Photocatalytic H₂ O₂ Generation Reaction with a Benchmark Rate at Air-Liquid-Solid Joint Interfaces

Area of Science:

• Materials Science
• Photocatalysis
• Green Chemistry

Background:

• Photocatalytic hydrogen peroxide (H₂O₂) generation faces challenges including rapid charge recombination, poor selectivity in the two-electron oxygen reduction reaction (ORR), and slow O₂ diffusion.
• These limitations hinder the practical application of H₂O₂ production systems.

Purpose of the Study:

• To develop an efficient and sustainable photocatalytic system for H₂O₂ generation.
• To overcome the limitations of conventional systems by utilizing a triphase (air-liquid-solid) interface.

Main Methods:

• Fabrication of modified polymeric carbon nitride (PCN) materials incorporating pyrrole units and cyano groups.
• Implementation of a triphase photocatalytic system for H₂O₂ generation at the joint interfaces.
• Investigation of oxygen molecule activation, charge carrier separation, and O₂ diffusion dynamics using simulations and electrochemical tests.

Main Results:

• The modified PCN demonstrated enhanced activation of oxygen molecules and improved spatial separation of HOMO and LUMO orbits, leading to efficient charge carrier separation.
• The triphase system significantly improved O₂ transport to the reaction interface, overcoming solubility and diffusion limitations.
• A benchmark H₂O₂ generation rate of 2063.21 µmol g⁻¹ h⁻¹ was achieved, a tenfold increase compared to traditional powder photocatalysts (215.44 µmol g⁻¹ h⁻¹).

Conclusions:

• The developed triphase photocatalytic system offers a promising strategy for efficient and sustainable H₂O₂ production.
• Enhanced oxygen diffusion at the triphase interface is crucial for promoting charge separation and maximizing H₂O₂ yield.
• Modification of PCN with specific functional groups further boosts photocatalytic performance.