Investigation of a Highly Sensitive Au Nanoparticle-Modified ZnO Nanorod Humidity Sensor

In this article, pure ZnO and Au nanoparticle-modified (ANM) ZnO nanorods (NRs) were well prepared on a glass substrate via the hydrothermal method at 90 °C for 6 h, and the pure ZnO and ANM ZnO NR humidity sensors were fabricated. The crystal and optical properties of the ZnO and ANM ZnO NRs were investigated through scanning electron microscopy (SEM), XRD, photoluminescence (PL), and TEM analyses. The structures of the relative humidity (RH) sensors demonstrated high photo-to-dark current contrast ratios and short response and recovery times during RH measurement. The ANM ZnO NR RH sensor showed better humidity sensing performance than the pure ZnO NR humidity sensor. Under 80% RH, the results of photo-to-dark current contrast ratios, response time, and recovery time were 9.82, 192.44, and 122.42 s, respectively, better than those in pure ZnO NRs RH sensor. These results indicated that humidity sensing property could effectively be improved by Au nanoparticle adsorption.