Enhanced Electromagnetic Absorption of Cement Composites by Controlling the Effective Cross-sectional Area of MXene Flakes with Diffuse Reflection Based on Carbon Fibers

We studied the potential application of MXene flakes for electromagnetic interference (EMI) shielding in cement matrices. Despite their superior electrical and shielding properties, MXene flakes cannot be used in cement for building construction owing to the poor effective cross-sectional area, which is induced by low concentrations and random orientations of small MXene flakes. This reduced the MXene effect on EMI shielding, which could be compensated by co-inserting carbon fibers for diffuse reflections, recovering the reduced effective cross-sectional area of MXene flakes for incident EM waves. Even with a small amount (0.5 wt%) of MXene with 2.5 wt% of carbon fibers, the shielding effectiveness (SE) of cement composites was enhanced to 41.35 dB at 1.0 GHz at a thickness of 3 mm, which is 800 % enhanced compare with the cement composite only with MXene (3.0 wt%). Scanning electron microscopy and permittivity measurements were performed after SE measurements to further analyze the multi-interface structure in detail. This synergetic EMI SE enhancement behavior caused by adding layered materials can be an efficient way to improve the SE of constructing materials with applicable fluidity to form building construction.