Bioinspired by staggered cellular structures: 3D-printed aerogel frameworks for ink rheological, parametric optimization, and enhanced terahertz electromagnetic shielding performance

With the rapid development of terahertz (THz) technology in ultra-high-speed communication and security inspection applications, there is a growing demand for high-performance THz shielding and absorbing materials to prevent electromagnetic interference (EMI) or pollution. Natural hierarchical staggered cellular structures, such as bones and wood, feature abundant micropores/channels and interlocking staggered layered architectures. The architectural feature promotes multi-reflection and absorption of electromagnetic waves, prolonging their propagation path and strengthening wave attenuation. Inspired by this, a bioinspired strategy was proposed to fabricate multilayer-MXene (m-Ti₃C₂T_x)/cellulose nanofibrils (CNFs) aerogel frameworks with staggered stacking architectures via direct ink writing (DIW) three-dimensional (3D) printing technology for enhanced THz shielding and absorption performance. Through comprehensive optimization, we achieved composite inks with outstanding rheological properties and identified optimal printing parameters, enabling high-precision and stable 3D printing fabrication. The framework exhibits an excellent maximum reflection loss (RL) of 54.01 dB in the 0.5–3.0 THz range (100% qualified bandwidth) and a high absorption of 99.40%. It realizes a high green shielding index (g_s), the range of g_s > 9 that meets the standard for excellent green EMI shielding up to 2.5 THz. Meanwhile, it demonstrates high shielding effectiveness (SE) exceeding 40 dB across a broad gigahertz (GHz) frequency range from 3.9 to 18 GHz, particularly reaching an excellent 101.84 dB in the Ku band. This work provides a simple and efficient way to achieve outstanding THz shielding and absorption performance.