High-performance electromagnetic interference shielding and thermoelectric conversion derived from multifunctional Bi2Te2.7Se0.3/MXene composites

High-performance electromagnetic interference (EMI) materials with remarkable thermoelectric conversion/self-powered capabilities seem to be predictably imperative to eliminate electromagnetic wave pollution and reduce local overheating of devices to ensure the reliable operation of electronic instruments and wearable electronic devices. Herein, multifunctional Bi2Te2.7Se0.3/Ti3C2Tx (BTS/MXene) composites are fabricated by mixing BTS and MXene dispersion followed by vacuum-assisted filtration and hot pressing, which exhibit highest EMI shielding efficiency (EMI SE) of 94.33 dB and average EMI SE of 83.4 dB over the whole X band (BTS/MX-30, containing 30 wt% MXene). Meanwhile, the BTS/MXene composites also demonstrate impressive thermoelectric (TE) conversion capabilities, achieving a peak dimensionless figure of merit (ZT) of 1.2 from 313 to 498 K for BTS/MX-1.5 (involving 1.5 wt% MXene). The excellent electromagnetic wave shielding performances originate from the reflection caused by the impedance mismatch, the multiple scattering at the BTS/MXene interface, the polarization at the terminal of MXene and BTS, etc. On the other hand, the excellent thermoelectric performance of BTS/MXene comes from the high conductivity of MXene and the blocking of low-energy carriers and the scattering of phonons at the interface. Hence, multifunctional BTS/MXene composites display broad prospects for simultaneous implementation of EMI shielding and thermoelectric conversion/self-powered applications in miniature and wearable electronic instruments.