Superlattice ordering Pt2CoNi intermetallic nanocatalysts with surface microstrain for efficient hydrogen electrocatalysis

Abstract

Alloying Pt with non-noble metals is effective for optimizing the activity of Pt-based electrocatalysts. However, the development of high-activity and stable hydrogen electrocatalysts remains challenging owing to the random elemental distribution and weak interatomic bonding in alloys. Herein, we reported a Pt₂CoNi intermetallic nanocatalyst rich in surface microstrain for high-performance hydrogen electrocatalysis. The superlattice ordering crystalline structure ensures the specific positions of atoms in this nanocatalyst, resulting in the alternating arrangement of Pt and Co/Ni atoms. In one nanoparticle, multiple Pt₂CoNi grains are arranged along different grain orientations, which generates abundant surface microstrain due to the discrepancy of intermetallic lattice parameters. The unique crystal structure effectively modulates the electron distribution of Pt₂CoNi intermetallic nanocatalyst. The active sites of this nanocatalyst exhibit downshifted d-band centers, leading to accelerated hydrogen adsorption/desorption behavior. Resultantly, the Pt₂CoNi intermetallic nanocatalyst demonstrates impressive bifunctional hydrogen electrocatalytic capabilities for hydrogen evolution reaction (mass activity of 1.02 A/mg_Pt and η₁₀ variation of 3.7 mV after 10,000 cycles) and hydrogen oxidation reaction (kinetic mass activity of 4.08 A/mg_Pt and 97.3% activity retention after 12 h operating at 0.1 V vs. RHE). This work provides a promising route for the development of efficient nanocatalysts with ingenious crystal structures.