Ti3C2T x Supported Cu3(HHTP)2 Nanorod Arrays for High-Performance Hydrazine Hydrate Detection

Abstract Two-dimensional conductive metal–organic frameworks (2D-cMOFs) hold significant potential for gas-sensing applications, but their aggregation issues prevent high gas-sensing performance at room temperature (RT). To overcome this bottleneck, a Ti3C2Tx nanosheet was used to in situ support Cu3(HHTP)2 nanorod arrays to build a Cu3(HHTP)2/Ti3C2Tx heterostructure, in which the introduced Ti3C2Tx nanosheet not only promotes oriented growth of Cu3(HHTP)2 nanorod arrays but also facilitates interfacial charge transfer. Consequently, the active surface exposure of Cu3(HHTP)2 nanorods and gas diffusion pathways are maximized, further enhancing the detection performance toward hydrazine hydrate (N2H4) gas. Gas-sensing tests reveal that a response time is only 2.3 min to 20 ppm of N2H4 gas, and the actual lowest detectable concentration is down to 1 ppm at RT. Under 200 ppm of N2H4 gas exposure, its response value reaches approximately seven times that of the original Cu3(HHTP)2 sensor. The sensing mechanism of the Cu3(HHTP)2/Ti3C2Tx heterostructure toward N2H4 gas was elucidated through electrochemical impedance spectroscopy (EIS) data, in conjunction with density functional theory (DFT) calculations. This work presents a promising strategy for the heteroepitaxial growth of c-MOF nanorod arrays and paves the way for their application in the sensing of N2H4.