Materials with good flexibility and high conductivity that can provide electromagnetic interference (EMI) shielding with minimal thickness are highly desirable, especially if they can be easily processed into films. Two-dimensional metal carbides and nitrides, known as MXenes, combine metallic conductivity and hydrophilic surfaces. Here, we demonstrate the potential of several MXenes and their polymer composites for EMI shielding. A 45-micrometer-thick Ti3C2Tx film exhibited EMI shielding effectiveness of 92 decibels (>50 decibels for a 2.5-micrometer film), which is the highest among synthetic materials of comparable thickness produced to date. This performance originates from the excellent electrical conductivity of Ti3C2Tx films (4600 Siemens per centimeter) and multiple internal reflections from Ti3C2Tx flakes in free-standing films. The mechanical flexibility and easy coating capability offered by MXenes and their composites enable them to shield surfaces of any shape while providing high EMI shielding efficiency.
Lightweight, ultrathin, and flexible
electromagnetic interference (EMI) shielding
materials are needed to protect electronic
circuits and portable telecommunication devices
and to eliminate cross-talk between devices and
device components. Here, we show that a
two-dimensional (2D) transition metal
carbonitride,
Ti3CNTx
MXene, with a moderate electrical conductivity,
provides a higher shielding effectiveness compared
with more conductive
Ti3C2Tx
or metal foils of the same thickness. This
exceptional shielding performance of
Ti3CNTx
was achieved by thermal annealing and is
attributed to an anomalously high absorption of
electromagnetic waves in its layered,
metamaterial-like structure. These results provide
guidance for designing advanced EMI shielding
materials but also highlight the need for
exploring fundamental mechanisms behind
interaction of electromagnetic waves with 2D
materials.
Terahertz (THz) shielding becomes increasingly important with the growing development of THz electronics and devices. Primarily materials based on carbon nanostructures or polymer–carbon nanocomposites have been explored for this application. Herein, significantly enhanced THz shielding efficiencies for 2D titanium carbide (Ti3C2 MXene) thin films with nanoscale THz metamaterials are presented. Nanoscale slot antenna arrays with strong resonances at certain frequencies enhance THz electromagnetic waves up to three orders of magnitude in transmission, which in turn enormously increases the shielding performance in combination with MXene films. Drop‐casting of a colloidal solution of MXene (a few micrograms of dry material) can produce an ultrathin film (several tens of nanometers in thickness) on a slot antenna array. Consequently, THz waves strongly localized in the near‐field regime by the slot antenna undergo enhanced absorption through the film with a magnified effective refractive index. Finally, the combination of an ultrathin MXene film and a nano‐metamaterial shows excellent shielding performance in the THz range.
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