Abstract: The introduction of built-in electric fields (BIEFs) has emerged as an effective strategy to boost electromagnetic wave absorption (EWA) performance. However, a single BIEF often fails to simultaneously achieve optimal impedance matching and sufficient dielectric loss. In this study, a series of Cu-ZnO/C (CZC) and hollow Cu-ZnO/C (HCZC) composites were fabricated using CuZn-ZIFs with varying Cu/Zn ratios as precursors through a tannic acid (TA)-assisted etching-reconstruction-calcination approach. The deliberate construction of dual Schottky contacts between Cu-ZnO and Cu-N-doped carbon (NC) effectively intensified the BIEF effect, thereby facilitating interfacial polarization and accelerating charge carrier separation. Concurrently, the incorporation of hollow architecture introduced abundant defects, hierarchical interfaces, and multiple scattering pathways, which jointly enhanced dielectric loss and optimized impedance matching. Furthermore, selective removal of ZnO from HCZC via sulfuric acid etching yielded hollow Cu/NC (HCC) composites, enabling the decoupling of contributions from dual Schottky contacts and hollow structural engineering to the overall EWA mechanism. Benefiting from their cooperative effects, the HCZC-3 sample exhibited superior EWA performance, achieving a minimum reflection loss (RL_min) of -43.38 dB at 2.5 mm and an effective absorption bandwidth (EAB) of 6.48 GHz, along with a radar cross-section (RCS) reduction of 34.51 dB m². This work provides a systematic elucidation of the distinct yet synergistic roles of hollow architectures and dual Schottky contacts in modulating impedance characteristics and dielectric losses, offering fresh insights into electromagnetic attenuation mechanisms governed by complex interfacial coupling.

Key words: Hollow structure, Dual Schottky contacts, Built-in electric field, Electromagnetic wave absorption, Multiple loss mechanism