A Eu³⁺-decorated α-Fe₂O₃ microflower composite film as a fast-response, low-temperature, and sensitive acetone sensor

This paper reports the preparation of an excellent acetone gas-sensitive material consisting of a Eu³⁺-decorated α-Fe₂O₃ microflower (EFM) composite film by a simple hydrothermal and calcination method. For comparison, pure α-Fe₂O₃ microflowers (PFM) are prepared with the same method. Scanning electron microscopy (SEM) images show that the samples are a loose 3D flower-like structure with many voids surrounded by many thin nanosheets. The structure of the samples was investigated using X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The PFM and EFM gas sensors were systematically tested for gas sensitivity at an optimum temperature of 145 °C. The sensitivity of the EFM gas sensor with 50 ppm of acetone gas was 83, which was up to four times that of the PFM sensitivity (19). The EFM sensor had an extremely fast response time (4 s) and recovery time (38 s). Moreover, the minimum concentration of acetone that we could detect was 0.1 ppm with a response value of 2.1. The enhancement of gas sensitivity was attributed to the high catalytic activity of the Eu³⁺ additive.