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.