Nanoflake assembled hierarchical porous flower-like α-Fe2O3 with large specific surface area for enhanced acetone sensing

High porosity α $\alpha$ -Fe 2 O 3 has attracted a lot of attention due to its exceptional structure. In this paper, nanoflake assembled hierarchical porous flower-like α $\alpha$ -Fe 2 O 3 was prepared by hydrothermal and calcination methods without any additional templates. Scanning electron microscopy (SEM) morphological characterization results show that with the increase of calcination temperature (400 ∘ C, 450 ∘ C, 500 ∘ C, 550 ∘ C, 600 ∘ C), pores appeared. However, the results of nitrogen adsorption show that the specific surface area of the α $\alpha$ -Fe 2 O 3 reaches the maximum value (52.19 $$ m 2 /g) when the calcination temperature is 500 ∘ C. The gas sensing performance of flower-like α $\alpha$ -Fe 2 O 3 with different calcination temperature is compared, interestingly, with the increase of calcination temperature, the response of the samples increased first and then decreased, and reached the maximum value (44.2–100 parts per million (ppm) acetone) when the calcination temperature was 500 ∘ C. The minimum concentration for acetone was 200 ppb (response value is 2.0). Moreover, calcined at 500 ∘ C, hierarchical porous α $\alpha$ -Fe 2 O 3 has a fast response recovery (4/25 s) and low working temperature (210 ∘ C). These excellent gas sensing properties are mainly due to porous structure, large specific surface area, and oxygen vacancies on the surface, which make it a promising material for acetone sensors.