High‐Temperature Reduced MXene/rGO/Ni Layered Composite Films for EMI Shielding and Photothermal Conversion

Ammonia‐assisted high‐temperature reduction is exploited to create ultrathin (23.7 µm) MXene/reduced graphene oxide/Ni (MXene/rGO/Ni) composite films in which monodisperse metallic Ni nanoparticles are nanosoldered between conductive nanosheets. The single‐step protocol simultaneously deoxygenates graphene oxide (GO), restores the MXene basal plane, and reduces Ni ²⁺ , generating an intact yet flexible layered scaffold with a through‐plane electrical conductivity of 3.3 × 10 ³ S m ⁻¹ and sheet resistance as low as 4.5 Ω sq ⁻¹ . The reconstructed heterointerfaces supply abundant dipole polarization centers and magnetic dissipation sites, endowing the film with an X‐band electromagnetic interference shielding effectiveness (EMI SE) of 35.1 dB that operates through a synergistic reflection absorption mechanism (reflection coefficient R ≈ 0.9, absorption shielding effectiveness SE _A ≈ 24.9 dB). Benefiting from the dense conductive network, the film enables efficient photothermal conversion and delivers linearly tunable photothermal response with excellent cycling stability. Mechanical tensile tests give an ultimate strength of 7.4 MPa, Young's modulus of 0.97 GPa, and toughness of 31.19 KJ m ⁻³ for rMG/Ni‐600 films. The aqueous fabrication route and excellent batch‐to‐batch reproducibility highlight the reliability of MXene/rGO/Ni homogeneous layers as lightweight, multifunctional shields for flexible electronics and high‐temperature photothermal‐management platforms.