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) 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.