Mixture Phases Engineering of PtFe Nanofoams for Efficient Hydrogen Evolution.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Phase engineering is crucial for developing efficient platinum-iron (PtFe) catalysts for the hydrogen evolution reaction (HER).
• Achieving optimal phase control in PtFe catalysts remains a significant challenge for maximizing HER performance.

Purpose of the Study:

• To synthesize PtFe nanofoams with distinct phases (face-centered cubic (fcc), simple cubic crystalline (scc), and a mixture (PtFe-mix)) using hydrogen-assisted calcination.
• To evaluate and compare the HER activity and stability of the synthesized PtFe phases.
• To elucidate the underlying mechanisms contributing to the enhanced HER performance of the PtFe-mix catalyst.

Main Methods:

• Hydrogen-assisted calcination for synthesizing PtFe nanofoams with controlled phases.
• Electrochemical characterization, including overpotential measurements at 10 mA cm⁻², to benchmark HER activity.
• Long-term stability testing of the catalysts.
• Density functional theory (DFT) calculations to investigate electronic structure and reaction pathways.

Main Results:

• Successful synthesis of PtFe nanofoams in fcc, scc, and PtFe-mix phases.
• PtFe-mix exhibited excellent HER activity in 1.0 M KOH, with an overpotential of 28 mV to reach 10 mA cm⁻², surpassing commercial Pt/C (34 mV).
• PtFe-mix demonstrated remarkable stability over 24 hours.
• DFT calculations confirmed a more favorable d-band center and lower energy barrier for water dissociation in PtFe-mix, facilitating HER.

Conclusions:

• Hydrogen-assisted calcination is an effective method for phase engineering of PtFe catalysts.
• The PtFe-mix phase offers superior HER activity and stability compared to single-phase PtFe and commercial Pt/C.
• The enhanced performance is attributed to optimized electronic structure and improved water dissociation kinetics.