Integrating self-powering and electromagnetic interference shielding into MXene-based fire-sensing films via hetero-interface engineering

MXene-based fire-sensing films are expected to integrate self-powered fire monitoring and excellent electromagnetic interference (EMI) shielding for electronic devices. However, quantum interlocking of thermoelectric and charge transport in high-dimensional degenerate MXene limits their synergistic enhancement. Here, a multifunction-integration strategy was proposed by regulating competition of Seebeck coefficient and conductivity on carrier concentration, based on hetero-interface engineering of hierarchical “brick/mortar” structure. This structure with gradient impedance matching was designed by sandwiching an MXene inner layer between two hybrid-nanoparticle outer layers, which are assembled by tunicate cellulose nanocrystals (tCNCs) and ammonium polyphosphate (APP) inserting into MXene nanosheets (MAC) through hydrogen bonds and electrostatic interactions. The obtained 1.2 ​mm self-powered composite film (MAC@MX40) generates a maximum Seebeck voltage of 6.2 ​mV to trigger an alarm signal lasting over 113.28 ​s within 2.74 ​s upon exposure to flame without external power. An excellent absorption-domainance EMI shielding effectiveness of 64.3 ​dB within the frequency range of 8.2–12.4 ​GHz (X-band) is achieved, consistent with the result of finite element simulation. The good Joule heating capacity is confirmed by a tunable saturation temperature of 20–114 ​°C within 100 ​s under voltages 1–5 ​V. The tensile strength of 80.9 ​MPa and elongation at break of 5.9 ​% are also achieved, respectively increasing 99.9 ​% and 4.1 ​% compared to the MXene counterpart. This multifunction strategy simultaneously enables MXene-based films to be self-powered fire-sensing and EMI shielding for better life and property protection. • Promoted Seebeck effect for self-powered fire-sensing of MXene-based film. • Integrated multifunction via synergistic micro/macro hierarchical structural design. • 2.74 ​s sensitive response and 113.28 ​s alarm duration in self-powered mode. • 64.3 ​dB EMI SE and prediction model of finite element simulation.