Dual engineering of helical SnO2 nanostructures and Co2+/Co3+ valence state for ultra-selective acetone detection

초록

Acetone (CH3COCH3) is a key biomarker for non-invasive diagnosis and real-time monitoring of diabetes mellitus, motivating the development of sensing platforms capable of highly sensitive, selective, and humidity-robust detection. Here, we report Co3O4-decorated SnO2 nanohelices (CSNHs) synthesized via sequential glancing-angle deposition (GLAD) as a structurally and electronically engineered framework for high-performance acetone sensing. The optimized 2-nm-thick CSNHs achieve an ultrahigh response of 859.8 to 50 ppm acetone at 350 °C—an 8-fold enhancement over pristine SnO2 nanohelices—along with excellent repeatability (coefficient of variation, CV ≤ 5%) and ultralow theoretical detection limits of 14 ppt (dry) and 175 ppt at 80% relative humidity. Structural analysis and finite element method (FEM) simulations reveal that the helical SnO2 architecture provides extensive inflection points and structural bottlenecks, enabling frequent gas–surface collisions and pronounced modulation of double Schottky barriers. X-ray photoelectron spectroscopy (XPS) analysis confirms that Co3O4 nanoparticle decoration forms p–n heterojunctions and induces interfacial charge transfer, partial Co3+ to Co2+ reduction, and oxygen-vacancy generation, thereby enriching chemisorbed oxygen species and facilitating oxygen spillover onto SnO2. These synergistic structural and catalytic effects collectively endow CSNHs with exceptional acetone sensing capabilities, offering a promising route toward next-generation breath-based diagnostics. © 2026 The Author(s)

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