Size-regulated Co-doped hetero-interfaced 3D honeycomb MXene as high performance electromagnetic absorber with anti-corrosion performance

It is desirable to develop electromagnetic (EM) wave absorbers with anti-corrosion property that can suit various electronics, telecommunications, and military applications in harsh conditions. In this work, by varying the Co content in the 3D honeycomb MXene, Co/MXene composites with remarkable EM absorption performance were obtained. In particular, Co/MXene with 0.5 mmol Co displayed a minimum reflection loss (RL) of -54.3 dB at 2.34 mm and broad absorption bandwidth of 5.92 GHz at 2.02 mm. These Co/MXene composites also showed high resistance to corrosion as evidenced by very low corrosion current densities (10-6 - 10-7 A cm-2) and very large polarization resistances (107 - 108 omega) when exposed to various corrosive conditions (acid, neutral, and alkaline conditions). The unique honeycomb architecture and the combined presence of Co and MXene enabled the electron transfer from Co to MXene as revealed by density functional theory simulation and suppressed the contributions from magnetic and conductive losses, thus allowing only polarization loss-originated EM dissipation behavior. Accordingly, this study introduces a simplified model to elucidate the mechanism of EM absorption, offering insights at the nano level.