Cu_xO-Modified Nanoporous Cu Foil as a Self-Supporting Electrode for Supercapacitor and Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Designing nanoporous metal foils for supercapacitors and catalysis is crucial but difficult.
• Existing methods often lack efficiency or scalability.

Purpose of the Study:

• To develop a facile in situ method for growing copper oxide (CuₓO) nanoflakes on nanoporous copper (Cu) foil.
• To evaluate the performance of the resulting electrode for supercapacitor applications and oxygen evolution reaction (OER) catalysis.

Main Methods:

• A gallium (Ga)-assisted surface alloying-dealloying process was used to create a nanoporous Cu layer on a flexible Cu foil.
• Subsequent electrooxidation at a constant potential modified the nanoporous Cu layer with CuₓO nanoflakes.

Main Results:

• The optimized CuₓO/Cu electrode (O-Cu-2h) achieved a maximum areal capacitance of 0.745 F cm⁻² (410.27 F g⁻¹) at 0.2 mA cm⁻².
• The electrode maintained 94.71% of its capacitance after 12,000 cycles.
• A supercapacitor using O-Cu-2h as the positive electrode demonstrated an energy density of 24.20 Wh kg⁻¹ and a power density of 0.65 kW kg⁻¹.
• The electrode showed potential as an oxygen evolution reaction catalyst with an overpotential of 394 mV at 10 mA cm⁻², though long-term stability requires further enhancement.

Conclusions:

• The facile electrooxidation method successfully produced CuₓO nanoflakes on nanoporous Cu foil, yielding high-performance supercapacitor electrodes.
• The developed material exhibits promising energy and power densities for supercapacitor applications.
• While showing catalytic activity for OER, further improvements in long-term stability are necessary for practical catalytic applications.