Tuning the shape and catalytic activity of Fe nanocrystals from rhombic dodecahedra and tetragonal bipyramids to cubes by electrochemistry.

Fe nanocrystal catalysts were synthesized by electrochemistry. Shape transformations of Fe nanocrystals from rhombic dodecahedra and tetragonal bipyramids, both bounded by {110} facets, to 18-facet polyhedra enclosed by different combinations of {110} and {100} facets and finally to cubes exclusively covered by {100} facets have been achieved. A study of the surface-structure functionality of the Fe nanocrystals toward electroreduction of nitrite revealed that the electrocatalytic activity of the Fe nanocrystals increases as the fraction of {100} facets on the surface of the Fe NCs increases.