Synergistic engineering of shell thickness and core ordering to boost the oxygen reduction performance.

When benchmarked against the extended Pt(111), slightly weaker adsorption and stronger cohesion properties of surface Pt are required to improve activity and durability for the oxygen reduction reaction, respectively, making it challenging to meet both requirements on one surface. Here, using Pt(111) over-layers stressed and modified by Pt-TM (TM = Fe, Co, Ni, V, Cu, Ag, and Pd) intermetallics as examples, we theoretically identified ten promising catalysts by synergistically tailoring the skin thickness and substrate chemical ordering to simultaneously achieve weak adsorption and strong cohesion. More specifically, compared with Pt(111), all candidates exhibit 10-fold enhanced activity, half of which show improved durability, such as mono-layer skin on L1 2 -Pt 3 Co or Pt 3 Fe, double-layer Pt on L1 3 -Pt 3 Ni or Pt 3 Cu, and triple-layer skin on L1 1 -PtCu, while double- or triple-layer skin on L1 0 -PtCo or PtNi and double-layer skin on L1 2 -PtFe 3 show slightly poor durability. Although L1 0 and L1 2 based nanocrystals have been demonstrated extensively as outstanding catalysts, L1 1 and L1 3 ones hold great application potential. The coexistence of high activity and durability on the same surface is because of the different responses of surface adsorption and cohesion properties to the strain effects and ligand effects. When intermetallic-core@Pt-shell nanocrystals are constructed using this slab model, the necessity of protecting or eliminating low-coordinated Pt and the possibility of maximizing Pt(111) facets and core ordering by morphology engineering were highlighted. The current discovery provides a new paradigm toward the rational design of promising cathodic catalysts.