Synthesis of Stable 2D Conductive Lanthanide Organic Frameworks (Lu-HHTP) for High-Performance Humidity Sensors

Two-dimensional conductive metal-organic frameworks (MOFs) featuring structural diversity and high porosity represent promising platforms for chemiresistive humidity sensing. The precise control of the structure of lanthanide-based MOFs and an exploration of its impact on charge transport and sensing applications have consistently been focal points for researchers. In this study, we present the synthesis and characterization of Lu-HHTP (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene) as highly crystalline and conductive porous materials. The polymeric framework of Lu-HHTP encompasses 1D hexagonal channels and exhibits interlayer π–π stacking, resulting in a material with a high surface area and uniform rod-like microstructure. Benefiting from its elevated electrical conductivity, the Lu-HHTP-based humidity sensor exhibited commendable sensing properties within the relative humidity range of 33 % to 95 % at room temperature (25 °C), achieving a response value as high as 19 at 95 % relative humidity. Furthermore, the sensor displayed superior repeatability, characterized by rapid response and recovery speeds in the presence of moisture. These findings indicate that Lu-HHTP holds substantial promise as a material for humidity sensors.