Eutectic Molten Salt-Enabled Large-Scale Ti ₃ AlC ₂ MAX Phase Synthesis for High-Performance Ti ₃ C ₂ T _X MXene Transparent Heaters and Breath Sensors

Despite previous research, acquiring large-scale Ti₃AlC₂ MAX particles using the molten salt method is still a challenge. In this study, large-scale Ti₃AlC₂ MAX particles of 10-37 μm were synthesized for the first time using eutectic molten salt at 1300 °C, 4 h sintering. The increased crystal size of Ti₃AlC₂ MAX achieved using eutectic molten salt led to the production of 3-12 μm Ti₃C₂T_X MXene. The transparent heater and textile-based breath sensor fabricated from the as-prepared Ti₃C₂T_X MXene show good performance due to the large size of MXene. The best heating efficiency of 148.2 °C cm² W^-1 was achieved in Ti₃C₂T_X MXene thin film of <i>R</i>_<i>s</i> = 212.16 Ω sq^-1 and <i>T</i> = 73.76% at 550 nm. The textile-based breath sensor shows a fast response to humidity and good linear correlation (<i>r</i>^<i>2</i> = 0.9972) between relative humidity and current and exhibits a low device resistance of 3.153 KΩ at 40% RH. A maximum resistance response of 262.4% was achieved at 93% RH using 5% RH as the initial condition. This work successfully demonstrates for the first time the practicality of Eut-Ti₃AlC₂ as a potential alternative to commercial Ti₃AlC₂ MAX for the application to transparent heaters and breath sensors that require large size MXene.