Tuning Electronic Structure and Lattice Diffusion Barrier of Ternary Pt–In–Ni for Both Improved Activity and Stability Properties in Oxygen Reduction Electrocatalysis

Abstract

Pt-based alloy electrocatalysts with both good oxygen reduction reaction (ORR) activity and stability have been widely recognized as the key points to realize the fuel cell economy, which however has remained a challenge in the research field. Here, we report an achievement of both improved ORR activity and catalyst stability by incorporating post-transition-metal indium into Pt–Ni alloy nanoparticles. Theoretical simulations suggest the introduction of indium would effectively increase the lattice atom diffusion energy barrier and decrease the particle surface energy, which help with improving the structural stability by decelerating internal Ni leaching and stabilizing the active surface. In the meantime, the electronic structure and consequently ORR activity property of this ternary alloy catalyst would be tuned by controlling its particle composition. Ternary Pt–In–Ni alloy catalysts with controlled particle compositions are synthesized and studied for the ORR properties, which show good agreement with the theoretical study. The Pt₂In_0.2Ni_1.8 nanoparticles with the optimal composition exhibit an initial mass activity of 0.76 A mg_Pt^–1 and retain ～97.5% of initial activity after accelerated stress test.