PCTS-Controlled Synthesis of L1₀/L1₂-Typed Pt-Mn Intermetallics for Electrocatalytic Oxygen Reduction

Pt-based intermetallics are recognized as effective catalysts for oxygen reduction reaction (ORR) in fuel cells. However, the synthesis of intermetallics often requires prolonged annealing and the effect of different crystal structures on ORR still need to be investigated. Herein, L1(2)-Pt3Mn and L1(0)-PtMn intermetallics with Pt-skin are rapidly synthesized through an emerging periodic carbothermal shock method to investigate their ORR-activity difference. The formation of L1(2)-Pt3Mn and L1(0)-PtMn can be well-controlled by the Pt/Mn feeding ratio, pulse cycles, and temperature. Electrocatalytic investigations show that L1(2)-Pt3Mn presents a more positive half-wave potential (0.91 V vs RHE) and onset potential (1.02 V vs RHE) than those of L1(0)-PtMn. The mass activity and specific activity of L1(2)-Pt3Mn are respectively fourfold and threefold greater than those of L1(0)-PtMn. Theoretical calculations indicate that the L1(2)-Pt3Mn has a more substantial work function than L1(0)-PtMn, thereby conferring L1(2)-Pt3Mn with an increased electron density allocation for catalytic involvement. This electron confinement imparts L1(2)-Pt3Mn with a Pt d-band center lower than that of L1(0)-PtMn, consequently attenuating the adsorption of strongly bonded *O intermediates during the rate-determining step. This study not only employs a straightforward method for intermetallic preparation but also elucidates the discrepancies in ORR activity across intermetallics with distinct structures.