Trimetallic Pt–Pd–Ni octahedral nanocages with subnanometer thick-wall towards high oxygen reduction reaction

Precisely engineering the composition and structure of nanomaterials can effectively tune their activity and stability towards oxygen reduction reaction (ORR), a key process in fuel cells. Here, a highly active and stable electrocatalyst for ORR is fabricated by alloying Ni atoms with octahedral Pt–Pd nanocages with ultrathin walls and exposed (111) facets. The specific activity (3.8 mA/cm2) and mass activity (1.17 A/mgPt) of the octahedral Pt–Pd–Ni nanocages represent a performance enhancement by a factor of 25 and 10 compared to commercial Pt/C, respectively. In addition, the ORR activity of octahedral Pt–Pd–Ni nanocages significantly outperforms the octahedral Pt–Pd nanocages (1.89 mA/cm2 and 0.73 A/mgPt in specific and mass activity). The ligand effect and compressive strain, confirmed by the X-ray absorption fine structure (XAFS) analysis and density functional theory (DFT) calculations, accounts for the enhanced activity by weakening the adsorption energy of hydroxyl groups. Particularly, it shows robust stability with only 16% decay in the mass activity after accelerating degradation tests (ADTs), rationalized by its structural stability and high vacancy formation energy. This work provides a new class of Pt based nanocatalysts with high activity and stability for ORR. Trimetallic Pt–Pd–Ni octahedral nanocages with ultrathin wall for oxygen reduction reaction are synthesized. This material shows superior mass and specific activity (1.17 A/mgPt and 3.8 mA/cm2) and robust stability for ORR. The compressive strain effect and high vacancy formation energy accounts for the high activity and stability of the trimetallic Pt–Pd–Ni octahedral nanocages. [Display omitted] •Trimetallic octahedral Pt–Pd–Ni nanocages were firstly synthesized as electrocatalysts for oxygen reduction reaction.•The mass activity of the Pt–Pd–Ni octahedral nanocages at 0.9 V achieved a factor of 10 enhancement compared to commercial Pt/C.•The Pt–Pd–Ni nanocages showed a greatly enhanced stability.•The enhanced mechanism on the Pt-Pd-Ni octahedral nanocages have been investigated by the combination of advanced XAS spectrum and DFT calculation.