Carbon Microtube/NiCo Carbonate Hydride Nanoneedle Composite Foams for Broadband Electromagnetic Interference Shielding

Broadband electromagnetic interference (EMI) shielding materials with flexible, ultralight, and ultrahigh performance are badly needed for application in high-tech fields. Taking inspiration from the lightning rod, a CMT-NiCoCH hybrid foam with bimetallic (Ni, Co) carbonate hydroxide (NiCoCH) needle structure in the nanoscale was designed. It was demonstrated that the superiority of the lightning rod effect is beneficial for EMI shielding materials to achieve excellent EMI shielding performance. It was found that by guiding electron migration along the tip direction, NiCoCH nanoneedles with sharp tips can induce a lightning rod effect, which accelerates charge transfer and separation. During this process, the electromagnetic waves (EMWs) that enter the interior of the CMT-NiCoCH hybrid foam are consumed, thereby increasing the absorption EMI shielding effectiveness. As a result, the CMT-NiCoCH hybrid foam exhibits an EMI SE of up to 68.7 dB in the broadband of 8.2–40 GHz (covering the X, Ku, K, and Ka bands). The application of the lightning rod effect offers interesting opportunities in the field of EMW energy consumption, opening up directions in the structural design of advanced EMI shielding materials and even EMW absorption materials by controlling charge transfer and separation processes to obtain efficient energy consumption.