Preparation of porous Co3O4-ZnO nanosheet composites and study of their gas-sensitive properties

Herein, a novel Co3O4/ZnO heterostructured composite was successfully fabricated using a facile one-pot method in combination with subsequent heat treatment, which showed excellent performance in detecting n-butanol. The crystal structure, micromorphology, pore structure, molecular structure, and surface elemental valence structure of the composite were subjected to systematic characterization including XRD, TEM, SEM, BET, and XPS techniques. It was demonstrated that Co3O4/ZnO composite mainly existed in the form of mesoporous pores with an average pore size of 46.64 nm. While applied in gas sensing experiments, all sensors tended to increase at 280 °C and then decreased as the temperature continued to rise. Furthermore, at each working temperature, the response values of Co3O4/ZnO sensors outweighed that of pure ZnO sensors, with Co3O4/ZnO-2 sensor (108) six times greater than pure ZnO (18). The response recovery time also exhibited a 25 s and 10 s improvement, respectively. Eventually, the behind gas sensitivity mechanism of Co3O4/ZnO sensor was explored and the formation of heterojunctions and bigger pore sizes in composites was proved to be key contributors to the improved gas sensitivity.