Ion selectivity regulation under confinement for electromagnetic pollution management

Abstract

Ionic conductors are emerging as promising candidates in the field of microwave absorption, demonstrating significant potential in absorption efficiency and practical applications. In this study, we have synthesized a series of microwave absorption clays (AC) by incorporating 2D ZIF-L with four imidazolium ionic liquids (ILs). These materials not only exhibit outstanding absorption properties but also enhance our understanding of mechanisms associated with ion-based absorbers. The selective interaction of the ZIF-L framework results in distinct dielectric properties among imidazolium ILs with varying ion sizes and polarities. Analysis of relaxation behavior and ionic conductivity reveals that smaller ions facilitate better ionic transport and longer relaxation times by accessing the interior cavities, whereas larger ions experience extended charge transport distances within the framework gaps but shorter relaxation times due to the formation of short-range ordered structures. Moreover, these clay-like ionic conductors demonstrate excellent microwave absorption capabilities, with effective bandwidths of 2.3 GHz, 7.0 GHz, 6.7 GHz, and 7.4 GHz, respectively. This work presents a promising avenue for high-performance absorbers, advancing our understanding of ion-based absorption mechanisms.