Humidity sensing properties of nanocrystalline ZnWO4 with porous structures

Nanocrystalline zinc tungstate (ZnWO4) with different morphologies (nanoparticles, nanorods) was prepared via precipitation or hydrothermal method. The structures and morphologies of ZnWO4 were characterized and the results manifested that as-prepared products had wide range pore size distribution from 1 nm to 160 nm. Thick film sensing devices using the as-prepared ZnWO4 were fabricated and evaluated for humidity sensing properties including frequencies, humidity hysteresis, response and recovery at room temperature. These results manifest the potential application of ZnWO4 nanorods for fabricating high performance humidity sensor. The morphologies of nanocrystalline ZnWO4 have a significant influence on the humidity sensing properties, including response and recovery kinetics as well as humidity hysteresis. The possible humidity sensing mechanism and reasons for leading to the different sensing performance of the ZnWO4 samples were discussed.