Regenerating MXene by a Facile Chemical Treatment Method

Abstract

A popular substance in the MXene family, titanium carbide (Ti 3 C 2 T x ), has received substantial attention mainly due to its high metallic conductivity, easy solution processability, and environment friendliness. However, the poor oxygen resistance nature of MXene has prevented its practical applications from being realized. Despite significant attempts to improve the oxidative stability of MXenes, a comprehensive understanding of the oxidation mechanism is still elusive, thus leaving an optimal strategy for recycling oxidized MXene in question. Here, by developing a facile hydrofluoric acid (HF) posttreatment, we have unraveled the regeneration kinetics of the oxidized Ti 3 C 2 T x . A systematic and extensive investigation using a combination of Raman spectroscopy, scanning electron microscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy revealed that HF post-treatment is critical for restoring the structure/morphology and surface composition of MXene nanosheets. These are ascribed to the oxidizing agent removal kinetics, while the generation of amorphous carbon and Ti(III) in fluorinated derivatives provides efficient electrical conductivity. Our findings suggested that HF post-treatment is sufficient to evade and reduce the degradation process while maintaining the conductivity for a longer time, which will not only be economically advantageous but also a step forward for the rational design of Ti 3 C 2 T x -based devices and functional coatings.

Near‐Atomic‐Scale Perspective on the Oxidation of Ti3C2Tx MXenes: Insights from Atom Probe Tomography

“…[19,20] For MXenes and their surface terminations, most studies to date have relied heavily on X-ray (photoelectron) spectroscopy and electron microscopy techniques for compositional measurements. [21][22][23][24][25] However, these techniques have certain limitations, [26] particularly in their ability to accurately detect light elements surrounded by heavy transition metals. For instance, although the detection limit of X-ray photoelectron spectroscopy is typically given as 0.1 to 1 at%, it can exceed 10 at% for light elements surrounded by heavy elements.…”