Functional Tailoring of Multi‐Dimensional Pure MXene Nanostructures for Significantly Accelerated Electromagnetic Wave Absorption

Abstract Transition metal carbide (Ti 3 C 2 T x MXene), with a large specific surface area and abundant surface functional groups, is a promising candidate in the family of electromagnetic wave (EMW) absorption. However, the high conductivity of MXene limits its EMW absorption ability, so it remains a challenge to obtain outstanding EMW attenuation ability in pure MXene. Herein, by integrating HF etching, KOH shearing, and high‐temperature molten salt strategies, layered MXene (L‐MXene), network‐like MXene nanoribbons (N‐MXene NRs), porous MXene monolayer (P‐MXene ML), and porous MXene layer (P‐MXene L) are rationally constructed with favorable microstructures and surface states for EMW absorption. HF, KOH, and KCl/LiCl are used to functionalize MXene to tune its microstructure and surface state (F − , OH − , and Cl − terminals), thereby improving the EMW absorption capacity of MXene‐based nanostructures. Impressively, with the unique structure, proper electrical conductivity, large specific surface area, and abundant porous defects, MXene‐based nanostructures achieve good impedance matching, dipole polarization, and conduction loss, thus inheriting excellent EMW absorption performance. Consequently, L‐MXene, N‐MXene NRs, P‐MXene ML, and P‐MXene L enable a reflection loss ( R L ) value of −43.14, −63.01, −60.45, and −56.50 dB with a matching thickness of 0.95, 1.51, 3.83, and 4.65 mm, respectively.