α‐Fe₂O₃ Polyhedral Nanoparticles Enclosed by Different Crystal Facets: Tunable Synthesis, Formation Mechanism Analysis, and Facets‐dependent n‐Butanol Sensing Properties

Abstract

Three kinds of polyhedral α‐Fe2O3 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‐Fe2O3 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‐Fe2O3 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.

In situ construction of N-doped Ti3C2T x confined worm-like Fe2O3 nanoparticles by Fe–O–Ti bonding for LIBs anode with superior cycle performance

“…Transition metal oxides (TMOs) [5], such as Fe 2 O 3 [6][7][8][9], Fe 3 O 4 [10], TiO 2 [11], and Co 3 O 4 [7], have much higher theoretical specific capacity than graphite by conversion reaction mechanisms (M x O y + 2yLi + + 2ye − = XM0 + yLi 0 ) [12], which are considered as potential candidate materials for LIBs anode. Among all kinds of TMOs, Fe 2 O 3 has drawn considerable attention, owing to its high theoretical capacity (1007 mAh g −1 ), non-toxicity, high natural abundance, low cost, etc [13,14]. However, its poor electrical conductivity and obvious volume change during the charge/discharge process would result in rapid capacity decay [15].…”

Crystal facet effect of tin dioxide nanocrystals on photocatalytic degradation and photo-assisted gas sensing properties

“…17 In the field of gas sensing, it has been also shown that the crystal facets of metal oxide nanomaterials with higher surface energy often had more dangling bonds and could introduce more effective adsorption sites for target gases, which resulted in better gas sensing activities. 18 Such crystal facet dependent gas sensing properties have been reported in a variety of metal oxide gas sensing materials, including SnO 2 , 19 ZnO, 20 TiO 2 , 21,22 Fe 2 O 3 , 23 Cu 2 O, 24 and NiO. 25 In short, engineering the crystal facets of nanomaterials not only leads to fine-tuning of the performance at the atomic and electronic levels, but also provides a good opportunity for the in-depth study of the related performance mechanism.…”