Abstract: Layer engineering is widely applied in two-dimensional materials to achieve tunable and optimal properties. Graphene oxide (GO) nanosheets, as carbon-based carriers, offer various advantages for electromagnetic wave (EMW) absorption, including high specific surface area, tunable conductivity, and abundant polar functional groups. Nevertheless, the regulation of layer numbers of GO-based composite absorbents, and comprehensive understanding of the underlying mechanisms influencing the EMW absorption properties remain insufficient. This study converts ZIF-67/GO into Co/rGO composites, and employs the layer engineering via ultrasonic-assisted calcination, to investigate the influences of GO layer numbers on the material’s EMW absorption performance. In the optimized Co/rGO, few-layer GO forms a better conductive network, while the well-dispersed Co nanoparticles introduce magnetic loss and assist in achieving impedance matching. As a result, this sample delivers considerable absorption performance, with a minimum reflection loss of -49.86 dB and an effective absorption bandwidth of 5.35 GHz. Following additional heteroatom doping, the Co/rGO composite could further achieve an absorption efficiency of above 99.9999% (-68.02 dB), which efficiently reduce EMW signals from highly reflective targets to background noise level. This study confirms the effectiveness of layer engineering in regulating electromagnetic properties and thereby enhance the absorption performance of carbon-based composites to achieve strong and broadband EMW absorption.

Key words: Reduced graphene oxide (rGO), Layer engineering, Microwave absorption, Dielectric loss, Impedance matching