Nitrogen-Doped Ti₃C₂T_<i>x</i> MXene Induced by Plasma Treatment with Enhanced Microwave Absorption Properties

Ti₃C₂T_<i>x</i> has microwave absorption (MA) properties due to its dielectric loss, but the absence of magnetic loss capability of pure Ti₃C₂T_<i>x</i> causes unmatched impedance and unsatisfied MA performance. Modification of Ti₃C₂T_<i>x</i> with magnetic particles is an effective way to introduce the magnetic loss mechanism. However, these modified Ti₃C₂T_<i>x</i> particles have higher density and require complicated fabrication processes, restricting the industrial production and functional applications. Here, a low-temperature and simple method of radio-frequency N₂ plasma treatment was adopted to modify Ti₃C₂T_<i>x</i> with N. More interestingly, the N-doped Ti₃C₂T_<i>x</i> flakes demonstrated magnetic properties and thus exhibited drastically enhanced MA properties. The minimum reflection loss (RL_min) of -59.20 dB at 10.56 GHz was achieved in N-doped Ti₃C₂T_<i>x</i> products after only 3 min of plasma treatment, remarkably higher than RL_min of -11.07 dB at 7.92 GHz for the pristine Ti₃C₂T_<i>x</i>. The main mechanism is due to the combination of dielectric loss, magnetic loss, and the good impedance matching in the N-doped Ti₃C₂T_<i>x</i>. Further prolonging the nitriding time induces much desorption of -F and the formation of TiO₂, thus deteriorating the impedance matching and the MA properties.