Engineering Localized Alkalinity and Oxygen Enrichment for Efficient Acidic O₂-to-H₂O₂ Electroreduction via...

Area of Science:

• Electrochemistry
• Materials Science
• Sustainable Chemistry

Background:

• The anthraquinone process for hydrogen peroxide (H2O2) production is energy-intensive.
• The two-electron oxygen reduction reaction (2e⁻ ORR) is a promising sustainable alternative but suffers from slow kinetics in acidic media.

Purpose of the Study:

• To develop a novel air diffusion electrode (ADE) for efficient and sustainable H2O2 electrosynthesis.
• To overcome the kinetic limitations of the 2e⁻ ORR in acidic conditions.

Main Methods:

• Engineering a needle-shaped hydrophobic carbon felt embedded with hard carbon to act as a natural ADE.
• Utilizing in situ and ex situ characterization techniques to analyze the electrode's microenvironment and performance.
• Performing density functional theory (DFT) calculations to understand the catalytic mechanism.

Main Results:

• The designed ADE creates an oxygen-enriched, locally alkaline microenvironment, accelerating 2e⁻ ORR kinetics.
• Achieved 95.47% H2O2 selectivity at near-zero overpotential and a production rate of 487.82 mg L⁻¹ h⁻¹ at 200 mA cm⁻².
• DFT calculations confirmed the role of carboxyl and ether groups in optimizing O2 adsorption for the 2e⁻ pathway.

Conclusions:

• The developed ADE demonstrates exceptional performance, stability, and a reduced global warming potential compared to conventional methods.
• This strategy offers a viable pathway for revolutionizing industrial-scale H2O2 electrosynthesis.
• The novel ADE design shows potential to replace commercial carbon black-based cathodes.