MXenes for multispectral electromagnetic shielding

Electromagnetic interference (EMI) between unwanted electromagnetic (EM) waves and electronic circuits can lead to device malfunctions. The advancement of electronic, telecommunication and medical devices operating across a broad spectrum of EM waves (from ultralow kilohertz to high terahertz frequency) necessitates effective EMI shielding materials. MXenes — two-dimensional transition metal carbides, nitrides and carbonitrides — have emerged as EMI shielding materials that offer excellent metallic conductivity, large surface area, abundant surface terminations and facile solution processability. In composites with dielectric polymers, conducting carbons, magnetic particles and iontronic heterosystems, MXenes provide excellent multispectral EMI shielding against radiofrequency, gigahertz and terahertz or infrared-frequency waves at minimal thicknesses and in various structural forms. This Review delves into both theoretical and experimental aspects of the EMI shielding mechanisms of MXenes, showcasing their interaction with EM waves ranging from ultralow gigahertz to high terahertz frequency. The nanometre-thin pristine MXene films exhibit exceptionally low infrared emissivity, crucial for selective thermal management, infrared camouflage, stealth and anti-counterfeiting. MXene composites with polymers and magnetic inclusions not only enhance mechanical properties but also tune EMI shielding mechanisms. The Review also addresses challenges in developing MXene-based EMI shielding materials, offering insights into strategies and opportunities for their practical applications in electronics. Two-dimensional MXenes have emerged as state-of-the-art functional electromagnetic interference shielding materials in multispectral electromagnetic bands. Highly conductive and ultrathin films of MXenes can efficiently block electromagnetic waves from radiofrequency and gigahertz-range microwaves to terahertz or infrared-frequency waves.