Composition-controlled PtCo alloy nanocubes with tuned electrocatalytic activity for oxygen reduction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Improving electrocatalytic oxygen reduction reaction (ORR) activity is crucial for fuel cells.
• Tailoring electronic structure and lattice contraction of platinum (Pt) alloy nanocatalysts is key.
• Controlling nanocatalyst morphology and composition is essential for enhanced ORR performance.

Purpose of the Study:

• To synthesize PtCo alloy nanocubes with controlled compositions (Pt(x)Co NCs).
• To elucidate the effect of nanocatalyst composition on ORR activity.
• To establish the relationship between electronic structure, lattice contraction, and ORR performance.

Main Methods:

• Synthesis of PtCo alloy nanocubes with varying compositions (x=2, 3, 5, 7, 9).
• Electrochemical treatment to form a Pt-skin structure.
• Electrocatalysis experiments, density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) measurements.

Main Results:

• PtCo alloy nanocubes (Pt(x)Co NCs) were successfully synthesized with controlled compositions.
• Pt₃Co NCs exhibited the highest ORR activity among the tested compositions.
• DFT calculations revealed a volcano-type relationship between ORR activity and oxygen binding energy (E(OB)).
• XPS and XRD confirmed that composition tuning altered electronic structure and lattice contraction, correlating with E(OB) changes.

Conclusions:

• Nanocatalyst composition significantly impacts ORR activity.
• Pt₃Co NCs offer optimal E(OB) for maximum ORR activity.
• Controlled composition allows tuning of electronic structure and lattice contraction for enhanced electrocatalysis.