Phase-transfer interface promoted corrosion from PtNi₁₀ nanoctahedra to Pt₄Ni nanoframes

A novel two-phase approach towards the corrosion of PtNi₁₀ nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNi₁₀ nanoctahedra which resided in the upper toluene phase, suffered from etching and was then transferred into a lower aqueous phase with coordination by ethylenediaminetetraacetate (EDTA). Due to the existence of the phase-transfer interface promoted by EDTA, the corrosion reaction proceeded at an accelerated rate under the mild conditions. Specifically, the resultant products of octahedral Pt₄Ni nanoframes were successfully fabricated for the first time, and PtNi₄ porous octahedra could be obtained when the dosage of EDTA-2Na was reduced. After a systematic study of this two-phase system, a "synergetic corrosion" mechanism is proposed to account for the formation of octahedral Pt₄Ni nanoframes, involving contributions from many species (i.e., O₂, H₂O, H⁺, OAm, and EDTA^4-). As a result of the fascinating three-dimensional geometry of Pt₄Ni nanoframes and PtNi₄ porous octahedra, both of the corroded nanocrystals showed superior activity over the pristine PtNi₁₀ nanoctahedra for ethanol electrooxidation in alkaline media and hydrogenation of nitrobenzene.