A motif for B/O-site modulation in LaFeO₃ towards boosted oxygen evolution

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Perovskite oxides are promising electrocatalysts for water oxidation.
• Optimizing their electronic structure is crucial for enhancing catalytic activity.
• Traditional doping strategies face limitations in improving oxygen evolution reaction (OER) performance.

Purpose of the Study:

• To synthesize and characterize transition metal (Ni) doped iron-based perovskite oxides (LaFe _1-xNi _xO _3-δ).
• To investigate the effect of non-metallic element (N) co-doping on the OER performance of optimized perovskite oxides.
• To elucidate the underlying mechanisms of co-doping on catalytic activity and stability.

Main Methods:

• Synthesis of a series of LaFe _1-xNi _xO _3-δ perovskite oxides with varying Ni content (x = 0, 0.25, 0.5, 0.75, 1).
• Co-doping of the optimized Ni-Fe ratio perovskite oxide with nitrogen (N).
• Experimental and theoretical investigations including electrochemical measurements (overpotential, Tafel slope) and analysis of adsorption energies.

Main Results:

• Co-doping successfully broke the traditional linear constraint relationship (G_OOH - G_OH = 3.2 eV).
• Theoretical overvoltage was reduced from 0.64 V (LaFeO _3-δ) to 0.44 V (LaFe _0.5Ni _0.5O _3-δ/N).
• The optimized LaFe _0.5Ni _0.5O _3-δ/N exhibited a low overpotential of 270.6 mV at 10 mA cm^-2 and a Tafel slope of 65 mV dec^-1, outperforming LaFeO _3-δ and IrO ₂.
• The co-doped material demonstrated good durability over a 35 h stability test.

Conclusions:

• Nickel and nitrogen co-doping significantly enhances the oxygen evolution reaction (OER) performance of perovskite oxides.
• Ni-doping improves electron transfer and conductivity, while N-doping optimizes adsorption energies for key intermediates.
• This cation and anion co-doping strategy provides a new avenue for designing efficient and stable perovskite-based electrocatalysts for sustainable energy applications.