Guinier–Preston Zones Featuring PtCu Nanocrystals: Coherency Strain Fields Reshaping the Band Structure for Oxygen Reduction Electrocatalysis

Abstract

Microstructurally distorted Pt-based nanoalloys with unusual structural defects like Guinier–Preston (GP) zones with in situ coherency strain fields may be suitable for substantially improving their electrocatalytic performance for the oxygen reduction reaction (ORR) in acidic conditions. Herein, GP zones contributing PtCu nanoalloys were first fabricated by additive manufacturing, starting with the formation of metallic Cu clusters as orderly crystal nuclei on ZIF-8-derived carbon, followed by the additive manufacturing of chemically reduced Pt and Cu on the formed clusters in ethylene glycol at 190 °C. The atomic-scale GP zones give rise to high-level coherent strain fields across the nanocrystals, boosting the ORR kinetics. This catalyst exhibits an ultrahigh oxygen reduction half-wave potential of 0.934 V (vs RHE) and a mass activity (MA) of 0.68 A mg_Pt^–1. After the accelerated degradation test of 50,000 cycles, the achieved MA improved instead of decreasing, rising from 0.68 to 0.89 A mg_Pt^–1, surpassing that of commercial Pt/C significantly. The significantly improved activity is attributed to the coherency strain fields reshaping the band structure and reconstructing a favorable charge density for active Pt sites. Importantly, the interface-anchored GP zones, maintaining a completely coherent relationship with the matrix, can effectively impede metal atom migration, segregation, or leaching, thus enhancing long-term stability. Therefore, the novel GP-type alloys may pave another way for designing advanced catalysts in the realm of current energy storage and conversion fields like fuel cells.