3D flower-like Co3O4@ZnO nanostructures for trace-level acetone detection at low operating temperatures

초록

Enhancing p-type metal oxide semiconductors (MOS) sensitivity at low temperatures is critical for detecting acetone, a toxic pollutant and diabetes biomarker. This study presents a 3D flower-like Co3O4@ZnO composite synthesized via additive-free hydrothermal method combined with inert gas calcination. The inert gas environment minimizes oxidation and oxygen interference, forming a robust nanoneedle-based hierarchical structure with high integrity, a large surface area (52.13 m(2)g(-1)), and uniform mesopores (similar to 10 nm) to facilitate efficient gas diffusion and reactions. The ZnO-Co3O4 heterojunction enhances band-bending modulation and refines carrier dynamics by synergizing ZnO's exceptional carrier mobility with Co3O4's robust redox catalytic activity, delivering markedly improved sensing performance. The optimized composite (CZ-3, Co3O4:ZnO = 0.5:0.5) demonstrated exceptional acetone sensing performance, achieving a 35.85% response to 100 ppm acetone at 150 degrees C, rapid response/recovery times of 40/28 s, a linear detection range of 1-150 ppm, and an ultra-low detection limit of 100 ppb. The sensor also exhibited a measurable response (0.35 %) to human exhaled breath, demonstrating its potential for non-invasive healthcare diagnostics. In contrast, the lower ZnO content in Co3O4 (CZ-1) sensor showed reduced performance, responding to 500 ppb acetone with a response of 29% to 100 ppm. These results emphasize the critical role of the heterojunction with an optimized balance of p- and n-MOS in enhancing sensing performance, highlighting a sustainable and scalable approach for advancing high-performance p-type MOS gas sensors. The proposed composite demonstrates significant potential for precise, low-temperature acetone detection in environmental monitoring and non-invasive healthcare diagnostics.

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