Symmetry-induced Regulation of Pt Strain Derived from Pt 3 Ga Intermetallic for Boosting Oxygen Reduction Reaction.

Pt-based fuel cell catalysts with excellent activity and stability for proton-exchange membrane fuel cells (PEMFCs) have been developed through strain regulation in recent years. Herein, we demonstrated that symmetry-induced strain regulation of Pt surface of PtGa intermetallic compounds can greatly enhance the catalytic performance of the oxygen reduction reaction (ORR). With the strain environment varies derived from the lattice mismatch of analogous PtGa core but different symmetry, the Pt surface of the PtGa alloy and the Pt 3 Ga (Pm 3 ¯ $\bar{3}$ m) precisely realized 0.58% and 2.7% compressive strain compared to the Pt 3 Ga (P4/mmm. Experimental and theoretical results reveal that when the compressive stress of the Pt lattice increases, the desorption process of O* intermediates becomes accelerated, which is conducive to oxygen reduction. The Pt 3 Ga (Pm 3 ¯ $\bar{3}$ m) with high symmetry and compressive Pt surface exhibited the highest mass and specific activities of 2.18 A⋅mg Pt -1 and 5.36 mA⋅cm -2 , respectively, which were more than one order of magnitude higher than those of commercial Pt/C catalysts. We demonstrated that material symmetry can be used to precisely modulate Pt surface stress to enhance the oxygen reduction reaction, as well as provide a distinct platform to investigate the relationship between Pt compressibility and catalytic activity. This article is protected by copyright. All rights reserved.