Size-controlled Synthesis of Hematite alpha-Fe2O3 Nanodisks Closed with (0001) Basal Facets and {11-20} Side Facets and their Catalytic Performance for CO2 Hydrogenation

An improved hematite alpha-Fe2O3 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(NO3)(3)9H(2)O, the size of the obtained hematite alpha-Fe2O3 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 Fe3+ ion involved, the obtained alpha-Fe2O3 nanodisks exhibit enhanced reducibility. The maximum H-2 consumption occurs at relative lower temperature, ca. 490 degrees C for the smallest alpha-Fe2O3 nanodisks of 43 nm in thickness and 100 nm in diameter, respectively. Relatively, the Fe3+ 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 alpha-Fe2O3 nanodisks with middle size of 190 nm in thickness and 400 nm in diameter propose the high CO2 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 alpha-Fe2O3 nanodisks provide a declined catalytic performance for CO2 hydrogenation.