3D MXene Aerogel Frameworks With In Situ‐Grown BiFeO ₃ for Synergistically Enhanced Thermoelectric Performance

Three‐dimensional BiFeO 3 @MXene aerogel composites with enhanced thermoelectric performance were developed through in situ interfacial engineering. The MXene aerogel provides continuous electrical transport pathways and intrinsically low thermal conductivity, while uniformly grown BiFeO 3 delivers high thermopower and modulates carrier transport via heterointerfaces. As a result, the composites exhibit a significantly enhanced Seebeck coefficient while maintaining moderate electrical conductivity and reduced thermal conductivity. The optimized composite with a BiFeO 3 ‐to‐MXene mass ratio of 1:1 (B1M1) exhibited a Seebeck coefficient of 192.7 µV/K, an electrical conductivity of 181.3 S/cm, and a low thermal conductivity of 0.32 W/m∙K, leading to a maximum power factor of 612.1 µW/m∙K 2 and a peak figure of merit ( ZT ) of 0.53 at 400 K. In addition, the composite showed good environmental stability under humid air conditions and stable thermoelectric output at the device level. This study demonstrates that in situ growth of oxide phases within a 3D MXene aerogel is an effective strategy for overcoming thermoelectric trade‐offs and enabling the development of lightweight, high‐performance thermoelectric materials.