The reduction of α-Fe₂O₃ is significant in heterogeneous catalysis. However, due to the changeable crystal phase and the transformation of crystal facet, its reduction mechanism still needs further clarification. In this work, α-Fe₂O₃ rhombohedra, hexagonal-plate and pseudo-cubic with the facets of (1 0 4), (0 0 1) and (1 0 2) respectively were synthesized, and the evolutions of α-Fe₂O₃ structures during H₂ reduction were investigated by multiple means including in-situ XRD. It found that the reduction of α-Fe₂O₃ showed a facet-dependent behavior in H₂ atmosphere, that is different facets exhibited completely different rates and phase transition pathways. Specifically, the Fe₂O₃ (1 0 4) and Fe₃O₄ (2 2 0) had the fastest reduction rate in α-Fe₂O₃ → Fe₃O₄ and Fe₃O₄ → α-Fe, respectively, which was attributed to the higher concentration of oxygen vacancies on the corresponding crystal facets. The phase transition paths for Fe₂O₃ (1 0 2) and Fe₂O₃ (1 0 4) were α-Fe₂O₃ → Fe₃O₄ → α-Fe, while Fe₂O₃ (0 0 1) was α-Fe₂O₃ → Fe₃O₄ → FeO → α-Fe. Additionally, DFT calculations further revealed that Fe₂O₃ (1 0 4) and Fe₃O₄ (2 2 0) had lower interaction energy between O and Fe atoms and easily formed oxygen vacancy. Consequently, these facets presented different formation rates of H₂O, leading to significant differences in the phase transition process.

_{α-Fe 2} O ₃的还原在多相催化中具有重要意义。但由于晶相的变化和晶面的转变，其还原机理仍需进一步阐明。本工作合成了面分别为(1 0 4)、(0 0 1)和(1 0 2)的α-Fe ₂ O ₃菱面体、六方板和赝立方体，并研究了α-Fe 2 O 3 的演化过程。通过包括原位XRD在内的多种手段研究了H ₂还原过程中Fe ₂ O _{3 的}结构。_{结果发现，α-Fe 2} O ₃的还原      _{在H 2}气氛中表现出依赖于面的行为，即不同面表现出完全不同的速率和相变路径。具体而言，Fe ₂ O ₃ (1  0  4)和Fe ₃ O ₄ (2  2 0)分别在α-Fe ₂ O ₃  → Fe ₃ O ₄和Fe ₃ O ₄  → α-Fe 中具有最快的还原率。 ，这归因于相应晶面上氧空位的浓度较高。_{Fe 2} O ₃ (1 0 2) 和 Fe的相变路径  ₂ O ₃ (1  0  4) 为 α-Fe ₂ O ₃  → Fe ₃ O ₄  → α-Fe，而 Fe ₂ O ₃ (0  0  1) 为 α-Fe ₂ O ₃  → Fe ₃ O ₄  → FeO → α-Fe。此外，DFT计算进一步表明，Fe ₂ O ₃ (1  0  4)和Fe ₃ O ₄ (2  2  0)的O和Fe原子之间的相互作用能较低，容易形成氧空位。因此，这些方面呈现出不同的 H _{2形成速率}O，导致相变过程显着差异。