Simultaneously tuning structural defects and crystal phase in accordion-like Ti_(x)O_(2x−1)derived from Ti_(3)C_(2)T_(x)MXene for enhanced electromagnetic attenuation

Single Ti_(3)C_(2)T_(x)MXene(MTO)materials are not suitable for electromagnetic(EM)wave absorption due to their high conductivity and impedance mismatch.To address this issue,we ingeniously took advantage of easily oxidized characteristics of Ti_(3)C_(2)T_(x)MXene to establish structural defects and multiphase engineering in accordion-like TixO_(2x−1)derived from Ti_(3)C_(2)T_(x)MXene by a high-temperature hydrogen reduction process for the first time.Phase evolution sequences are revealed to be Ti_(3)C_(2)T_(x)MXene/anatase TiO_(2)→Ti_(3)C_(2)T_(x)MXene/rutile TiO_(2)→TixO_(2x−1)(1≤x≤4)during a hydrogen reduction reaction.Benefiting from conductance loss caused by hole motion under the action of an external electric field and heterointerfaces caused by interfacial polarization,the impedance match and EM attenuation capability of accordion-like TixO_(2x−1)absorbers derived from Ti_(3)C_(2)T_(x)MXene are superior to that of pristine Ti_(3)C_(2)T_(x)MXene/TiO_(2)materials.Additionally,simulated whole radar cross section(RCS)plots in different incident angular of the Ti_(3)C_(2)T_(x)MXene/rutile TiO_(2)product are lower than−20 dBm^(2),and the minimum RCS value can reach−43 dBm^(2),implying a great potential for practical applications in the EM wave absorption.Moreover,the relationship among charges,defects,interfaces,and EM performances in the accordion-like TixO_(2x−1)materials is systematically clarified by the energy band theory,which is suitable for the research of other MXene-derived semiconductor absorbing composites.