L10-PtCo and L12-Pt3Co Intermetallics for Oxygen Reduction Reaction: The Influence of Composition and Structure on Properties.

Pt-based intermetallics are regarded as highly efficient electrocatalysts for oxygen reduction reaction (ORR). However, Pt-based intermetallics with different Pt: M atomic ratios have different atomic arrangements and crystal structures, which will change the electronic structure and coordination environment of Pt, thus affecting the electrocatalytic activity. In this work, we prepared L1₂-Pt₃Co and L1₀-PtCo intermetallic catalysts by modulating the molar ratio of Pt and Co precursors using a thermal annealing method. The mass activity (MA) of L1₀-PtCo is 0.52 A mg^-1 _Pt at 0.9 V, which is 1.44 times larger than that of L1₂-Pt₃Co (0.36 A mg^-1 _Pt). In addition, the MA of L1₀-PtCo decreases by 17.31 % after 10,000 CV cycles, which is smaller than that of L1₂-Pt₃Co (25.00 % loss in MA), showing excellent structural stability. Theoretical calculations reveal that compared to L1₂-Pt₃Co, L1₀-PtCo has more electrons transferred to the Pt sites, which further optimizes the electronic structure of Pt and reduces the d-band center, leading to the increase of the electrocatalytic performance. This work provides new insights into the study of Pt-based intermetallics with different Pt: M ratios, which is helpful for the screening and preparation of high-performance Pt-based intermetallics.