Hexagonal α-Fe2O3 nanorods bound by high-index facets as high-performance electrochemical sensor

Hexagonal alpha-Fe2O3 nanorods with high-index facets exposed were synthesized using a double ligand-assisted hydrothermal method (involving PO43- and formamide). The growth process of the synthesized particles obviously proceeded by two stages: (i) formation of capsule-shaped alpha-Fe2O3 nanoparticles along [001] directions and (ii) preferential grow along [112] and/or its equivalent directions to form hexagonal nanorods. The occurrence of this process can be attributed to the stepwise effect of PO43- and formamide. First, the shape of the capsule-shaped alpha-Fe2O3 is mainly regulated by the adsorption of PO43- on those facets parallel to the c-axis of alpha-Fe2O3 during the nanocrystal growth because of the special double coordinated surface hydroxyl on (001) facets, and then the hexagonal structure should result from the preferential growth along [112] and/or its equivalent directions due to the weak adsorption of formamide in the Ostwald ripening process. The as-prepared alpha-Fe2O3 exhibits an excellent electrochemical sensing capability towards H2O2 due to the exposed high-index facets and more active sites of low-coordinated atoms that are located on the edges.