Delaminated V₂C MXene Nanostructures Prepared via LiF Salt Etching for Electrochemical Applications

Abstract

Vanadium carbide MXenes have demonstrated both one of the highest theoretical capacities for Li and Mg storage among all members of the MXene family and a high performance as cathodes for high-energy-density Zn-ion batteries (ZIBs). However, V2C research has been limited because of the instability of delaminated V2C (d-V2C) in water suspension. Herein, we propose improvements of the HF-free synthesis of V2C MXenes via selective etching of the V2AlC MAX phase by a HCl and LiF mixture. A combination of etching in the closed environment of the hydrothermal autoclave under continuous stirring and thermal isolation of a reaction vessel and improved washing techniques result in high-quality d-V2C MXene nanostructures. High crystallinity and chemical purity of the as-synthesized materials is confirmed by X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and aberration-corrected high-resolution transmission electron microscopy. A high concentration of Li cations in the etching mixture results in significantly improved stability of d-V2C in water suspension. In addition, cyclic voltammetry analysis is conducted to gauge the electrochemical characteristics of fabricated d-V2C MXenes. Electrochemical tests confirm that fabricated MXenes are highly promising as cathode materials for aqueous ZIBs. Moreover, a charge storage mechanism of V2C MXenes can be tuned through the implementation of different synthetic methods as well as electrochemical activation protocols.

Recent advances in MXenes: beyond Ti-only systems

“…The etching of the MAX phase is usually carried out using HF, a mixture of acid and uoride salt, molten salts, hydrothermal, electrochemical, and Lewis acid methods. 31,[67][68][69][70] Chemical vapor deposition (CVD), a bottom-up approach, was also used in synthesizing non-Ti MXenes. 71 The type of etchant used greatly inuences the surface chemistry and properties of the resultant MXene.…”

“…129 Recently, Firestein et al reported that electrochemically activated delaminated V 2 C MXene exhibited excellent performance as a cathode for aqueous zinc-ion batteries (ZIBs). 67 It was shown that the charge storage mechanism of delaminated V 2 C MXene could be tuned with different activation processes. As discussed in the previous section, the functional groups (–O, –F, and –OH) created on the surface of the multilayered MXene help in tuning the properties of MXenes.…”

Effects of polyacrylic acid molecular weights on V2C-MXene nanocoatings for obtaining ultralow friction and ultralow wear in an ambient working environment

“…28 In contrast to Ti 3 C 2 -MXene, V 2 C-MXene has more excellent storage capacity and hydrophobicity. [29][30][31] Hence, in this study, the tribological characteristics of the V 2 C-MXene nanocoatings modified by PAA with different molecular weights were explored by using a ball-on-plate tribometer paired with two types of counterpairs operating in a linear reciprocating mode under air conditions. The underlying lubrication mechanisms of V 2 C-MXene nanocoatings were revealed using a Raman spectrometer, three-dimensional white-light interferometry topography images, optical microscope, focused ion beam/ scanning electron microscope (FIB/SEM) and high-resolution transmission electron microscope/energy dispersive spectrometer (HRTEM/EDS).…”

ACS Applied Nano Materials Australia Forum

“…One of the works in the forum is dedicated to nanomaterials with applications in energy storage. Firestein et al from Queensland University of Technology developed a synthesis process for V 2 C MXenes that relied on relatively safe materials with potential applications in Zn-ion batteries …”

“…Firestein et al from Queensland University of Technology developed a synthesis process for V 2 C MXenes that relied on relatively safe materials with potential applications in Zn-ion batteries. 5 The implementations of nanomaterials as viable candidates for water purification, pollutant removal and for anti-bacterial applications are the foci of three studies in this collection. Deb et al from the University of Newcastle introduced magnetite nanoparticles loaded into halloysite nanotubes for arsenic removal from water.…”