SnO-SnO2 modified two-dimensional MXene Ti3C2Tx for acetone gas sensor working at room temperature

Acetone, as widely used reagents in industry and laboratories, are extremely harmful to the human. So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential. Herein, the nanocomposite combining SnO-SnO2 (p-n junction) and Ti3C2Tx MXene was successfully synthesized by a one-step hydrothermal method. Because of the existence of a small amount of oxygen during the hydrothermal conditions, part of the p-type SnO was oxidized to n-type SnO2, forming in-situ p-n junctions on the surface of SnO. The hamburger-like SnO-SnO2/Ti3C2Tx sensor exhibited improved acetone gas sensing response of 12.1 (Rg/Ra) at room temperature, which were nearly 11 and 4 times higher than those of pristine Ti3C2Tx and pristine SnO-SnO2, respectively. Moreover, it expressed a short recovery time (9 s) and outstanding reproducibility. Because of the different work functions, the Schottky barrier was formed between the SnO and the Ti3C2Tx nanosheets, acting as a hole accumulation layer (HALs) between Ti3C2Tx and tin oxides. Herein, the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti3C2Tx MXene in SnO-SnO2/Ti3C2Tx sensors was discussed in detail.