Metallic Inverse Opal Frameworks as Catalyst Supports for High-Performance Water Electrooxidation

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Oxygen evolution reaction (OER) catalysts often suffer from low electrical conductivity, limiting their intrinsic activity.
• Nickel-iron layered double hydroxides (NiFe LDH) are highly active OER catalysts but exhibit poor conductivity.

Purpose of the Study:

• To develop a highly conductive support for active OER catalysts.
• To improve the overall efficiency of oxygen evolution through enhanced conductivity and surface area.

Main Methods:

• Fabrication of copper inverse opal (IO) frameworks as porous, conductive supports.
• Coating NiFe LDH onto the copper IO structures.
• Electrochemical testing of the composite catalyst in 1 M KOH.

Main Results:

• The NiFe LDH/Cu IO composite demonstrated significantly higher OER activity compared to unsupported NiFe LDH or NiFe LDH on flat substrates.
• Achieved oxygen evolution rates of 100 mA cm^-2 (727±4 A g_catalyst^-1) at an overpotential of 0.305±0.003 V.
• The catalyst exhibited a low Tafel slope of 0.044±0.002 V dec^-1 with thin catalyst layers (2.2±0.4 μm).

Conclusions:

• Copper inverse opals provide an effective high-surface-area, conductive support for active but poorly conducting OER catalysts like NiFe LDH.
• The developed composite catalyst shows promise for application in membrane electrolyzers due to its high performance and thin catalyst layer.