Fully Tensile Strained Pd₃Pb/Pd Tetragonal Nanosheets Enhance Oxygen Reduction Catalysis

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Surface strain engineering is crucial for advanced catalyst design.
• Achieving homogeneous strain distribution in nanostructures is challenging.
• Oxygen reduction reaction (ORR) catalysis requires highly active and stable materials.

Purpose of the Study:

• To develop a new class of core/shell palladium-lead/palladium (Pd-Pb/Pd) nanosheets (NSs) and nanocubes (NCs).
• To engineer homogeneous tensile strain in Pd shells for enhanced ORR performance.
• To investigate the catalytic mechanism and stability of the novel nanostructures.

Main Methods:

• Synthesis of Pd-Pb/Pd core/shell NSs and NCs.
• Electrochemical characterization of ORR activity and stability.
• Valence band photoemission spectroscopy.
• First-principles calculations.

Main Results:

• Pd-Pb/Pd NSs and NCs exhibited significantly increased mass and specific activities for ORR compared to unshelled structures.
• Pd3Pb/Pd NSs demonstrated 8.8-9.4 times higher ORR activity than commercial Pd/C and Pt/C.
• Tensile strained Pd shells upshifted the d-band center, weakening oxygenated species chemisorption.
• The catalysts showed excellent stability over 20,000 potential cycles.

Conclusions:

• Homogeneous tensile strain in Pd-Pb/Pd nanostructures effectively boosts ORR catalysis.
• The d-band center shift is key to the enhanced catalytic activity.
• These core/shell nanostructures offer a promising pathway for designing highly active and stable fuel cell catalysts.