Tailoring hierarchical carbon nanotube cellular structure for electromagnetic interference shielding in extreme conditions

Abstract

Stable and resilient materials are in great demand for electromagnetic interference (EMI) shielding applications under extreme conditions. Here we present a facile method that could tailor and strengthen the pore structure of carbon nanotube (CNT) foams to obtain highly effective and reliable EMI absorbers that maintain their superior EMI effectiveness under heavy mechanical deformation and extremely high temperature. The hierarchical macro-to-micro pore structure and properties of CNT foam were tailored in a wide range via a secondary chemical vapor deposition (CVD) process. Benefiting from the multi-level reflection in hierarchical pore structures, the optimized CNT foam presents a high shielding efficiency (SE) of 84 dB and a specific SE (SSE/t) of 5.6 × 104 dB·cm2·g-1 in X-band. The tailoring process also provides outstanding stability and mechanical resilience, leading to 83.8% EMI SE maintained after 1000 compressive cycles. Moreover, the foams can keep 76.5% EMI SE after 30 min of 1000°C thermal-destruction process (in argon atmosphere). All these features demonstrate the potential of using the optimized CNT foam as an EMI shielding material under extreme conditions. These findings have essential inspiration for pore engineering in CNT-based EMI shielding materials, giving further guidance for the design of EMI shielding materials used in harsh conditions.