Facile solvothermal synthesis of novel hetero-structured CoNi–CuO composites with excellent microwave absorption performance

Abstract

Hetero-structured functional materials with tailored composition that can provide excellent electromagnetic wave (EMW) absorption with minimal thickness are highly desirable, especially if they can be easily fabricated. Herein, novel hetero-structured CoNi–CuO composite microspheres were fabricated via a facile solvothermal process. The composites with adjusted mass ratios of CuO to CoNi alloy (5/1, 2.5/1 and 1.25/1) were facilely achieved by modulating the quantity of CuCl₂·2H₂O during the synthesis. It was demonstrated that the enhanced microwave absorption properties could be ascribed to the dielectric CuO, which can favorably increase the interface of the hetero-structure and the impedance matching with CoNi alloyed particles. It was shown that, when the molar ratio was 2.5 : 1, the typical CoNi–CuO composite microspheres presented a promising microwave absorption performance, namely a maximum reflection loss (RL) of −25.1 dB at 13.2 GHz with a thickness of only 2.5 mm, while the effective microwave absorption bandwidth (RL < −10) could reach 3.4 GHz (from 10.0 to 13.4 GHz). As is demonstrated, this kind of newly fabricated CoNi–CuO composite can be regarded as a promising candidate for high-performance microwave absorption materials.