Humidity Sensors Based on ZnO-BiFeO3 Nanocomposites

The aim of this study was to investigate the impact of ZnO nanoparticles on the humidity-sensing properties of BiFeO3 nanoparticles. BFO, ZnO, and x% ZnO-BiFeO3 nanoparticles were synthesized using chemical processes and then analyzed by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Raman spectroscopy. The electrical capacitance of the sensors was measured using an impedance meter over a Relative Humidity (RH) range of 17 to 94% at room temperature and at an applied frequency of 100 Hz. This paper demonstrates that adding zinc oxide (ZnO) to bismuth ferrite (BFO) materials significantly improves the humidity response of BFO-based sensors. Indeed, a response of 2.8 × 106% was achieved for 20% ZnO-BFO-based sensors, compared with 5.8 × 103% for a pure BFO-based sensor. At the same time, a low hysteresis effect and excellent long-term stability were observed. In conclusion, the addition of ZnO nanoparticles provides excellent humidity-sensing properties to the BFO material, thereby contributing to its wide range of applications.