A class of PtPb/Pt core/shell nanoplates with large biaxial tensile strain was developed to enhance oxygen reduction reaction (ORR) activity. These nanoplates exhibit high ORR specific and mass activities of 7.8 mA/cm² and 4.3 A/mg Pt at 0.9 V vs. RHE. Density functional theory calculations showed that the edge-Pt and top (bottom)-Pt (110) facets undergo large tensile strains that optimize Pt-O bond strength. The intermetallic core and uniform Pt shell contribute to the high endurance of these catalysts, which can withstand 50,000 voltage cycles with minimal activity decay and no structural or compositional changes. Pt-based catalysts are efficient for fuel cells and industrial reactions but are costly. PtM alloy nanoparticles with a Pt-skin surface are effective for ORR, but their stability is limited. This study demonstrates that large tensile strain on the Pt (110) facet enhances ORR activity. The PtPb/Pt nanoplates show 33.9 and 26.9 times higher ORR activity than commercial Pt/C catalysts. They are also highly active and stable for anodic oxidation reactions, outperforming PtPb nanoparticles and commercial Pt/C. The PtPb/Pt core/shell nanoplates were synthesized using platinum(II) acetylacetonate and lead(II) acetylacetonate as precursors, oleylamine and octadecene as solvents, and ascorbic acid as a reducing agent. The nanoplates have a hexagonal structure with a monodisperse edge length of ~16 nm and a thickness of ~4.5 nm. They are highly crystalline with an intermetallic PtPb phase and a Pt shell with a cubic phase. The nanoplates have a unique Pt (110) surface that is more active for ORR than Pt (111). The PtPb/Pt core/shell structure provides high stability and activity, with the Pt shell preventing the loss of interior transition metals. DFT calculations showed that the tensile strain on the Pt (110) surface enhances ORR activity by optimizing Pt-O bond strength. The PtPb/Pt nanoplates also show high activity and stability for methanol and ethanol oxidation reactions. The study highlights the importance of strain engineering in enhancing catalytic performance.A class of PtPb/Pt core/shell nanoplates with large biaxial tensile strain was developed to enhance oxygen reduction reaction (ORR) activity. These nanoplates exhibit high ORR specific and mass activities of 7.8 mA/cm² and 4.3 A/mg Pt at 0.9 V vs. RHE. Density functional theory calculations showed that the edge-Pt and top (bottom)-Pt (110) facets undergo large tensile strains that optimize Pt-O bond strength. The intermetallic core and uniform Pt shell contribute to the high endurance of these catalysts, which can withstand 50,000 voltage cycles with minimal activity decay and no structural or compositional changes. Pt-based catalysts are efficient for fuel cells and industrial reactions but are costly. PtM alloy nanoparticles with a Pt-skin surface are effective for ORR, but their stability is limited. This study demonstrates that large tensile strain on the Pt (110) facet enhances ORR activity. The PtPb/Pt nanoplates show 33.9 and 26.9 times higher ORR activity than commercial Pt/C catalysts. They are also highly active and stable for anodic oxidation reactions, outperforming PtPb nanoparticles and commercial Pt/C. The PtPb/Pt core/shell nanoplates were synthesized using platinum(II) acetylacetonate and lead(II) acetylacetonate as precursors, oleylamine and octadecene as solvents, and ascorbic acid as a reducing agent. The nanoplates have a hexagonal structure with a monodisperse edge length of ~16 nm and a thickness of ~4.5 nm. They are highly crystalline with an intermetallic PtPb phase and a Pt shell with a cubic phase. The nanoplates have a unique Pt (110) surface that is more active for ORR than Pt (111). The PtPb/Pt core/shell structure provides high stability and activity, with the Pt shell preventing the loss of interior transition metals. DFT calculations showed that the tensile strain on the Pt (110) surface enhances ORR activity by optimizing Pt-O bond strength. The PtPb/Pt nanoplates also show high activity and stability for methanol and ethanol oxidation reactions. The study highlights the importance of strain engineering in enhancing catalytic performance.