A comparative study on the acetone sensing properties of ZnO disk pairs, flowers, and walnuts prepared by hydrothermal method

The synthesis of sensing materials in suitable morphology and microstructure is critical for fabricating fast, highly responsive, and reliable acetone sensing devices for human safety and health. Herein, ZnO disk pairs, flower-like, and walnut-like hierarchical architectures were prepared by varying the relative amount of citric acid and NaOH to Zinc acetate dihydrate during the hydrothermal process. At the lowest prime working temperature, the ZnO flowers exhibited the highest gas response, stability, and selectivity towards acetone due to the highest degree of (001) facet exposure and Schottky barrier height, the largest BET specific surface area and BJH average pore size. At the same temperature, the ZnO walnuts displayed the shortest response/recovery time and the lowest limit of detection due to the highest content of surface oxygen vacancy and the high reactivity of adsorbed O-2(-) ions; the ZnO disk pairs showed unique selectivity towards ethylene glycol monomethyl ether due to the highest degree of (100) facet exposure and the smallest BJH average pore size. Replacing Zinc acetate dehydrate by Zinc nitrate hexahydrate improved the acetone sensing performance of the ZnO flowers in terms of response value, stability, and selectivity at the expense of a higher LOD and a slower recovery speed.

Automated summary

The synthesis of sensing materials with suitable morphology and microstructure is crucial for fabricating acetone sensing devices. In this study, different morphologies of ZnO were prepared by adjusting the reactant ratio. The different morphologies exhibited different response performances and selectivity towards acetone.