(180n) Extended Pt Alloy Ultrathin Surface As ORR Electrocatalysts

Single crystal surfaces with highly coordinated sites very often hold high specific activities toward oxygen reduction reaction (ORR) and others. However, transferring these high specific activities to practical, high-surface-area electrocatalysts poses significant challenges. In this study, we successfully achieved free-standing extended Pt alloy catalysts by epitaxially depositing Pt alloy on (100)-oriented Cu substrate. The extended Pt alloy surface not only reduces the population of low-coordination sites (e.g., edge and corner atoms prevalent in NPs), but also exhibits 3.1‒6.9% compressive strain. The bulk-like characteristics of extended surface is evidenced by site-probe reactions and various spectroscopic analyses. Notably, its ORR activity exceeds that of bulk Pt₃Ni(100) and Pt(111), showcasing a 19-fold increase in specific activity and a 13-fold increase in mass activity relative to commercial Pt/C. Moreover, the electrochemically active surface area (ECSA) is increased by 4-fold compared to traditional thin films (e.g. NSTF), which makes the catalyst more tolerant to voltage loss at high current densities under fuel cell operation. This study broadens the family of extended surface catalysts and highlights the knowledge-driven approach in the development of advanced electrocatalysts.