Integration of Thermal Insulation and X-Band Microwave Absorption in the Flexible and Resilient Hydrogenated TiO2 Ceramic Nanofibrous Sponges

Developing multifunctional materials that integrate microwave absorption, thermal insulation, ultralow density, and load-bearing capabilities is crucial for applications in complex environments. Herein, hydrogenated titanium dioxide nanofibrous sponges (H–TiO2 NFSs) featuring oxygen vacancies and heterogeneous interfaces were fabricated simply via electrospinning, followed by calcination and plasma treatment. The hydrogenation process modulated the band structure and introduced interfacial polarization, effectively enhancing the electromagnetic wave (EMW) attenuation performance. Consequently, the synthesized ceramic sponges exhibited a minimum reflection loss (RLmin) of −55.95 dB at 4.4 mm, with an effective absorption bandwidth of 4.2 GHz covering the X-band. Furthermore, the three-dimensional interconnected nanofibrous architecture endowed the H–TiO2 NFSs with ultralow density (0.047 g/cm3), low thermal conductivity (0.0356 W·m–1·K–1), and stable compressive resilience, including a residual strain of less than 18% after 100 cycles at 50% strain for H–TiO2-150 W. The as-obtained defect-engineered H–TiO2 NFSs are competitive candidates for thermal insulation and highly efficient X-band microwave absorption in harsh thermomechanical environments.