Design And Development Of Ti₃C₂ MXene-based Gas Sensing Components

The design and development of high-performance gas sensors that can operate at room temperature still faces a huge challenge.2D Ti₃C₂T_x MXene has shown great potential in the field of room temperature gas sensing due to its metal conductivity,high specific surface area and rich surface functional groups.However,the gas sensors made of pristine Ti₃C₂T_xMXene usually have some problems,such as low sensitivity,poor selectivity,serious baseline resistance drift and poor environmental stability.Therefore,this paper improves the gas sensitivity of the pristine Ti₃C₂T_x MXene by combining metal oxide and noble metal.The specific work contents are as follows:（1）The novel 3D Fe₂O₃/Ti₃C₂T_x derived Ti O₂ hierarchical heterostructure was prepared by hydrothermal treatment and chemical bath deposition.Firstly,using the HF etching method and hydrothermal method,multilayer Ti₃C₂T_x MXene was prepared.Then,the Fe₂O₃nanoflowers were grown in situ on Ti₃C₂T_x-derived Ti O₂ nanoflakes by water bath deposition.With its unique structure,2D Ti₃C₂T_x derived Ti O₂ nanoflakes provided a very ideal platform for the nucleation and growth of Fe₂O₃ nanoflowers.The growth and evolution of Fe₂O₃ nanoflowers on Ti₃C₂T_x-derived Ti O₂ nanoflakes can be effectively regulated by simply controlling the water bath deposition time.The gas sensitivity test results indicate that the Fe₂O₃/Ti₃C₂T_x derived Ti O₂ sensor prepared under the water bath deposition time of 45 minutes shows the highest response value of 48.6%to 10 ppm H₂S.In contrast,Fe₂O₃ and Ti₃C₂T_x derived Ti O₂ sensors have little response to 50 ppm H₂S.In addition,the Fe₂O₃/Ti₃C₂T_x derived Ti O₂ sensor also has very high selectivity for H₂S gas,low detection limit（200 ppb）and good repeatability.（2）The Ti₃C₂T_x-Ti O₂ gas sensor decorated by Pt NPs was designed reasonably for NH₃gas detection at room temperature.Firstly,the multilayer Ti₃C₂T_x MXene was prepared by Li F and HCl etching method,and then the multilayer Ti₃C₂T_x was decomposed into monolayer Ti₃C₂T_x nanoflakes by ultrasonic method,and then the Ti₃C₂T_x-Ti O₂ composite was prepared by hydrothermal method.Since there are two competing sensing paths within the Ti₃C₂T_x-Ti O₂ material:metal Ti₃C₂T_x and semiconductor Ti O₂,respectively,responsible for carrier scattering and charge doping after gas adsorption.In order to fully utilize the synergistic effects between Ti₃C₂T_x and Ti O₂ and obtain the best NH₃ response,the content of Ti O₂ in Ti₃C₂T_x-Ti O₂ composites was controlled by controlling the hydrothermal oxidation time.The gas sensitivity test results show that the Ti₃C₂T_x-Ti O₂ composite obtained by hydrothermal treatment for 8 hours has the highest NH₃ response value.Finally,the Pt NPs were decorated on the Ti₃C₂T_x-Ti O₂ composite obtained by hydrothermal treatment for 8 hours to further improve its gas sensitivity.The results showed that the Pt decorated Ti₃C₂T_x-Ti O₂ gas sensor showed a high response of 13%to 5 ppm NH₃.