Integration of helical carbon microcoils on toilet paper substrates for low-cost and broadband microwave absorption

Abstract

Carbon coils (CCs) based microwave absorbing materials (MAMs) have good application prospects in the field of microwave absorption (MA) due to its unique 3D spiral shape, excellent dispersibility and appropriate conductivity. However, CCs are gernerally grown on flat and hard substrates and subsequently be scraped from the substrates. The consumption of substates and the scraping process inevitably increase the preparation cost, which limits the large-scale production and application of CCs. Carbonized toilet paper (CTP) is not only a cheap and efficient MAMs, but also has ability of catalyst loading that makes it suitable as a substrate for CCs growth. Meanwhile, CTP and grown CCs can be used as MAM together without separating them from each other. These largely decrease the production cost. In this work, helical carbon microcoils (CMCs) were successful synthesized on CTP by Ni catalyzed chemical vapor deposition process. CTP and CMCs form an integrated absorbing composite, where the helical CMCs enhance conductive loss and cross polarization loss simultaneously, and the connections between CTP and CMCs induce the interface polarization loss. By precisely controlling the amount of catalyst, the impedance of CTP/CMC is adjusted. The optimized CTP/CMC-10 composite has excellent microwave absorption performance, with an effective bandwidth (reflection loss < −10 dB) of 7.4 GHz and a filling rate of 10 %. This work paves a new way for development of low-cost, broadband, and efficient MAMs.