Subsurface Enrichment of Highly Active Dealloyed Pt-Ni Catalyst Nanoparticles for Oxygen Reduction Reaction

摘要

We present the synthesis of homogenous PtNi and PtNi_3 alloy nanoparticles by organic solution approach, which showed 4-5 fold increases in Pt-mass normalized activity of oxygen reduction reaction (ORR) compared to conventional Pt catalyst after electrochemical dealloying. Using aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy, we found that there is a strong tendency of subsurface enrichment of Ni in the dealloyed Pt-Ni nanoparticles at a higher initial Ni composition (PtNi_3),which therefore resulted in unusual core-shell fine structures. Based on this, a correlation of near-surface compositions to the ORR activities of the dealloyed Pt-Ni catalyst nanoparticles was established.