Construction of 0D guanine nanospheres/2D vermiculite nanosheets heterostructures in confined space towards humidity sensing and proton migrations

Heterostructures comprising zero–dimensional (0D) nanoparticles and two–dimensional (2D) nanosheets have garnered considerable interest for sensing applications. Guanine exhibits extraordinary functionality in terms of their abundant hydrogen bond donors/acceptors. In this study, the protonated amine matrix of guanine serves as augmented active sites, uniformly forming guanine nanoparticles (GN) between 2D vermiculite nanosheets (VMT) confined space. Through electrostatic interactions and cross–linking with heptanedioic acid (HA), a self–assembly heterostructure (GN/VMT–HA) was constructed, which may offer abundant transport channels for enhanced humidity sensing and proton migrations. The proton migrations of GN/VMT–HA increased from 0.585 mS/cm (11% RH) to 0.750 mS/cm (97%RH) at 25 °C. The humidity sensor based on GN/VMT–HA demonstrates excellent performance, including high sensitivity (30.20 Hz/%RH), small hysteresis (1.45% RH) and short response/recovery time (25 s/7 s). This study offers a simple green method for constructing 0D/2D nanocomposites for proton transfer and humidity–sensing applications.