Abstract
MXenes and MXene-based composite materials have potential applications in a wide range of areas due to their unique physical and chemical characteristics. At present, it is still a major challenge to develop a simple, safe, and efficient route to prepare MXenes without using fluorinated etchants. Herein, we design a facile method to prepare Ti(3)C(2)T(x) MXene sheets by selectively etching Ti(3)AlC(2) powders in an aqueous diluted H(2)SO(4) solution with H(2)O(2) as an oxidant. In a system of H(2)SO(4) and H(2)O(2), an aqueous H(2)SO(4) solution with a concentration of 6 mol/L is a strongly acidic medium with no volatility, and 30% H(2)O(2) acts as a strong green oxidizer without harmful by-products. The experimental process is safe and convenient to conduct in a beaker under a water bath of 40°C. The etching process can be completed in 1 h under the air atmosphere conditions. The experimental results confirmed that the etched Ti(3)AlC(2) powders can be successfully separated into Ti(3)C(2)T(x) nanosheets under ultrasound treatment without using any intercalation agent. The relevant etching mechanism is may be attributed to the synergy effect of H(2)SO(4) and H(2)O(2), which triggers sequential selective etching of Al layers from the Ti(3)AlC(2) phase. It may provide a new green way to prepare MXene-based materials without using toxic HF or HF-containing etchants.