Kinetics-Driven\nCrystal Facet Evolution Mechanism\nof Atomically Ordered Intermetallic PtFe Nanocubes toward Electrochemical\nCatalysis

Crystal structure engineering in nanoparticles has been\nregarded\nas a vital method in catalyst development and design. Herein, PtFe\nnanocubes, manufactured with ordered PtFe intermetallic structure\nand a desired facet of {202}, have been successfully prepared via\nthe combination of selective deposition strategy and spatial barrier\neffect. In-situ X-ray photoelectron spectroscopy found that the growth\nof the high-index facet and formation of the nanocube for o-PtFe-202\nmaterials arise from the surface Fe<sup>2+</sup> modification stabilized\neffect and the selective deposition of Cl<sup>–</sup>, respectively.\nMoreover, density functional theory calculations and X-ray adsorption\nspectroscopies further proved that the improved oxygen reduction reaction\nactivity and stability of o-PtFe-202 mainly originate from the synergistic\neffect of the desired high-index facet, ordered crystal structure,\nand resulting optimal d-band center of Pt. As expected, the o-PtFe-202\nexhibits excellent mass activity (2.48 mA·ug<sub>Pt</sub><sup>–1</sup>) and specific activity (7.78 mA·cm<sup>–2</sup>), with only a 7.3% decrease in mass activity after 30 000\ncycles.