Self-Supporting Co/CeO₂ Heterostructures for Ampere-Level Current Density Alkaline Water Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Heterostructures enhance alkaline water electrolysis for renewable energy.
• Challenges remain in synthesizing reactive and robust electrodes for high-current density hydrogen evolution (HER) and oxygen evolution (OER).

Purpose of the Study:

• To develop a novel Co/CeO2 heterojunction self-supported electrode for sustainable overall water splitting.
• To achieve high performance in both HER and OER at ampere-level current densities.

Main Methods:

• Fabrication of Co/CeO2 heterostructures.
• Electrochemical characterization including overpotential measurements for HER and OER at various current densities.
• Density functional theory (DFT) calculations to understand active sites and charge redistribution.
• Assembly of an electrolyzer using the self-supporting electrode for overall water splitting.

Main Results:

• The Co/CeO2 heterostructures exhibited low overpotentials for HER (31.9 mV at 0.01 A·cm-2) and OER (214.1 mV at 0.01 A·cm-2).
• The electrode achieved excellent bifunctional performance, comparable to leading Co-based electrodes.
• An electrolyzer using this electrode required a low cell voltage of 1.92 V at 1.0 A·cm-2 for overall water splitting.
• DFT calculations revealed optimized adsorption sites at the heterointerfaces for reaction intermediates.

Conclusions:

• The developed Co/CeO2 heterojunction electrode is highly effective and robust for overall water splitting.
• The self-supporting nature and optimized interfaces contribute to efficient hydrogen production.
• This work highlights the potential of self-supporting heterostructures for cost-effective and sustainable energy solutions.