Rational construction of hierarchical hollow CuS@CoS₂ nanoboxes with heterogeneous interfaces for high-efficiency microwave absorption materials

Hierarchical hollow structures have received considerable attention for light weight microwave absorption materials, however, constructing and regulating hollow structures with heterogeneous interfaces still remains a great challenge. In this work, hierarchical hollow CuS@CoS₂ nanoboxes with double shells have been designed by a template-assisted process inspired by Pearson's hard and soft acid-base principle, in which the hollow nanoboxes are composed of CuS inner shell and CoS₂ nanosheets outer shell. The formation of outer Co(OH)₂ nanosheets is a key factor to achieve the double shells via a “coordinating etching and precipitating” route and the etching of cubic Cu₂O precursor plays an important role to stabilize the hollow nanoboxes. As absorbers, the hierarchical hollow nanoboxes exhibit high-efficiency microwave absorption attenuation because of the synergistic effects of dipolar and interfacial polarizations, multiple scatterings, hollow/core-shell structures and matched impedance. Typically, the minimum reflection loss is up to −58.6 dB at 2.5 mm when the filler loading is 20 wt% and the absorption bandwidth exceeding −10 dB is 8.2 GHz at 2.2 mm with 30 wt% filler loading. Consequently, this strategy offers a unique thought for the construction of hollow nanoboxes with double shells and the as-fabricated nanoboxes can be used as a promising candidate for microwave absorption materials with light weight and high-efficiency.