Au- and Pt-decorated Ti₃C₂Tx MXenes for preparing self-heated and flexible NH₃ gas sensors

In this study, Au- and Pt-decorated Ti3C2Tx MXene gas sensors were used for NH3 sensing. Initially, Ti3C2Tx MXene was synthesized from Ti3AlC2 MAX by a simple HF etching. Then, various amounts of Au or Pt NPs were decorated on Ti3C2Tx MXene using sodium borohydride. The characterization results showed that separated MXene nanosheets were prepared after etching and Au or Pt NPs were successfully decorated on them. The sensors could operate at room temperature in the self-heating mode. The sensors with 1.92 at% Au or 0.83 at% Pt NPs showed good selectivity for NH3 gas. In addition, 1.92 at% Au- and 0.83 at% Pt-decorated gas sensors could work under 5 and 3 V applied voltages, respectively. The flexibility of both gas sensors was demonstrated by bending and tilting of the sensors for 5000 and 1000 times, respectively. The formation of Au/MXene or Pt/MXene Schottky junctions and the catalytic effect of noble metals accounted for the good performance to NH3 gas. The obtained results can facilitate the progress of self-heated and flexible gas sensors using Ti3C2Tx-based gas sensors.