Carbon nanotube/cellulose papers with high performance in electric heating and electromagnetic interference shielding

A series of multi-walled carbon nanotube (MWCNT)-coated cellulose papers were manufactured by a facile dip-coating process, and their performance in electric heating and electromagnetic interference (EMI) shielding materials was investigated by considering the microstructure, thermal stability, and electrical property. With increasing the cycle of the dip-coating process, the apparent thickness of MWCNT/cellulose papers increased on a monotonic basis. It was observed that MWCNTs are coated dominantly on cellulose fibers on the paper surfaces, in addition to their partial coating on the inside of cellulose papers, which is supported by the anisotropic electrical conductivity of the papers in the in-plane or thickness direction. For MWCNT/cellulose paper obtained by single dip-coating cycle, high apparent electrical conductivity in the in-plane direction of 0.02 S/cm was achieved. The electrical conductivity in the in-plane direction increased significantly from 0.02 S/cm to 1.11 S/cm with increasing the dip-coating cycle from 1 to 30. Accordingly, MWCNT/cellulose papers with >1 dip-coating cycle exhibited excellent electric heating performance in terms of temperature responsiveness, steady-state maximum temperature, and electrical energy efficiency at constant applied voltages. In addition, high EMI shielding effectiveness of ∼20.3 dB (∼99.1% attenuation) was achieved at 1 GHz by MWCNT/cellulose paper with ∼1.11 S/cm and ∼170 μm only.