Stoichiometry-Programmed MXenes via Precursor Engineering for High-Performance EMI Shielding and Energy Storage.

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• MXene material performance, crucial for applications like electromagnetic interference (EMI) shielding and energy storage, is highly dependent on its physical architecture.
• Current synthesis methods offer limited control over deterministic architectural programming, hindering the optimization of MXene properties for specific applications.
• The relationship between precursor stoichiometry and the resulting MXene morphology remains largely unexplored.

Purpose of the Study:

• To investigate the impact of precise carbon stoichiometry control in Ti3AlCxO2-x MAX phases on the emergent MXene architecture.
• To establish a direct link between precursor chemistry and the final MXene structure and its functional properties.
• To demonstrate a synthesis-stage approach for designing MXene architectures tailored for specific applications.

Main Methods:

• Controlled synthesis of Ti3AlCxO2-x MAX phases with varying carbon stoichiometry (x = 1.94 and x = 1.71).
• Characterization of MAX phase lattice strain and MXene morphology using advanced techniques.
• Evaluation of MXene properties for electromagnetic interference (EMI) shielding and energy storage applications.

Main Results:

• Carbon-rich precursors (x = 1.94) produced highly crystalline, strain-relieved nanosheets with excellent metallic conductivity, achieving record EMI shielding (≥ 2.0 × 10^6 dB cm^2 g^-1 at 8.2 GHz) and bending stability.
• Carbon-deficient precursors (x = 1.71) led to lattice compression and oxygen substitution, resulting in nanoscrolls with superior ion accessibility for energy storage (657 F g^-1 at 2 mV s^-1 with 99.4% retention).
• Demonstrated deterministic control over MXene architecture by programming precursor stoichiometry.

Conclusions:

• Precise control over carbon stoichiometry in MAX phase precursors is a viable strategy to deterministically tune MXene architecture and properties.
• This approach enables the rational design of MXene materials for distinct applications, such as high-performance EMI shielding or advanced energy storage.
• The stoichiometry-programmed synthesis offers a pathway for developing next-generation electronic and energy storage devices using established MAX/MXene workflows.