Reducing Oxygen Evolution Reaction Overpotential in Cobalt-Based Electrocatalysts via Optimizing the...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Sluggish kinetics in multielectron transfer hinder efficient oxygen evolution reaction (OER) activity.
• Reducing reaction overpotential is critical for boosting OER kinetics.
• Cobalt-based materials are promising electrocatalysts, but their performance needs optimization.

Purpose of the Study:

• To investigate the correlation between OER overpotential and cobalt-based electrode composition in a novel "Microparticles-in-Spider Web" (MSW) superstructure.
• To optimize electrode configuration for enhanced electrocatalytic activity and reduced overpotential.
• To provide a general strategy for improving OER kinetics through electrode design.

Main Methods:

• Fabrication of cobalt-based composite electrodes with a "Microparticles-in-Spider Web" (MSW) superstructure.
• Systematic variation of the Co/Co3O4 ratio within the composite electrode.
• Electrochemical characterization including overpotential measurements at a current density of 10.0 mA cm-2 in alkaline conditions.
• Analysis of electrochemically active surface area and charge-transfer resistance.
• Theoretical calculations (e.g., DFT) to understand catalytic mechanisms.

Main Results:

• A clear correlation was found between OER overpotential and the Co/Co3O4 ratio in the MSW electrode.
• The optimized electrode exhibited a dramatically decreased overpotential, reaching 260 mV at 10.0 mA cm-2.
• The optimized electrode demonstrated long-term stability, comparable or superior to existing Co-based OER electrocatalysts.
• Electrochemical active surface area and charge-transfer resistance were identified as key factors influenced by electrode composition.

Conclusions:

• Optimizing the Co/Co3O4 ratio in the MSW superstructure is an effective strategy to mitigate OER overpotential.
• The MSW superstructure enhances electrochemically active sites and electron transfer, leading to remarkable catalytic activity.
• Metallic Co and Co3O4 sites play crucial roles in electron transport and reducing Gibbs free energies, respectively.
• This study offers a general approach to boost OER kinetics by optimizing electrode configurations for reduced overpotential.