Activated carbon filled in a microporous titanium-foam air diffusion electrode for boosting H₂O₂ accumulation

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Engineering

Background:

• The electro-Fenton process for pollutant degradation suffers from low hydrogen peroxide (H₂O₂) generation due to poor oxygen mass transfer and oxygen reduction reaction (ORR) selectivity.
• Existing methods often struggle to efficiently supply oxygen and facilitate the ORR for effective H₂O₂ synthesis.

Purpose of the Study:

• To develop a novel gas diffusion electrode (GDE) for enhanced H₂O₂ generation in the electro-Fenton process.
• To investigate the impact of activated carbon particle size and integration with a titanium-foam substrate on electrode performance.

Main Methods:

• Fabrication of activated carbon-filled titanium-foam gas diffusion electrodes (AC@Ti-F GDE) with varying AC particle sizes (850 μm, 150 μm, 75 μm).
• Electrochemical characterization and performance evaluation of the fabricated GDEs in an electro-Fenton system.
• Analysis of H₂O₂ generation, dissolved oxygen levels, ORR selectivity, and electron transfer efficiency.

Main Results:

• The AC@Ti-F GDE demonstrated a significant 176.15% improvement in H₂O₂ formation compared to conventional electrodes.
• The 850 μm AC particle size yielded the highest H₂O₂ accumulation (1487 μM in 2 hours) due to optimized gas-liquid-solid interfaces and dissolved oxygen.
• Achieved high H₂O₂ selectivity (96.79%) and electron transfer (2.12) during ORR, balancing H₂O₂ formation and decomposition.

Conclusions:

• The facile AC@Ti-F GDE configuration is highly promising for efficient H₂O₂ accumulation in electro-Fenton applications.
• Optimizing activated carbon particle size and electrode structure is crucial for enhancing mass transfer and ORR selectivity.
• This approach offers a viable strategy for improving H₂O₂ generation efficiency in electrochemical water treatment.