Indexed by: Research Article

First Author: Liu,Xuan

Correspondence Author: Li,Qing

Co-author: Elbaz,Lior,Huang,Yunhui,Cai,Zhao,Su,Dong,Zhang,Siyang,Li,Shenzhou,Liang,Jiashun,Wang,Yuhan

Journal: Journal of the American Chemical Society

Affiliation of Author(s): 华中科技大学

Place of Publication: 美国

Document Type: Article

Volume: 146

Issue: 3

Page Number: 2033-2042

ISSN No.: 0002-7863

Key Words: Catalysts; Lattices; Platinum; Polarization; Redox reactions

DOI number: 10.1021/jacs.3c10681

Date of Publication: 2024-01-11

Impact Factor: 14.4

Abstract: Surface polarization under harsh electrochemical environments usually puts catalysts in a thermodynamically unstable state, which strictly hampers the thermodynamic stability of Pt-based catalysts in high-performance fuel cells. Here, we report a strategy by introducing electron buffers (variable-valence metals, M = Ti, V, Cr, and Nb) into intermetallic Pt alloy nanoparticle catalysts to suppress the surface polarization of Pt shells using the structurally ordered L10-M-PtFe as a proof of concept. Operando X-ray absorption spectra analysis suggests that with the potential increase, electron buffers, especially Cr, could facilitate an electron flow to form a electron-enriched Pt shell and thus weaken the surface polarization and tensile Pt strain. The best-performing L10-Cr-PtFe/C catalyst delivers superb oxygen reduction reaction (ORR) activity (mass activity = 1.41/1.02 A mgPt–1 at 0.9 V, rated power density = 14.0/9.2 W mgPt–1 in H2-air under a total Pt loading of 0.075/0.125 mgPt cm–2, respectively) and stability (20 mV voltage loss at 0.8 A cm–2 after 60,000 cycles of accelerated durability test) in a fuel cell cathode, representing one of the best reported ORR catalysts. Density functional theory calculations reveal that the optimized surface strain by introducing Cr on L10-PtFe/C accounts for the enhanced ORR activity, and the durability enhancement stems from the charge transfer contribution of Cr to the Pt shells and the increased kinetic energy barrier for Pt dissolution/Fe diffusion.