Superlattice-Ordered Pt2CoNi Intermetallic Nanocatalysts with Surface Microstrain for Efficient Hydrogen Electrocatalysis
Alloying Pt with non-noble metals optimizes Pt-based electrocatalyst activity, yet random elemental distribution and weak interatomic bonding in disordered alloys limit stability and performance. This study reports a superlattice-ordered Pt2CoNi intermetallic nanocatalyst with abundant surface microstrain for bifunctional hydrogen electrocatalysis. The ordered crystalline structure enforces alternating Pt and Co/Ni atomic arrangements, while multiple Pt2CoNi grains with differing orientations generate microstrain due to intermetallic lattice parameter mismatch. This structure modulates electron distribution, downshifts the d-band center, and accelerates hydrogen adsorption/desorption. The catalyst achieves a hydrogen evolution reaction mass activity of 1.02 A/mg Pt with only 3.7 mV overpotential variation after 10,000 cycles, and a hydrogen oxidation reaction kinetic mass activity of 4.08 A/mg Pt with 97.3% activity retention after 12 h at 0.1 V vs. RHE. These metrics substantially exceed conventional Pt/C benchmarks, addressing the dual challenges of low mass activity and poor durability in proton exchange membrane electrolyzers and fuel cells. The work establishes a rational design route for durable, high-performance intermetallic nanocatalysts via controlled crystal structure engineering.