Monodisperse Y-type CoO hierarchical nanostructure/reduced graphene oxide for improved NO2 detection at room temperature with enhanced moisture resistance

The fabrication of high-performance gas-sensitive materials with enhanced moisture resistance is an important research topic. In this work, monodisperse Y-type CoO hierarchical nanostructures with a branch length of about 16 nm have been prepared, and then uniformly dispersed on the surface of reduced oxide graphene (rGO) by hot injection method. The composite exhibited a rapid response to NO 2 at room temperature. The optimal response was about 40–100 ppm NO 2 , the response time was 620 s to 10 ppm NO 2 and the detection limit was 0.01 ppm. It was due to the combination of more NO 2 adsorption active sites of Y-type CoO and faster carrier transfer of rGO. Even at high relative humidity (RH) conditions of 80%, the sensor still retained a high response value of about 90% of that measured at the normal RH (25%). The effective wrapping of stearate ligands inhibited the entrance of water vapor molecules, which could effectively improve the hydrophobic properties of the composite and resulted in enhanced moisture resistance. It may provide a new path for improved NO 2 detection with enhanced moisture resistance at room temperature.