MXene/nanocellulose/carbon sphere composite films with a multistage “egg-box” structure for electromagnetic-interference shielding and pressure sensors†

Abstract

With advances in smart wearable electronics, there is a substantial demand for flexible electronic skins with electromagnetic interference (EMI) shielding. Multifunctional materials that can monitor physiological signals and protect the human body from the harm of electromagnetic radiation are important. Herein, we fabricated MXene/nanocellulose/carbon sphere composite films (ACMF) like an “egg-box” by a densification strategy and an internal multilevel hierarchical architectural design. First, silver nanoparticles (AgNPs) were anchored onto cellulose nanocrystals microspheres through hydrothermal carbonization (the “egg”) while long-aspect-ratio flexible cellulose nanofibers and highly conductive Ti₃C₂T_x MXene layers functioned as the “box”. This unique internal multilayered structure mitigated the agglomeration of MXene, and expanded the interlayer spacing. ACMF exhibited high electromagnetic-shielding efficiency of 74.53 dB and sensitivity of 136.7 kPa⁻¹, while the thickness of the ACMF film was merely 54.73 μm. Excellent versatility could be attributed to the unique multi-stage layered structure of ACMF. This feature created synergistic EMI-shielding mechanisms and numerous conductive active contact sites, which resulted in the attenuation of electromagnetic waves and enhancement of sensor sensitivity efficiently. This work presents a facile and effective fabrication strategy for synthesizing ultrathin, highly conductive, and multifunctional nanocellulose/MXene flexible smart electronics films.