Low temperature solution synthesis of reduced two dimensional Ti₃C₂ MXenes with paramagnetic behaviour

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• MXenes, a class of two-dimensional (2D) early transition metal carbides and nitrides, represent a significant advancement in 2D materials.
• Understanding the fundamental properties of MXenes, including their magnetic behavior, is crucial for unlocking their technological potential.

Purpose of the Study:

• To develop a facile, low-temperature solution chemical synthesis method for reducing multilayered (ML) Ti3C2Tx MXenes.
• To investigate the magnetic properties of the synthesized Ti3C2Tx MXenes and determine the origin of any observed magnetism.

Main Methods:

• Solution chemical synthesis involving immersion of Ti3C2Tx MLs in Li-ethylenediamine (Li-EDA) at temperatures ranging from room temperature to 120 °C.
• Characterization using X-ray photoelectron spectroscopy, electron spin resonance, and magnetization measurements.
• Analysis of magnetic susceptibility (χ) as a function of temperature (T).

Main Results:

• The reduction process created Ti3+ ions and oxygen vacancies within the 2D Ti3C2Tx layers.
• Above approximately 10 K, the magnetic susceptibility was temperature-independent, indicating Pauli paramagnetism.
• The loss of magnetic signal upon intercalation and a Curie-like increase at low temperatures (<10 K) confirmed magnetism associated with the 2D flakes, suggesting proximity to a metal-insulator transition.

Conclusions:

• This study presents the first evidence of magnetism in any MXene material.
• The facile synthesis method yields reduced Ti3C2Tx MXenes with intrinsic magnetic properties.
• The findings open new avenues for exploring MXenes in spintronics and other magnetic applications.