Three-Dimensional MoS₂/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 MoS₂, followed by freeze-drying is utilized to successfully fabricate a 3D MoS₂/MXene van der Waals heterostructure aerogel. The low-temperature synthetic approach effectively suppresses significant oxidation of the Ti₃C₂T_x MXene and results in a hierarchical and freestanding 3D heterostructure composed of high-quality MoS₂ and MXene nanosheets. Functionalization of MXene with a MoS₂ catalytic layer substantially improves sensitivity and long-term stability toward detection of NO₂ 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 HNO₂ formation on the MXene surface, due to the presence of MoS₂. 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.