Chemical synthesis of Pt/rare-earth nanoalloys with exclusive ligand effect boosting oxygen electrocatalysis

Abstract

Pt–rare-earth (PtRE) alloys are considered to be highly promising catalysts for oxygen reduction reaction (ORR) in acidic electrolytes. However, the wet-chemical synthesis of PtRE nanoalloys still faces significant challenges. The precise reaction mechanism for ORR of these catalysts is still unclear on significant aspects involving the rate-determining step and the nature of the ligand effect. Herein, we report a class of solvothermal synthesis of PtRE (RE is Dy or La) nanoalloys. Such PtRE nanoalloys here are active and stable in acidic media, with both high mass activities enhanced by 2–5 times relative to commercial Pt/C catalyst and high stabilities indicative of the little activity decay and negligible structure change after 10,000 cycles. Density functional theory calculations firmly confirm that the ligand effect of RE elements accelerates an O–O bond scission and steers the rate-determining steps from OH* + H⁺  + e⁻ → H₂O (on pure Pt surface) to HOOH* + H⁺  + e⁻ → OH* + H₂O (on the PtRE nanoalloy surface) for the fast reaction kinetics, which could be fine-tuned by regulating the RE electronic structures and consequently endows the maximal rate of ORR catalysis with PtDy alloy catalysts.

Graphical abstract