Morphology-dependent magnetic role of ZIFs in nitrogen-doped MXene as metallic conductor microwave absorber

The suboptimal impedance matching characteristics exhibited by MXene, attributable to its elevated conductivity, in conjunction with the propensity of MXene flakes to agglomerate, has imposed significant limitations on the pragmatic applicability of MXene derivatives within the realm of electromagnetic wave (EMW) absorption. To decrease conductivity and induce dipolar polarization, the introduction of nitrogen-doped defects into a MXene (Ti₃C₂T_x) was accomplished by utilizing acetonitrile as a source of liquid nitrogen. The metallic conductivity of N-Ti₃C₂T_x at a nitrogen doping content of 5.31 at% has been uncovered through first-principles calculations. To mitigate the restacking of 2D MXene flakes and enhance their absorption performance in the low-frequency band, the insertion of magnetic intercalators has been implemented. The application of Co-Zn-coordinated zeolitic imidazole frameworks (ZIFs) as magnetic intercalators has demonstrated a substantial enhancement in polar units. The resulting structure of calcined ZIF-67@ZIF-8 showcases a hollow morphology and exhibits a high saturation magnetization, facilitating significant magnetic loss. For instance, ZIF-67@ZIF-8/N-Ti₃C₂T_x reaches the widest EBA of 5.36 GHz (2.273 mm, 13.00 GHz, R_Lmin = −65.03 dB), and the strongest value R_Lmin of −70.43 dB (3.350 mm, 7.64 GHz, EAB = 3.16 GHz), respectively. Furthermore, the present study employs COMSOL simulations to investigate the behavior of ZIF-67@ZIF-8/N-Ti₃C₂T_x in response to current field, as well as its electrical shielding attributes and EWM field patterns. This innovative multilayer microstructure effectively attains a desirable equilibrium between dielectric and magnetic properties, thereby showcasing immense promise in the domain of consecutive multi-band EMW absorption.