Highly sensitive NO2 sensors based on local p-n heterojunctions composed of 0D CuO nanoparticles and 1D ZnO nanorods

A novel and highly sensitive p-n heterojunction sensor composed of zero-dimensional (0D) CuO nanoparticles (NPs) and one-dimensional (1D) ZnO nanorods (NRs) was fabricated using a solution-based process. The structures were characterized with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The formation of electron depletion layers in the p-CuO and n-ZnO is believed to increase the adsorption of NO2, resulting in a 6-fold response improvement and a 13-fold increased sensitivity compared to ZnO NRs alone. We believe that this type of heterojunction device can be applied to many different sensing applications.