Ultrafine\nPt<sub>3</sub>Fe Intermetallic Electrocatalysts\nFormed by Ultrafast Joule Heating toward Ethanol Oxidation

Ordered intermetallic nanocrystals display great potential\nfor\nfuel cells due to their distinctive electronic and structural properties.\nHowever, the traditional synthesis usually involves long-time annealing\nat high temperature or surfactant/reductant with antiaggregation property,\nleading to decreased electrocatalytic performance. Herein, an ultrafast\nand surfactant-free synthesis of ordered sub–5-nm Pt<sub>3</sub>Fe nanocrystal-based electrocatalysts was reported (O–Pt<sub>3</sub>Fe/rGO). Through Joule heating, Pt<sub>3</sub>Fe nanocrystals\nwere formed <i>in situ</i> on reduced graphene oxide within\ndozens of seconds. The modulation of the ordered or disordered structure\nof the Pt<sub>3</sub>Fe alloys could also be achieved by the simple\nadjustment of experimental parameters. O–Pt<sub>3</sub>Fe/rGO\nwith a unique structure shows a superior mass activity of 5.66 A mg<sup>–1</sup> toward ethanol oxidation reactions (EOR), which is\n7.1 and 2.5 times higher than the values of the benchmark Pt/C and\nthe counterpart catalysts containing disordered Pt<sub>3</sub>Fe nanoalloys\n(D-Pt<sub>3</sub>Fe/rGO). O–Pt<sub>3</sub>Fe/rGO also demonstrates\nsuperb long-term stability, retaining ∼80.7% of its original\nmass activity after electrochemical aging. Density functional theory\n(DFT) calculations reveal that the catalysts with ordered Pt<sub>3</sub>Fe show downshifted d-band center, weakened CO adsorption, enhanced\nOH adsorption, and improved C–C cleavage capability compared\nwith the one with disordered Pt<sub>3</sub>Fe. This study provides\na new perspective for the efficient synthesis of highly ordered intermetallic\ncompound catalysts for energy conversion.