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

Abstract

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 ZnIn2S4 sheet shell/In2O3 sphere core (ZnIn2S4 @In2O3) nanosphere (NS) heterostructures. Particularly, according to the characterization and gas sensing test results, the chemoresistive sensor of ZnIn2S4 @In2O3 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 In2O3 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 ZnIn2S4 @In2O3 NS-2 based sensor may be due to the synergistic effect between ZnIn2S4 sheets and In2O3 sphere moieties. Meanwhile, the large specific surface area from the outer shell of ZnIn2S4 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.