Model Metallic Glasses for Superior Electrocatalytic Performance in a Hydrogen Oxidation Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Metallic glasses (amorphous alloys) offer excellent stability and nanostructuring capabilities for electrocatalysis.
• Their potential in proton-exchange membrane fuel cells is promising, but alloy chemistry's role in catalytic activity is not well understood.

Purpose of the Study:

• To investigate how alloy chemistry and electronic structure influence hydrogen oxidation reaction (HOR) activity in Pt-Pd-Cu-Ni-P bulk metallic glasses (BMGs).

Main Methods:

• Systematic synthesis of Pt-Pd-Cu-Ni-P BMGs with varying Pt and Pd content (x = 0 to 42.5 at%).
• Electrochemical evaluation of HOR activity and electrochemical active surface area.
• Analysis of electronic structure using core level binding energies and electron work function.
• Density functional theory (DFT) calculations to model hydrogen adsorption and reaction energetics.

Main Results:

• HOR activity and surface area showed volcano-shaped plots, peaking at an equal Pt:Pd ratio.
• Optimized compositions exhibited reduced charge-transfer resistance and improved activity, attributed to lower electron work function and higher Pt core level binding energy.
• DFT calculations confirmed lower free energy change and higher hydrogen adsorption density for optimal BMG compositions, indicating synergistic effects between Pt and Pd.

Conclusions:

• Alloy chemistry significantly impacts the electronic structure and HOR electrocatalytic activity of Pt-Pd-Cu-Ni-P BMGs.
• A synergistic effect between Pt and Pd in BMGs enhances hydrogen oxidation reaction performance in fuel cells.