In situ growth of TiO2 on Ti3C2Tx MXene for improved gas-sensing performances.

In this study, in situ prepared multiple semiconducting TiO 2 in a metallic Ti 3 C 2 T x channel were investigated, which were derived from the Ti 3 AlC 2 MAX phase by oxidation treatments. Several tiny TiO 2 particles were in situ formed on the Ti 3 C 2 T x MXene surface when it was heated to 150 °C at ambient conditions. The phase transformation of pristine Ti 3 C 2 T x MXene to oxidized TiO 2 was accelerated when the gas-sensing channel was heated to higher temperatures up to 200 °C, yielding a TiO 2 /Ti 3 C 2 T x composite. The experimental results revealed that the heat-treatment temperature played an important role in the gradual development of the morphology and gas-sensing activity of the TiO 2 /Ti 3 C 2 T x sensing channel. In particular, the optimal heating temperature of the composite resulted in a good response and recovery time for NO 2 molecules. Furthermore, first-principles calculations indicated the good sensing ability of the TiO 2 /Ti 3 C 2 T x composite for NO 2 than for other gases. These results suggest a new strategy for developing gas-sensing ability by forming a Schottky barrier through a simple process. [ABSTRACT FROM AUTHOR]