Photochemical Synthesis of Ag Nanoparticles Decorated on ZnO Nanorods for MSM-Structured Humidity Sensors

In this article, we describe the efficient humidity sensors (HR) designed via pure ZnO nanorods (NRDs) and silver (Ag) nanoparticles (NPs)-decorated ZnO NRD grown on the surface of glass substrate by the hydrothermal method during 6 h of the environment at $90~^{\circ }$ C. The physical characteristics of the ZnO NRD and Ag-ZnO NRD were analyzed via field-emission scanning electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The optical properties were analyzed via photoluminescence (PL). In humidity (RH) measurement, the Ag-ZnO NRD displayed high photo-to-dark current ratios (PDCRs), low rise ( ${T} _{\text {r}}$ ), and fall times ( ${T} _{\text {f}}$ ) of 37.5, 9.6 s, and 17.3 s at RH 80% environment. The Ag-ZnO NRD HR exhibited greater results than ZnO HR. The above results indicate that the ZnO NRD decorated with Ag NPs can effectively improve the sensing performance of humidity sensor.