of InVO4 for hazardous dye photodegradation under LED light and its mechanism

Cu doped InVO₄ (xCu-InVO₄ (x = 0.06-0.15 wt %) was synthesized by a facile one-pot hydrothermal method for the removal of methylene blue (MB) under LED light irradiation. The X-ray photoelectron spectroscopy (XPS) analysis indicated the coexistence of V⁵⁺ and V⁴⁺ species due to the O-deficient nature of the xCu-InVO₄. The synthesized photocatalysts displayed a morphology of spherical and square shaped particles (20-40 nm) and micro-sized rectangle rods with a length range of 100-200 μm. The xCu-InVO₄ exhibited superior adsorption and photodegradation efficiency compared to pristine InVO₄ and TiO₂ due to the presence of O₂ vacancies, V⁴⁺/V⁵⁺ species, and Cu dopant. The optimum reaction conditions were found to be 5 mg L^-1 (MB concentration), pH 6, and 100 mg of photocatalyst mass with a removal efficiency and mineralization degree of 100% and 96.67%, respectively. The main active species responsible for the degradation of MB were ^•OH radicals and h⁺. Reusability studies indicated that the 0.13Cu-InVO₄ was deactivated after a single cycle of photocatalytic reaction due to significant leaching of V⁴⁺ and Cu²⁺ species.

Freestanding Potassium Vanadate/Carbon Nanotube Films for Ultralong-Life Aqueous Zinc-Ion Batteries

Among various energy storage devices, aqueous zinc-ion batteries (ZIBs) have captured great attention due to their high safety and low cost. One of the most promising cathodes of aqueous ZIBs is layered vanadium-based compounds. However, they often suffer from the capacity decaying during cycling. Herein, we prepared KV₃O₈·0.75H₂O (KVO) and further incorporated it into a single-walled carbon nanotube (SWCNT) network, achieving freestanding KVO/SWCNT composite films. The KVO/SWCNT cathodes exhibit a Zn²⁺/H⁺ insertion/extraction mechanism, resulting in fast kinetics of ion transfer. In addition, the KVO/SWCNT composite films possess a segregated network structure, which offers the fast kinetics of electron transfer and guarantees an intimate contact between KVO and SWCNTs during cycling. As a result, the resultant batteries deliver a high capacity of 379 mAh g^-1, excellent rate capability, and an ultralong cycle life up to 10,000 cycles with a high capacity retention of 91%. In addition, owing to the high conductivity and flexibility of KVO/SWCNT films, flexible soft-packaged ZIBs based on KVO/SWCNT film cathodes were assembled and displayed stable electrochemical performance at different bending states.

Aqueous rechargeable zinc/sodium vanadate batteries with enhanced performance from simultaneous insertion of dual carriers

Rechargeable aqueous zinc-ion batteries are promising energy storage devices due to their high safety and low cost. However, they remain in their infancy because of the limited choice of positive electrodes with high capacity and satisfactory cycling performance. Furthermore, their energy storage mechanisms are not well established yet. Here we report a highly reversible zinc/sodium vanadate system, where sodium vanadate hydrate nanobelts serve as positive electrode and zinc sulfate aqueous solution with sodium sulfate additive is used as electrolyte. Different from conventional energy release/storage in zinc-ion batteries with only zinc-ion insertion/extraction, zinc/sodium vanadate hydrate batteries possess a simultaneous proton, and zinc-ion insertion/extraction process that is mainly responsible for their excellent performance, such as a high reversible capacity of 380 mAh g-1 and capacity retention of 82% over 1000 cycles. Moreover, the quasi-solid-state zinc/sodium vanadate hydrate battery is also a good candidate for flexible energy storage device.

Ultra-long Na2V6O16·xH2O nanowires: large-scale synthesis and application in binder-free flexible cathodes for lithium ion batteries

Large-scale synthesis and application of ultra-long Na₂V₆O₁₆·xH₂O nanowires as binder-free flexible cathodes for high performance LIBs are demonstrated.

Rational design of one-dimensional vanadium(v) oxide nanocrystals: an insight into the physico-chemical parameters controlling the crystal structure, morphology and size of particles

This highlight deals with the recent advances on the synthesis in aqueous solution of one-dimensional vanadium(v) oxide nanocrystals.

Controllable synthesis and morphology evolution from two-dimensions to one-dimension of layered K2V6O16·nH2O

In a hydrothermal process, layered K₂V₆O₁₆·2.7H₂O platelike crystals are split into layered K₂V₆O₁₆·1.5H₂O fiberlike crystals.