In-Depth Understanding of the Morphology Effect of α-Fe₂O₃ on Catalytic Ethane Destruction

Shape effects of nanocrystal catalysts in different reactions have attracted remarkable attention. In the present work, three types of α-Fe₂O₃ oxides with different micromorphologies were rationally synthesized via a facile solvothermal method and adopted in deep oxidation of ethane. The physicochemical properties of prepared materials were characterized by XRD, N₂ sorption, FE-SEM, HR-TEM, FTIR, in situ DRIFTS, XPS, Mössbauer spectroscopy, in situ Raman, electron energy loss spectroscopy, and H₂-TPR. Moreover, the formation energy of oxygen vacancy and surface electronic structure on various crystal faces of α-Fe₂O₃ were explored by DFT calculations. It is shown that nanosphere-like α-Fe₂O₃ exhibits much higher ethane destruction activity and reaction stability than nanocube-like α-Fe₂O₃ and nanorod-like α-Fe₂O₃ due to larger amounts of oxygen vacancies and lattice defects, which greatly enhance the concentration of reactive oxygen species, oxygen transfer speed, and material redox property. In addition to this, DFT results reveal that nanosphere-like α-Fe₂O₃ has the lowest formation energy of oxygen vacancy on the (110) facet ( E_vo (110) = 1.97 eV) and the strongest adsorption energy for ethane (-0.26 eV) and O₂ (-1.58 eV), which can accelerate the ethane oxidation process. This study has deepened the understanding of the face-dependent activities of α-Fe₂O₃ in alkane destruction.