Gradient-Concentration Design of Stable Core-Shell Nanostructure for Acidic Oxygen Reduction Electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Achieving high activity and stability in electrocatalysts is critical for oxygen reduction reactions (ORR) in proton exchange membrane fuel cells.
• Atomic-level control over catalyst surface structure is key to meeting these dual criteria.

Purpose of the Study:

• To develop a durable acidic ORR electrocatalyst with enhanced activity and stability.
• To investigate the structure-property relationships of a novel "defective-armored" Pt-Ni@PtD/G catalyst.

Main Methods:

• Synthesis of Pt-Ni@PtD/G nanoparticles on graphene using galvanic replacement and dealloying.
• Characterization of catalyst structure and composition.
• Electrochemical testing of ORR performance in acidic electrolyte (0.1 m HClO4).

Main Results:

• The Pt-Ni@PtD/G catalyst exhibited a threefold higher mass activity compared to Pt/C for ORR.
• The catalyst demonstrated exceptional stability, retaining 96% of its electrochemically active surface area after 20,000 potential cycles.
• The "defective-armored" structure, featuring a Pt shell over a Pt-Ni core, was responsible for the enhanced performance and durability.

Conclusions:

• The "defective-armored" Pt-Ni@PtD/G catalyst represents a significant advancement in ORR electrocatalyst design for acidic environments.
• The engineered surface structure optimizes electronic properties and provides a protective mechanism against degradation, enabling long-term stability.