Gallium-doped MXene/cellulose nanofiber composite membranes with electro/photo thermal conversion property for high performance electromagnetic interference shielding

With the rapid development of science and technology, information security and multiscenario applications of electronic equipment have received increasing attention in recent years. Therefore, the design and development of multifunctional electromagnetic interference shielding materials are key to solving the current development needs of electronic equipment. Based on the above topics, multifunctional liquid metal gallium (Ga)-doped transition metal carbides/nitrides (MXenes)/cellulose nanofiber (CNF/MXene@Ga, CMG) composite membranes with a nacre-like “brick–mortar” layered structure were synthesized using an ultrasonic probe and vacuum-assisted filtration. By optimizing the design, the CMG composite membranes could achieve a tensile strength of 36.12 MPa with good flexibility and could achieve a maximum thermal conductivity of approximately 9.11 W/m·K. The heterogeneous interface between MXenes and Ga nanoparticles and the intercalation of Ga nanoparticles significantly influenced the composite membranes for the absorption of electromagnetic waves, which yielded a specific shielding effectiveness per unit volume (SSE/t) of 6444.1 dB·cm2·g−1; this value is over the vast majority reported in the current literature. Further studies confirmed that the CMG composite membranes possessed excellent electrothermal and photothermal conversion functions. The electrothermal conversion agreed with Joule's law. Moreover, the phase transition behavior of Ga also imparts the membranes with the ability to store heat. The photothermal conversion ability was attributed to the surface plasmon resonance effect of Ga. Therefore, this work provides material support for the information security and multi-scenario applications of electronic equipment.