Ultrafine Pt₃Fe Intermetallic Electrocatalysts Formed by Ultrafast Joule Heating toward Ethanol Oxidation

Ordered intermetallic nanocrystals display great potential for fuel cells due to their distinctive electronic and structural properties. However, the traditional synthesis usually involves long-time annealing at high temperature or surfactant/reductant with antiaggregation property, leading to decreased electrocatalytic performance. Herein, an ultrafast and surfactant-free synthesis of ordered sub-5-nm Pt₃Fe nanocrystal-based electrocatalysts was reported (O-Pt₃Fe/rGO). Through Joule heating, Pt₃Fe nanocrystals were formed in situ on reduced graphene oxide within dozens of seconds. The modulation of the ordered or disordered structure of the Pt₃Fe alloys could also be achieved by the simple adjustment of experimental parameters. O-Pt₃Fe/rGO with a unique structure shows a superior mass activity of 5.66 A mg^-1 toward ethanol oxidation reactions (EOR), which is 7.1 and 2.5 times higher than the values of the benchmark Pt/C and the counterpart catalysts containing disordered Pt₃Fe nanoalloys (D-Pt₃Fe/rGO). O-Pt₃Fe/rGO also demonstrates superb long-term stability, retaining ∼80.7% of its original mass activity after electrochemical aging. Density functional theory (DFT) calculations reveal that the catalysts with ordered Pt₃Fe show downshifted d-band center, weakened CO adsorption, enhanced OH adsorption, and improved C-C cleavage capability compared with the one with disordered Pt₃Fe. This study provides a new perspective for the efficient synthesis of highly ordered intermetallic compound catalysts for energy conversion.