Simultaneously tuning structural defects and crystal phase in accordion-like Ti x O 2 x−1 derived from Ti 3C 2T x MXene for enhanced electromagnetic attenuation

The single Ti₃C₂T_x MXene material is not suitable for electromagnetic (EM) wave absorption due to its high conductivity and impedance mismatch. To address this issue, we ingeniously take advantage of easily oxidized characteristic of Ti₃C₂T_x MXene to establish structural defects and multiphase engineering in accordion-like Ti_xO_2x-1 derived from Ti₃C₂T_x MXene by the high-temperature hydrogen reduction process in the first time. The phase evolution sequences are revealed to be Ti₃C₂T_x MXene/anatase TiO₂ → Ti₃C₂T_x MXene/rutile TiO₂ → Ti_xO_2x-1 (1≤x≤4) during the hydrogen reduction reaction. Benefiting from the conductance loss caused by hole motion under the action of external electric field and heterointerfaces caused interfacial polarization, the impedance match and EM attenuation capability of accordion-like Ti_xO_2x-1 absorbers derived from Ti₃C₂T_x MXene are superior to that of pristine Ti₃C₂T_x MXene/TiO₂ material. Additionally, the simulated whole radar cross section (RCS) plots in the different incident angular of Ti₃C₂T_x MXene/rutile TiO₂ product is lower than -20 dBm² and the minimum RCS value can reach -43 dBm², implying a great potential for practical application in the EM wave absorption. Moreover, the relationship between charges, defects, interfaces, EM performances in accordion-like Ti_xO_2x-1 materials is systematically clarified by energy band theory, which is suitable for the research of other MXene-derived semiconductor absorbing composites.