Biphase Pd Nanosheets with Atomic-Hybrid RhO x /Pd Amorphous Skins Disentangle the Activity-Stability Trade-Off in Oxygen Reduction Reaction.

The activity-stability trade-off relationship of oxygen reduction reaction (ORR) is a tricky issue that strikes the electrocatalyst population and hinders the widespread application of fuel cells. Here we develop neoteric biphase Pd nanosheets that are structured with ultrathin 2D crystalline Pd inner cores and ∼1 nm-thin atomic-hybrid RhO x /Pd amorphous skins, named c/a-Pd@PdRh NSs, for disentangling this trade-off dilemma for alkaline ORR. The superthin amorphous skins significantly amplify the quantity of flexibly low-coordinated atoms for electrocatalysis. An in-situ selected oxidation of the top-surface Rh dopants creates atomically hybrid RhO x /Pd disorder surfaces. Detailed energy spectra and theoretical simulation confirm that these RhO x /Pd interfaces can arouse a surface charge redistribution, causing significant electron deficiency and lowered d-band center for surface Pd. Meanwhile, anti-corrosive Rh/RhO x species can thermodynamically passivate the neighboring Pd atoms from oxidative dissolution. Thanks to these amplified interfacial effects, the biphase c/a-Pd@PdRh NSs simultaneously exhibit a superhigh ORR activity (5.92 A mg -1 , 22.8 times that of Pt/C) and an outstanding long-lasting stability after 100k cycles of accelerated durability test, showcasing unprecedented electrocatalysts for breaking the activity-stability trade-off relationship of ORR. This work paves a bran-new strategy for designing high-performance electrocatalysts through creating modulated amorphous skins on low-dimensional nanomaterials. This article is protected by copyright. All rights reserved.