Three-Dimensional MoS 2 /MXene Heterostructure Aerogel for Chemical Gas Sensors with Superior Sensitivity and Stability.

The concept of integrating diverse functional 2D materials into a heterostructure provides platforms for exploring physics that cannot be accessed in a single 2D material. Here, physically mixing two 2D materials, MXene and MoS ₂ , followed by freeze-drying is utilized to successfully fabricate a 3D MoS ₂ /MXene van der Waals heterostructure aerogel. The low-temperature synthetic approach effectively suppresses significant oxidation of the Ti ₃ C ₂ T _x MXene and results in a hierarchical and freestanding 3D heterostructure composed of high-quality MoS ₂ and MXene nanosheets. Functionalization of MXene with a MoS ₂ catalytic layer substantially improves sensitivity and long-term stability toward detection of NO ₂ gas, and computational studies are coupled with experimental results to elucidate that the mechanism behind enhancements in the gas-sensing properties is effective inhibition of HNO ₂ formation on the MXene surface, due to the presence of MoS ₂ . Overall, this study has a great potential for expansion of applicability to other classes of two-dimensional materials as a general synthesis method, to be applied in future fields of catalysis and electronics.