Etching-assisted synthesis of single atom Ni-tailored Pt nanocatalyst enclosed by high-index facets for active and stable oxygen reduction catalysis

Designing structure and compositional distribution are critical for developing high-performance Pt-based oxygen reduction reaction (ORR) catalysts for fuel cells and other metal-air batteries. Here, we report a facile method to simultaneously dope single-atom Ni and expose high-index facets (HIFs) for Pt nanocrystals by chemical etching with HCl. The optimized catalyst displays a mass activity of 2.63 A mgPt−1 and specific activity of 4.15 mA cmPt−2 (0.1 M HClO4), which are both ∼15 times higher than those of commercial 20 wt% Pt/C. Particularly, it shows remarkably enhanced cycling stability. The density functional theory calculations and experimental results demonstrate that the construction of HIFs and single-atom Ni activation in Pt lattice lessen oxygen adsorption energy, which causes enhanced activity. Besides, regulating sub-layer Ni distribution also strengthens the Pt-Pt bonds on the surface, resulting in improved ORR stability.