Synthesis of porous nanosheets-assembled ZnO/ZnCo2O4 hierarchical structure for TEA detection

Abstract Hierarchical structures (HSs) of metal oxide semiconductor (MOS) have stimulated tremendous research attentions owing to their fascinating properties. Here, a HS of ZnO/ZnCo2O4 with varied ZnO contents (0–8 wt%) has been successfully prepared via a surfactant-free hydrothermal method combined with subsequent calcination. The prepared ZnO/ZnCo2O4 HS features an ordered assembly of two dimensional (2D) porous nanosheets with the thickness about 15 nm and evenly distributed ZnCo2O4-ZnO p-n junctions. The gas sensing properties of the ZnO/ZnCo2O4 HS were investigated and compared with pure ZnCo2O4 with similar morphology. It was found that after decorating with ZnO, the gas sensing properties of ZnCo2O4 to triethylamine (TEA) were remarkably improved, such as lowered optimum working temperature (decreased from 260 to 220 °C), faster response/recover speed, and higher sensitivity (0.0377/ppm) within a linear concentration range of 5–300 ppm. The improved gas sensing properties can be attributed to the sensitization effect of n-type ZnO on p-type ZnCo2O4 as well as the unique porous nanosheets-assembled hierarchical structure.