Tailored Lattice Compressive Strain of Pt-skins by the L1 2 -Pt 3 M Intermetallic Core for Highly Efficient Oxygen Reduction.

The sluggish kinetics of oxygen reduction reaction (ORR) and unsatisfactory durability of Pt-based catalysts are severely hindering the commercialization of proton exchange membrane fuel cells (PEMFCs). Herein, we tailor the lattice compressive strain of Pt-skins imposed by Pt-based intermetallic cores for highly effective oxygen reduction through the confinement effect of the activated nitrogen-doped porous carbon (a-NPC). The strong confinement effect of modulated pores of a-NPC not only promotes Pt-based intermetallics with ultra-small size (average size < 4 nm), but also efficiently stabilizes intermetallic nanoparticles as well as sufficient exposure of active sites during the ORR process. The optimized catalyst (L1 2 -Pt 3 Co@ML-Pt/NPC 10 ) achieves excellent mass activity (1.72 A mg Pt -1 ) and specific activity (3.49 mA cm Pt -2 ), which are eleven-fold and fifteen-fold that of commercial Pt/C, respectively. Besides, owing to the confinement effect of a-NPC and protection of Pt-skins, L1 2 -Pt 3 Co@ML-Pt/NPC 10 retains 98.1% mass activity after 30,000 cycles, and even 95% for 100,000 cycles, while Pt/C retained only 51.2% for 30,000 cycles. Rationalized by DFT calculation, compared with other metals (Cr, Mn, Fe, Zn), L1 2 -Pt 3 Co closer to the top of "volcano" induces a more suitable compressive strain and electronic structure on Pt-skin, leading to an optimal oxygen adsorption energy and a remarkable ORR performance. This article is protected by copyright. All rights reserved.