Revealing electrostatic-manipulated self-assembly mechanism helps to readily design enhanced MOF-derived microwave absorbers

Abstract

The controllable self-assembly of Metal Organic Frameworks (MOFs) crystals plays a vital role in modulating the performance for microwave absorbers. However, most current strategies require colloidal or intricate chemical modifications of nanoparticles, thereby increasing the complexity of structural construction and impeding the broader application of microwave absorbers. To resolve this tough issue, we herein innovatively propose a more easily achievable electrostatic-manipulated self-assembly strategy. By readily manipulating the electrostatic adsorption and repulsion between particles, the aggregation and growth sites of initial MOF crystals are anchored, hence facilitating to the construction of solid-core/shell and hollow porous microstructures for absorbers. The substantial improvement depending on electrostatic effects is clearly observed in experimental results. It demonstrates that the Co@hollow N-doped carbon spheres (Co@HNCSs) absorber, induced by electrostatic repulsion, shows the best overall absorption performance, with a strong absorption of −65.4 dB at a thickness of 1.9 mm and an effective absorption bandwidth (EAB) of 5.4 GHz at a thickness of 1.6 mm, covering almost the entire Ku band. The influence of these strategies on the electromagnetic response mechanisms is further comprehensively discussed. Accordingly, we believe this strategy offers new insights for the MOFs’ structural absorbers via electrostatic-manipulated self-assembly strategy.