Co₃O₄-Impregnated NiO-YSZ: An Efficient Catalyst for Direct Methane Electrooxidation

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Direct methane electrooxidation is crucial for clean energy conversion.
• Developing efficient electrocatalysts that mitigate coking is essential for practical applications.
• Nickel oxide-yttria-stabilized zirconia (NiO-YSZ) is a common anode material, but its performance can be improved.

Purpose of the Study:

• To investigate the physical and electrochemical properties of cobalt oxide (Co3O4)-impregnated NiO-YSZ as an electrocatalyst for direct methane electrooxidation.
• To compare the performance of Co3O4-impregnated NiO-YSZ with unmodified NiO-YSZ and cerium oxide (CeO2)-impregnated NiO-YSZ.
• To understand the mechanisms behind the enhanced catalytic activity and coking mitigation.

Main Methods:

• Electrochemical characterization including measurement of exchange current density (i0).
• Materials characterization using X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR).
• Microstructural analysis via high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM).

Main Results:

• Co3O4-impregnated NiO-YSZ exhibited superior methane electrooxidation activity compared to CeO2-impregnated NiO-YSZ and NiO-YSZ.
• The exchange current density (i0) trend was Co3O4-impregnated NiO-YSZ (88 mA cm-2) > CeO2-impregnated NiO-YSZ (83 mA cm-2) > NiO-YSZ (2 mA cm-2).
• Co3O4-impregnated NiO-YSZ showed significantly reduced coking during operation.

Conclusions:

• The enhanced activity of Co3O4-impregnated NiO-YSZ is attributed to modifications in electronic structure and microstructure, including nickel incorporation into the Co3O4 lattice.
• Co3O4-impregnated NiO-YSZ is a promising electrocatalyst for direct methane electrooxidation, offering high activity and coking resistance.
• Further research into the fundamental properties of these modified anodes could lead to improved solid oxide fuel cell technologies.