Dual sulfur-specific pathways in Ag-sensitized Cr2O3 Nanoarchitectures for robust H2S discrimination in complex gas mixtures

초록

Highly selective detection of hydrogen sulfide (H2S) in complex gas mixtures is essential for occupational safety, yet remains challenging due to non-specific redox reactions. In this study, we report highly selective H2S sensors based on Ag-sensitized Cr2O3 nanoarchitectures fabricated via glancing-angle deposition. The superior sensing performance is fundamentally driven by dual sulfur-specific pathways: the AgxO-to-AgxS conversion and the transient sulfidation of the Cr2O3 surface. At an optimal Ag thickness of 3 nm, the sensors exhibit a maximum response of 107.2 to 10 ppm H2S at 300 degrees C, representing a 7.2-fold enhancement over bare Cr2O3. Notably, the sensor maintains strong discrimination against representative interferents (e.g., CH3COCH3, NH3, HCHO, CH4, and CO) and excellent repeatability (coefficient of variation, CV <= 7%) under both dry and 80% RH conditions. Experimental evidence from in-situ Raman and XPS analyses confirms that the sulfur-driven pathways collapse the hole accumulation layer, ensuring an H2S-dominant response even in chemically competitive environments. This work establishes a mechanism-driven design principle for robust H2S discrimination, positioning such nanoengineered architectures as a reliable platform for real-time industrial monitoring and biomedical applications.

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