Sensitivity enhanced and selectivity improved ethanol sensor based on ZnIn2S4 nanosheet-coated In2O3 nanosphere core-shell heterostructure

Constructing core-shell heterostructures can effectively improve the hindered issues such as decreased sensitivity and poor selectivity from the chemoresistive gas sensors in the complex atmosphere. Herein, an effective hydrothermal-water bath treatment combined strategy was designed to obtain the unique ethanol adsorption preferred ZnIn 2 S 4 sheet shell/In 2 O 3 sphere core (ZnIn 2 S 4 @In 2 O 3 ) nanosphere (NS) heterostructures. Particularly, according to the characterization and gas sensing test results, the chemoresistive sensor of ZnIn 2 S 4 @In 2 O 3 NS-2 with the highest chemisorbed oxygen concentration shows satisfactory selectivity to ethanol vapor, and the response is the highest (54) compared to other composite controls, which is almost 4-fold of that of the pure In 2 O 3 NS reference. Besides, the relatively lower working temperature (220 °C), low limit of detection (LOD, 30 ppb) and long-term stability were also obtained. The enhanced performance of the core-shell ZnIn 2 S 4 @In 2 O 3 NS-2 based sensor may be due to the synergistic effect between ZnIn 2 S 4 sheets and In 2 O 3 sphere moieties. Meanwhile, the large specific surface area from the outer shell of ZnIn 2 S 4 sheets is also another contribution factor, which supplies the most chemisorbed oxygen sites and transportation channels to promote the interfacial gas diffusion, catalytic oxidation and product desorption.