Research progress in β-Fe2O3-based catalysts: An overview of the synthesis, conversion and applications

Fe2O3, as a substance that exists in nature in large quantities, has been widely paid close attention by many scholars because of its excellent properties. Fe2O3 can be divided into four phases depending on the crystal structure. As a narrow band gap semiconductor, beta-Fe2O3 has a band gap of about 1.77-1.83 eV, which is much lower than the average band gap of Fe2O3 (2.1 eV), and its theoretical saturated photocurrent density is 35% higher than that of alpha-Fe2O3, showing excellent light absorption characteristics and water oxidation capacity, which is a promising photoanode material. As the only polycrystalline phase of iron oxide that exhibits paramagnetism at room temperature, it also has a very bright prospect in the field of magnetic resonance. This paper focuses on the review of rare phase beta-Fe2O3. Firstly, the crystal structure, magnetism of beta-Fe2O3 and the mature methods for preparing pure beta-Fe2O3 are summarized. Secondly, the conversion relationships between beta phase and other phases of Fe2O3 is reviewed, and the important factors affecting this process are summarized. As for the improvement and applications, it points out a variety of improvement methods such as heterojunction, element doping and morphology control, and discusses the applications of beta-Fe2O3 in many fields such as photocatalysis, Fenton oxidation, photochemical hydrogen production, biomedicine and toxic gas detection. Finally, the application prospect and challenges of beta-Fe2O3 are prospected. This paper aims to further demonstrate the latent capacity of beta-Fe2O3. It also provides ideas for the application of this substance in other environmental remediation fields.