W-CeO₂ nanospheres gas sensor array for accurate and selective H₂S detection in exhaled breath

Hydrogen sulfide (H₂S), an endogenous gas intricately linked with various physiological disorders, carries paramount importance for medical diagnostics. Despite its significance, rapid and precise H₂S detection in the complex atmosphere of exhaled breath remains a formidable challenge. In this study, W-CeO₂ core@shell nanospheres were synthesized employing a facile one-step hydrothermal method. Particularly, the 7 % W-CeO₂ composite showcased exceptional gas sensing capabilities, characterized by a response of 18.4 and an effective detection threshold of 50 ppb at 225 °C with 80 % RH. The underlying gas-sensing mechanism was meticulously expounded. To enhance the discrimination of sensor responses towards diverse gases, a sensor array encompassing four distinct W-CeO₂ sensors was meticulously devised. By synergizing this sensor array with an algorithmic approach, the discrimination accuracy for qualitative (100 %) and quantitative (89 %) classification of H₂S, ethanol, and their mixtures within a high humidity range. Furthermore, the proposed sensor array's utility was extended to the design of an electronic nose system tailored for H₂S detection in exhaled breath. This platform effectively evaluated its diagnostic efficacy for halitosis, evidencing its capability to discern exhaled breath samples from healthy exhaled samples and simulated halitosis exhaled samples accurately.