Incorporating Au nanoparticles into metal-organic framework for low humidity sensors

Abstract

Locating high active metal species into idea support surface to form spatially integrated nanostructure is essential for the adsorption and excitation process of water molecules. In this work, we proposed a spatial confinement strategy through incorporating Au nanoparticles into metal-organic framework (MOF) to realize low humidity sensing detection. We found the porous nature of MOF-303 morphology can provide confined room to induce Au species accumulation around the high active hydrophilic pocket (composed by three μ2-OH groups and two N(H)). In-situ Raman results further indicate the spatially-close Au species and hydrophilic pocket sites could synergistically promote chemical adsorption of water molecules and proton transfer processes. The as-fabricated Au@MOF-303 humidity sensor exhibits ultra-high response at low humidity condition (4345 Hz to 3.39 % RH), low humidity hysteresis (0.18 % RH), excellent repeatability and selectivity. Furthermore, the Au@MOF-303 sensor enables real-time monitoring of breathing signals attached to the surgical mask and the proximity of the fingertips.