Origin of achieving the enhanced activity and stability of Pt electrocatalysts with strong metal-support interactions via atomic layer deposition

摘要

The enhancement of catalyst activity and stability by controlling the metal-support interaction is significantly important for the long-term operation of polymer electrolyte membrane fuel cells (PEMFCs). In this work, an extremely stable electrocatalyst of platinum nanoparticles (Pt NPs) immobilized on a carbon support via the bridge layer of nitrogen-doped tantalum oxide (N-Ta2O5) is proposed. The novel N-Ta2O5 bridge layer in between the Pt NPs and carbon surface is synthesized by an atomic layer deposition technique (ALD). It effectively prevents Pt nanocrystals from detachment, migration, and aggregation during the PEMFCs' operation. Electrochemical results indicate that the Pt/N-ALDTa(2)O(5)/C electrocatalyst exhibits superior durability and sufficient catalytic activity for the oxygen reduction reaction, compared to the Pt/C catalyst. X-ray absorption spectroscopy illustrates the strong interactions between the Pt NPs and the N-Ta2O5-decorated carbon support. It is found that the bridge layer of N-Ta2O5 alters the electronic structure of the Pt nanocrystals and contributes to the significantly enhanced catalytic activity and durability for the Pt/ N-ALDTa(2)O(5)/C catalyst. This strategy, by using ALD of N-doped metal oxide to tune the metal-support interface and results in strong metal-support interactions, will benefit the future design of new-generation electrocatalysts with even better activity and longterm durability for PEMFCs application.