α‐Fe ₂2 O ₃3 Polyhedral Nanoparticles Enclosed by Different Crystal Facets: Tunable Synthesis, Formation Mechanism Analysis, and Facets‐dependent nn ‐Butanol Sensing Properties

摘要

> Three kinds of polyhedral α‐Fe ₂ O ₃ nanoparticles enclosed by different facets including oblique parallel hexahedrons (op‐hexahedral NPs), cracked oblique parallel hexahedrons (cop‐hexahedral NPs), and octadecahedral nanoparticles (octadecahedral NPs), were successfully prepared by simply changing only one reaction parameter in the hydrothermal process. The structural and morphological of the products were systematically studied using various characterizations including X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), revealing that the three kinds of α‐Fe ₂ O ₃ nanoparticles were enclosed by {104}, {110}/{104}, and {102}/{012}/{104} crystal planes, respectively. The exposed facets and shape of the nanocrystals were found to be affected by the adding amount of ethylene glycol in the solvent. The gas‐sensing properties and mechanism of the α‐Fe ₂ O ₃ samples were studied and analyzed, which indicated that the sensitivity of the three samples followed the order of octadecahedral NPs cop‐hexahedral NPs op‐hexahedral NPs due to the combined effects of specific surface area and oxygen defects in the nanocrystals.