Enhanced oxygen evolution performance of iron-nickel oxide catalyst through dual-defect engineering

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Transition metal oxides are key electrocatalysts for the oxygen evolution reaction (OER).
• Oxygen vacancies (V_o) in these oxides enhance conductivity and activity but are prone to degradation during catalysis.
• This instability limits the long-term performance of transition metal oxide catalysts.

Purpose of the Study:

• To enhance the catalytic activity and stability of NiFe₂O₄ for OER.
• To investigate the effect of dual-defect engineering by filling oxygen vacancies with phosphorus.
• To understand the mechanism by which phosphorus incorporation improves catalyst performance.

Main Methods:

• Synthesis of NiFe₂O₄ with oxygen vacancies and subsequent phosphorus filling (NiFe₂O₄-V_o-P).
• Electrochemical characterization including OER performance testing (overpotentials, current densities).
• Theoretical calculations (e.g., DFT) to analyze electronic structure, conductivity, and binding energies.

Main Results:

• Phosphorus filling optimized the electronic structure and enhanced electrical conductivity of NiFe₂O₄.
• The NiFe₂O₄-V_o-P catalyst exhibited significantly improved intrinsic activity and stability.
• Achieved ultra-low OER overpotentials (234 mV at 10 mA cm^-2) and excellent durability (120 h at 100 mA cm^-2).

Conclusions:

• Dual-defect engineering by phosphorus incorporation is a viable strategy to stabilize oxygen vacancies and boost OER performance.
• The synergistic effect of phosphorus and oxygen vacancies in NiFe₂O₄ leads to highly active and stable electrocatalysts.
• This approach offers a new pathway for designing advanced transition metal oxide catalysts through precise defect control.