Size‐controlled Synthesis of Hematite α‐Fe 2 O 3 Nanodisks Closed with (0001) Basal Facets and {11‐20} Side Facets and their Catalytic Performance for CO 2 Hydrogenation

An improved hematite α‐Fe 2 O 3 catalysts composed of uniform nanodisks closed with (0001) basal facets and {11‐20} side facets are prepared via a simple hydrothermal route. Moreover, by simply tuning the mass of the reaction precursors of Fe(NO 3 ) 3 ⋅9H 2 O, the size of the obtained hematite α‐Fe 2 O 3 nanodisks is controlled in the range of 600–100 nm in diameter and 43–230 nm in thickness, respectively. Due to the exposed (0001) basal facets and {11‐20} facets, in which more amount of Fe 3+ ion involved, the obtained α‐Fe 2 O 3 nanodisks exhibit enhanced reducibility. The maximum H 2 consumption occurs at relative lower temperature, ca. 490 °C for the smallest α‐Fe 2 O 3 nanodisks of 43 nm in thickness and 100 nm in diameter, respectively. Relatively, the Fe 3+ ions situated at (0001) planes facilitate the Fischer‐Tropsch synthesis (FTS) compared to that situated at {11‐20} planes. Due to the well dispersion and high fraction of (0001) basal facets, the α‐Fe 2 O 3 nanodisks with middle size of 190 nm in thickness and 400 nm in diameter propose the high CO 2 conversion and high hydrocarbon selectivity. Since more amount of (0001) basal facets are masked by the orientation aggregation along [0001] induced by the self‐magnetization, the least α‐Fe 2 O 3 nanodisks provide a declined catalytic performance for CO 2 hydrogenation.