Hierarchical porous Fe2O3 derived from willow branch slices biotemplate with fast response and excellent selectivity for acetone

Acetone is an important biomarker for clinical diagnosis of diabetes. Therefore, the development of a semiconductor oxide gas sensor with a detection limit below the diagnostic threshold of diabetes (1.8 ppm) is necessary to monitor human health. In this work, hierarchical porous Fe2O3 microtubes with large pore size were prepared by using willow branches as biotemplates. Fe2O3 microtubes (Fe2O3-D2) were obtained by calcining slices of willow branches after soaking in iron nitrate solution for two days, which were assembled from cross-linked nanoparticles in a hierarchical porous structure. Fe2O3-D2 has the largest specific surface area (22.19 m2g−1) compared to Fe2O3-D1 (17.89 m2g−1) and Fe2O3-D3 (10.46 m2g−1), which can provide more reactive sites and facilitate the adsorption of gas molecules on its surface. The Fe2O3-D2-based sensor exhibited high response (16.3) and fast response time (2 s) to 20 ppm acetone at the optimal operating temperature (230 °C). The response of Fe2O3-D2 to 1 ppm acetone is 3.2, which indicates that the detection limit of the sensor is below the threshold of acetone concentration for clinical detection of diabetes. Moreover, the response of the Fe2O3-D2-based sensor to acetone was over 2.7 times higher than that to other test gases such as formaldehyde, toluene, xylene, benzene, methanol, and ethanol, indicating that the sensor has well selectivity for acetone.