Abstract: Although MXene sheets possess high electrical conductivity and rich surface chemistry and are well suitable for fabricating electrically conductive nanocomposites for electromagnetic interference (EMI) shielding applications, it remains challenging for MXene nanocomposites to achieve tunable EMI shielding performances and customized geometries. Herein, an aqueous MXene/sodium alginate ink is developed to print aerogel meshes with customized geometries using a direct ink writing approach. An ion-enhanced strategy is proposed to reinforce the printed aerogel meshes by multi-level cross-linking. The resultant 3D printed aerogel mesh exhibits an ultrahigh electrical conductivity of 2.85×10³S m^-1, outstanding mechanical properties, and excellent structural stability in wet environment. More importantly, a wide range of tunable EMI shielding efficiencies from 45 to 100 dB is achieved by the structural design of the 3D printed ion-enhanced MXene/sodium alginate aerogel meshes. As a Joule heater, in addition, the printed aerogel meshes can achieve a wide temperature range of 40-135 °C at low driving voltages. This work demonstrates a direct ink writing approach for the fabrication of ion-enhanced MXene/sodium alginate aerogel meshes with tunable EMI shielding properties and multi-functionalities for applications in many scenarios.

Key words: MXene inks, Aerogels, Electromagnetic interference shielding, Direct ink writing, Joule heating