Decoupling Electronic Effects in Oxygen Reduction Catalysts via a Model Nanowire Platform

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Understanding electronic structure's role in oxygen reduction reaction (ORR) on platinum (Pt)-based catalysts is challenging due to coupled effects.
• Conventional alloy systems intrinsically link electronic, strain, and ensemble effects, hindering isolated analysis.

Purpose of the Study:

• To decouple electronic effects from structural contributions in Pt-based catalysts for ORR.
• To establish a model platform for rigorously investigating the intrinsic role of electronic structure in ORR activity.

Main Methods:

• Developed a well-defined Pt-based nanowire (NW) model platform.
• Incorporated electron-donating Rhenium (Re) (PtRe) or electron-withdrawing Gold (Au) (PtAu) into Pt NWs.
• Maintained identical morphology, surface structure, and coordination environment to isolate electronic effects.

Main Results:

• Observed a consistent activity trend: PtRe > Pt > PtAu, from intrinsic activity to device performance.
• Established a correlation between electronic structure, intermediate adsorption, and intrinsic ORR activity.
• PtRe NW catalyst demonstrated robust durability with minimal activity decline after extensive cycling.

Conclusions:

• Electron-donating Re enhances Pt's electron density, lowering oxygen intermediate adsorption energy and boosting ORR activity.
• Electron-withdrawing Au has an opposite effect on ORR activity.
• The Pt NW model platform successfully isolates and quantifies the electronic contribution to ORR catalysis.