A synergistic route of heterointerface and metal single-atom configurations towards enhancing microwave absorption

Abstract

Derivatized multi-void composite microplates (CoNXC) were successfully fabricated for high-efficient electromagnetic wave absorption (EMA) using a two-step pyrolysis process assisted by molten dual-salt-mediated template. Structural analysis indicated that cobalt single atoms coexisted stably with Co nanoparticles in the derived carbon matrix, exhibiting the coupling of Co/graphite heterointerface. Various bonding configurations of Co/N atoms could be modulated by N-doping, in which the percentage of Co-NX single-atom coordination ranged from 18.58 % to 37.62 %, including CoN2, CoN3 and CoN4 configurations. Theoretical calculations demonstrated that the Co/graphite heterointerface and the Co single-atom configurations could significantly change the charge status and distribution, and synergistically promote dielectric polarization relaxation and electrons transport, which was in favor of strengthening the dielectric loss capacity. Benefiting from these, CoNXC remained high EMA performance even with filler loading of 10 wt%. In this regard, CoN20C exhibited strong RL peaks in multiple bands involving C-, X- and Ku-band, and its RLmin value reached −63.4 dB at 8.3 GHz, which were superior to most reported derivatized carbon-based composites. This work not only elucidates the synergistic mechanism of EMA by metal single-atom coordination and heterointerface, but also provides a new strategy for developing advanced carbon-based absorbers.