High aspect-ratio sycamore biomass microtube constructed permittivity adjustable ultralight microwave absorbent

A novel permittivity adjustable ultralight microwave absorbent was achieved by constructing efficient high aspect-ratio Sycamore biomass microtube networks. [Display omitted] •High aspect-ratio CMT successfully synthesized derived from Sycamore biomass fiber.•ZnO/PCMT achieved great EAB performance at ultralow filler loading of 6.7 wt.%.•Such excellent EMW performance can be attributed to its unique 1D carbon microtube unit constructed network structure.•Heterogeneous structure constructed by columnar ZnO and carbon skeleton increases the interfacial polarization. Excessive conductivity of carbon-based materials led to poor impedance matching, hindering their electromagnetic absorbing application in aerospace and military fields. While, one-dimensional carbon materials are more favorable to build networks, satisfying impedance matching. One-dimensional carbon materials, such as carbon fibers, carbon nanotubes, carbon microtubes, etc., are recently limited by strict preparation and hard to industrialize. Inspired by the traditional handicraft of candied haw, ZnO/porous carbon micron tubes (ZnO/PCMT), are achieved by conducting a dip-coating and thermal etching process on recycling the abandoned Sycamore microtube. The prepared ZnO/PCMT exhibits higher specific surface area (1076m2g−1) and excellent microwave absorption performance. With a filler loading of only 6.7wt.%, the ZnO/PCMT achieved a great electromagnetic wave absorbing performance. Such excellent ultralight absorption performance can be attributed to their distinct hollow tubular structure of Sycamore based carbon microtube, which can easily construct conductive networks, improving the impedance matching. This work expands a new direction for the development of one-dimensional natural Sycamore microtube as ultra-light and broadband high-performance microwave absorbing materials.