Atomic structure of hematite (α-Fe2O3

Carbon Deposition on Hematite (α-Fe2O3) Nanocubes by Annealing in the Air: Morphology Study with Grazing Incidence Small Angle X-ray Scattering (GISAXS)

“…In a submonolayer of the nanocubes formed on a substrate, the nanocube would adsorb with its faces, not edge nor vertex, contacting with the substrate. Consequently, the top surfaces of all nanocubes are parallel to the substrate and their in-plane orientations are random [10,15]. GISAXS measurements were taken from submonolayer films of the as-prepared, annealed in vacuum and subsequently annealed in the air samples.…”

“…As the air annealing was performed after vacuum annealing, carbon deposition through the air annealing indicates that clean hematite nanocube surfaces interact with CO2 in the air and extract carbon as amorphous form. It might be related to Fe vacancy on the nanocube surface and atomically rough surface after vacuum annealing [15]. It would be interesting to extend current approach to CO2 hydrogenation [37].…”

“…Subtle structural changes of these nanoparticles could be detected relatively easily because shape and size of nanoparticles prior to a reaction are well defined. Especially a pseudo-cubic hematite nanoparticle (hereafter called as nanocube) is enclosed by six crystallographically equivalent {011 ̅ 2} faces [15].…”

Identification of Three Coexistent Defect Types in Hematite Photoanodes through Structure–Property Analysis

“…It is known, for example, that α-Fe 2 O 3 can accommodate ion vacancies in both the iron and oxygen sites, [10,11] and that iron ions can reside in interstitial sites which are expected to be empty. [12,13] Secondary elements can also be intentionally or inadvertently introduced into the lattice, changing the concentration of specific defects and inducing various new types of defects. This strategy has been intentionally pursued using ions such as Si(IV), Sn(IV), or fluoride to tune semiconductor properties and improve PEC performance.…”

“…Their observation relies upon direct observation of unit cell changes, which generally requires high‐quality diffraction studies. [ 13 ] The effect of synthetic protocols and postsynthesis handling has an effect on the identity and concentration of defects present in α‐Fe 2 O 3 . Accurate comparisons of results found across the literature require information regarding these defects, but there currently exists no broadly adopted technique.…”