An ethanol gas sensor based on lead sulfide (PbS) quantum dots (QDs)-decorated zinc oxide (ZnO) nanorods were demonstrated in this article. The PbS QDs/ZnO film was fabricated via tuning PbS QDs deposition onto the hydrothermally synthesized ZnO nanorods via successive ionic-layer adsorption and reaction (SILAR) method. The PbS QDs/ZnO nanorods nanocomposite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The ethanol gas sensing properties of the PbS QDs/ZnO nanorods-based sensor with different SILAR layers of PbS QDs was investigated at room temperature. The experimental results showed that high response, short response and recovery time, and good repeatability were yielded for the PbS QDs/ZnO nanorods-based sensor, and the optimal SILAR cycle of PbS QDs was discovered to achieve the best ethanol gas sensing performance. The possible sensing mechanism of the PbS QDs/ZnO nanorods-based sensor was attributed to the porous flower-like morphologies, heterojunction nanostructure and high ratio of accessible sites for gas diffusion. (C) 2018 Elsevier Inc. All rights reserved.