High-efficient photothermal conversion Ti3C2Tx/ionic liquid gel pen ink for breezily writing ultra-sensitive, wide range detective and flexible thermal sensors.

Photothermal conversion behavior has a vital application to disease therapy, water purification, or uncontacted heater. The fabrication of high performance photothermal conversion materials especially for near infrared (NIR) light and micro-structures has been attracted a great deal of attentions. Among numerous substances, MXene as a new type of 2D material with semi-metallic and unique electromagnetic properties presents a broaden absorption of light and even a typical plasmonic absorption near NIR-I area (808 nm), which has made it suitable for photothermal conversion. Here, we propose a facile approach for preparing a Ti3C2Tx-ionic liquid ink with high photothermal conversion efficiency. The as-prepared ink has showed the good wettability of various substrates, as well as the high sensitivity of 808 nm NIR light irradiation and a wide range of thermal variation. After packing the ink into a gel pen refill, the flexible thermal chips could be easily obtained just by pen writing on the soft surface with the designed size, which also have become an optimal candidate for thermal alarm system.