- By:
- Zhao, Xueru; Chen, Kate; Jiao, Zixian; Zhang, Honghu; Yu, Haoran ; Chen, Xiaobo; Marinkovic, Nebojsa; Lucero, Marcos; Wang, Xiaojing; Zachman, Michael J; Cullen, David A; Liu, Ping; Spendelow, Jacob; Sasaki, Kotaro
- Journal Name:
- Journal of the American Chemical Society
- Page Number:
- 24627-24636
- Volume:
- 148
- Issue Number:
- 24
- Publication Date:
- August 20, 2026
- View DOI Listing:
- https://doi.org/10.1021/jacs.5c21539
Abstract
Gas-driven element redistribution, characterized by the preferential enrichment of one element at the surface relative to the bulk, is frequently observed in multicomponent alloys. Using L10-ordered PtNi as a model system, we reveal that gas pressure plays a critical role in governing adsorption-driven surface composition during annealing in reducing gases: low pressure favors Pt surface segregation, while high pressure facilitates Ni surface enrichment. In this study, we developed a high-pressure nitriding (HPN) strategy that modulates the surface structure and composition of PtNi catalysts. The resulting HPN-PtNi exhibits enhanced performance and durability in membrane electrode assemblies for heavy-duty fuel cell applications, maintaining a high current density of 1.19 A cm–2 at 0.7 V after 90,000 voltage cycles. Through a combination of experimental and theoretical analyses, we reveal that the HPN process forms additional stabilizing Ni–N bonds and induces elemental redistribution with Ni surface enrichment and a Ni-deficient Pt subsurface. These modifications alter the atomic coordination environment of the ordered PtNi phase. This work presents a generalizable strategy to design robust and high-performing Pt-based catalysts by controlling gas-pressure-driven elemental redistribution and dopant incorporation.
