Hierarchical Ti3C2Tx@ZnO Hollow Spheres with Excellent Microwave Absorption Inspired by the Visual Phenomenon of Eyeless Urchins

Abstract

Ingenious microstructure design and rational composition selection are effective approaches to realize high-performance microwave absorbers, and the advancement of biomimetic manufacturing provides a new strategy. In nature, urchins are the animals without eyes but can "see", because their special structure composed of regular spines and spherical photosensitive bodies "amplifies" the light-receiving ability. Herein, inspired by the above phenomenon, the biomimetic urchin-like Ti₃C₂T_x@ZnO hollow microspheres are rationally designed and fabricated, in which ZnO nanoarrays (length: ~ 2.3 μm, diameter: ~ 100 nm) as the urchin spines are evenly grafted onto the surface of the Ti₃C₂T_x hollow spheres (diameter: ~ 4.2 μm) as the urchin spherical photosensitive bodies. The construction of gradient impedance and hierarchical heterostructures enhance the attenuation of incident electromagnetic waves. And the EMW loss behavior is further revealed by limited integral simulation calculations, which fully highlights the advantages of the urchin-like architecture. As a result, the Ti₃C₂T_x@ZnO hollow spheres deliver a strong reflection loss of - 57.4 dB and broad effective absorption bandwidth of 6.56 GHz, superior to similar absorbents. This work provides a new biomimetic strategy for the design and manufacturing of advanced microwave absorbers.

Keywords: Bioinspired; Hierarchical heterostructures; Microwave absorption; Ti3C2Tx MXene; ZnO nanoarrays.

Scheme 1

Schematic illustration of the synthesis process of urchin-like Ti₃C₂T_x@ZnO hollow spheres

Fig. 1

SEM images for a Ti₃C₂T_x-450, b Ti₃C₂T_x-550, and c Ti₃C₂T_x-650; d the corresponding elemental mapping of Ti₃C₂T_x-650; e XRD Patterns of Ti₃C₂T_x and Ti₃C₂T_x hollow spheres; TEM images for f Ti₃C₂T_x-450, g Ti₃C₂T_x-550, and h Ti₃C₂T_x-650

Fig. 2

a, b SEM images for PMMA@Ti₃C₂T_x@ZnO and d the corresponding elemental Mapping; e, f high-resolution TEM images for Ti₃C₂T_x@ZnO-650; SEM images for g Ti₃C₂T_x@ZnO-450, h Ti₃C₂T_x@ZnO-550, and i, j Ti₃C₂T_x@ZnO-650; k the elemental Mapping of Ti₃C₂T_x@ZnO-650; c XRD patterns of PMMA@Ti₃C₂T_x@ZnO and Ti₃C₂T_x@ZnO hollow spheres

Fig. 3

Frequency dependence of reflection loss for Ti₃C₂T_x hollow spheres and Ti₃C₂T_x@ZnO hollow spheres: a, b Ti₃C₂T_x-450, c, d Ti₃C₂T_x-550, e, f Ti₃C₂T_x-650, g, h Ti₃C₂T_x@ZnO-450, i, j Ti₃C₂T_x@ZnO-550, and k, l Ti₃C₂T_x@ZnO-650

Fig. 4

a Comparison of RL_min and EAB of Ti₃C₂T_x hollow spheres and urchin-like Ti₃C₂T_x@ZnO hollow spheres; b SRL and EAB of ZnO-based composites; d Complex electric field intensity distribution and e electric energy loss distribution; c, f Schematic illustration of microwave absorption mechanisms for urchin-like Ti₃C₂T_x@ZnO hollow microspheres