# Multiscale Design of Dual-Gradient Metamaterials Using Gel-Mediated 3D-Printed Graphene Aerogels for Broadband Electromagnetic Absorption

## TL;DR

This paper introduces a 3D-printed graphene aerogel that efficiently absorbs electromagnetic waves across a broad frequency range while being lightweight.

## Contribution

A novel gel-mediated 3D printing strategy for dual-gradient metamaterials with enhanced electromagnetic absorption is proposed.

## Key findings

- The rGO/PAA aerogel achieves a reflection loss of −39.86 dB and 8.36 GHz absorption bandwidth at low density.
- A metamaterial absorber with 14 GHz effective absorption bandwidth is realized across C, X, and Ku bands.
- The method enables precise control of rheology and dielectric loss in graphene composites for lightweight EWA materials.

## Abstract

The rGO/PAA aerogel achieves synergistic optimization for direct ink writing printing and construction of 0D/2D heterostructures in rGO sheets.Optimal reflection loss of −39.86 dB and effective absorption bandwidth (EAB) of 8.36 GHz are obtained with low density of 4.8 mg cm−3.Realization of an ultra-broadband metamaterial absorber of 14 GHz EAB at 7.8 mm thickness, across the C, X, and Ku bands.

The rGO/PAA aerogel achieves synergistic optimization for direct ink writing printing and construction of 0D/2D heterostructures in rGO sheets.

Optimal reflection loss of −39.86 dB and effective absorption bandwidth (EAB) of 8.36 GHz are obtained with low density of 4.8 mg cm−3.

Realization of an ultra-broadband metamaterial absorber of 14 GHz EAB at 7.8 mm thickness, across the C, X, and Ku bands.

The online version contains supplementary material available at 10.1007/s40820-025-02005-7.

Three-dimensional (3D)-printed graphene aerogels hold promise for electromagnetic wave absorption (EWA) engineering due to its ultralow density, outstanding electromagnetic dissipation with the flexibility and precision of manufacturing strategies. However, their high conductivity causes severe impedance mismatch, limiting EWA performance. 3D printing requirements also constrain the dielectric properties of printable graphene inks, hindering the integration of high-performance absorbers with advanced manufacturing. This study proposes a polyacrylic acid (PAA) gel-mediated 3D porous graphene oxide (GO) aerogel multiscale regulation strategy. Precise gel content control enables dual-gradient tuning of the rheology (Benefiting direct ink writing (DIW)) and dielectric loss (Enhancing EWA) of GO/PAA composites and reduces aerogel density (6.9 mg cm−3 from 28.2 mg cm−3). Thermal reduction decomposes PAA into amorphous carbon nanoparticles anchored on reduced graphene oxide (rGO), enhancing impedance matching and absorption via synergistic 0D/2D interfacial polarization and conductive loss. The optimized rGO/PAA aerogel achieves a minimum reflection loss (RL) of −39.86 dB at 2.5 mm and an effective absorption bandwidth (EAB) of 8.36 GHz (9.64–18 GHz) at 3.2 mm. Combining DIW and this aerogel, we design a metamaterial absorber (MA) with dual material (dielectric loss) and structural gradients. This MA exhibits an ultrawide EAB of 14 GHz (4–18 GHz) with a total thickness of 7.8 mm. This work establishes a coupled design paradigm of “composition-structure-performance,” providing an engineerable solution for developing lightweight, broadband EWA materials.

The online version contains supplementary material available at 10.1007/s40820-025-02005-7.