Superhydrophobic hierarchical hollow carbon microspheres for microwave-absorbing and self-cleaning two-in-one applications

Abstract

Advanced microwave absorbing materials with excellent microwave absorption properties and other fascinatingly additional functions continue to be highly sought after, while their fabrication still remains a huge challenge. Herein, through a facile and low-cost approach, we prepare a novel N-doped carbon microsphere with hierarchically micro-nano surface, multiporous shell, and hollow cavity to serve as a high-performance microwave absorbing material integrated with an exceptional superhydrophobicity. Specifically, the microwave absorption of the N-doped hollow carbon microspheres (N-HCMs) presents lightweight (a filler loading of 15 wt%), ultrastrong (a reflection loss of −61.2 dB), thin (a matching thickness of 1.45 mm), and very wide (an effective absorption bandwidth of 6.8 GHz) features. In particular, the absolute values of their specific reflection loss are far beyond the previously reported state-of-the-art carbon-based microwave absorbers with similar structures. Fascinatingly, the superhydrophobicity of N-HCMs is excellent and can tolerate the diversely harsh water-containing environments, which endows the microwave absorbing coatings with universally waterproof capacity as well as attractive self-cleaning function. We believe that this work can actively inspire the research of developing next-generation advanced microwave absorbing materials and pave the way for their multifunctional applications.