Morphology-Engineered Cu-Doped CeO₂ with Synergistic Defects for Enhanced Dielectric Polarization and Multifunctional Applications

The development of high-performance electromagnetic (EM) wave absorbers through morphology regulation and defect engineering remains a critical challenge. CeO2 nanoparticles have been extensively utilized in catalysis, energy, electromagnetic applications, and radiotherapy due to their unique redox surface chemistry, high stability, and biocompatibility. In this work, we systematically synthesized Cu-doped CeO2 with three distinct morphologies (nanorods, nanoparticles, and nanocubes) via a hydrothermal method to investigate their EM absorption mechanisms. Comprehensive characterization revealed that Cu-CeO2 nanorods (CuCe-NR) possess abundant oxygen vacancies and strong CuO-CeO2 interfacial interactions, which synergistically enhance dipole/interface polarization. Notably, CuCe-NR achieves exceptional EM absorption performance, with a reflection loss value of -40.98 dB (2.5 mm) and an absorption bandwidth of 4.72 GHz. The enhanced performance is attributed to optimized impedance matching enabled by the rod-like morphology and intensified dielectric loss from defect-induced polarization. In-situ DRIFTS further confirmed that high-index facets in CuCe-NR provide coordinatively unsaturated sites for polarization loss. This work elucidates the critical role of morphology-dependent defect engineering in designing advanced CeO2-based absorbers and provides a feasible strategy for lightweight, high-efficiency EM attenuation materials with antimicrobial properties.