Metal-organic framework-derived α-Fe2O3 for enhanced acetone gas sensing

Facile strategies for regulating the microstructure and surface chemistry of metal oxide semiconductors are essential for advancing gas sensing technologies. Metal–organic frameworks (MOFs) with well-defined structures serve as ideal sacrificial templates for designing high-performance metal oxide gas sensors. In this work, a series of α-Fe 2 O 3 materials with tunable nanostructures were successfully synthesized via the calcination of NH 2 -MIL-88B(Fe) precursors, where the FeCl 3 /Fe(NO 3 ) 3 molar ratio was systematically varied. The influence of the dual‑iron‑source composition on the morphology, structure, and gas‑sensing properties of the resulting α-Fe 2 O 3 samples (denoted as CN x , x  = 1–5) was systematically investigated. The results demonstrate that the CN3 sensor exhibits a significantly higher response (27.9) to 100 ppm acetone at 260 °C compared to the other samples. Moreover, the CN3 sensor shows a low detection limit, excellent selectivity, satisfactory repeatability, and long-term stability. The enhanced acetone-sensing performance is mainly associated with the synergistic effects of a well-interconnected three-dimensional porous network and abundant oxygen vacancies, which together facilitate gas diffusion, promote oxygen adsorption and surface reactions, and improve the effective utilization of active sites. This study provides a feasible precursor-engineering strategy for fabricating advanced α-Fe 2 O 3 ‑based gas sensors and highlights their potential for non-invasive diabetes monitoring through breath acetone detection.