A core–shell Cu₂O@Cu-MOF for electromagnetic wave absorption and selective shielding

With the widespread adoption of emerging wireless technologies and devices, electromagnetic (EM) protection materials have become a global research focus. This study employs cuprous oxide (Cu₂O) cubes as templates and coats their surfaces with the conductive metal-organic framework (MOF)-copper hexahydroxytriphenylene (Cu-HHTP) to construct core-shell Cu₂O@Cu-HHTP. The material exhibits remarkable frequency-dependent EM characteristics, with both dielectric loss tangent and attenuation constant demonstrating peak values at 15.6 GHz that are considerably higher than those at other frequencies. Owing to these properties, Cu₂O@Cu-HHTP displays distinctive EM wave absorption and frequency-selective shielding capabilities. The material achieves a minimum reflection loss of -33.4 dB, with its effective EM wave absorption frequencies showing thickness-independent characteristics concentrated in the 13.6-17.0 GHz range. For EM shielding, it exhibits a shielding effectiveness difference of 19.8 dB and a transmission coefficient difference of 0.93. Furthermore, leveraging the superior EM attenuation of Cu₂O@Cu-HHTP, an EM energy conversion device is developed to harvest and reuse waste EM energy. This study not only expands the applications of conductive MOFs in EM protection, but also advances the development of high-performance EM protection materials with frequency-selective properties.