Comparative enhancement of H ⁺ and OH ⁻ treatment on electromagnetic interference shielding in aligned and compact Ti ₃ C ₂ T _<i>x</i> MXene film

Abstract The pressing demand for ultrathin and flexible shields to counter electromagnetic interference (EMI) has sparked interest in Ti 3 C 2 T x MXene materials due to their exceptional electrical conductivity, tunable surface chemistry, and layered structure. However, pure Ti 3 C 2 T x MXene films often lack the mechanical properties required for practical engineering applications, and traditional reinforcement methods tend to reduce electrical conductivity. This work demonstrates an effective strategy to enhance the alignment and densely packed layered structure of Ti 3 C 2 T x MXene films by regulating the acidity and alkalinity of Ti 3 C 2 T x MXene aqueous solutions. This approach simultaneously improves mechanical strength and electromagnetic interference shielding effectiveness (EMI SE). Compared with original Ti 3 C 2 T x MXene films, MXene films modified with ammonia solution (NH 3 ·H 2 O) via OH − show a significant improvement in tensile strength (27.7 ± 1.9 MPa). Meanwhile, MXene films treated with hydrochloric acid (HCl) via H + reach an even higher tensile strength of 39 ± 1.5 MPa. Moreover, the EMI SE values of the treated MXene films increase significantly, each reaching 66.2 and 58.4 dB. The maximum improvements in EMI SE values for the acid‐ and alkali‐treated samples are 17.9% and 4%, respectively. In conclusion, the simultaneous enhancement of mechanical strength and EMI shielding efficacy highlights the potential of acid‐ and alkali‐treated Ti 3 C 2 T x MXene films for applications in ultrathin and flexible EMI shielding materials.