Anomalous absorption of electromagnetic waves by 2D transition metal carbonitride Ti ₃ CNT <i> _x </i> (MXene)

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, Ti₃CNT <i>_x</i> MXene, with a moderate electrical conductivity, provides a higher shielding effectiveness compared with more conductive Ti₃C₂T <i>_x</i> or metal foils of the same thickness. This exceptional shielding performance of Ti₃CNT <i>_x</i> 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.