Improved ethanol gas sensing performances of a ZnO/Co3O4 composite induced by its flytrap-like structure.

Nanocomposite materials with excellent receptor and transducer functions are promising in ameliorating their gas sensing properties. However, due to the abrupt changes of receptor and transducer functions when different components are combined together, structural engineering that considers both the receptor and transducer functions to design such desirable sensing materials still remains a great challenge. Here, a nanocomposite material composed of 1D ZnO nanorods and 3D Co3O4 microspheres assembled by single-crystalline porous nanosheets has been designed, which was inspired by the high-efficiency receptor-transducer-response structure of venus flytraps. The as-designed ZnO/Co3O4 composite exhibited high response (Ra/Rg = 125 to 100 ppm ethanol) which was 84 times and 8 times higher than those of Co3O4 (Rg/Ra = 1.43) and ZnO (Ra/Rg = 15). The excellent sensing properties are ascribed to the as-designed flytrap-like structure which possesses a super receptor function from 1D ZnO with a large surface area, p-n heterojunctions with an amplified response signal, as well as excellent transducer functions from single-crystalline porous Co3O4 with fast charge transport channels. This strategy provides us with new guidance on the exploration of high-performance gas sensors which could further extend to other bio-structures that are abundant in nature.