Regulating exciton generation and transfer upon nanoarchitectonics with carbon nitrogen polymer for photocatalytic hydrogen peroxide evolution coupled with ethanol selective oxidation

Abstract

Efficient generation and rapid transfer of photogenerated carriers are crucial for the improvement of photocatalytic reaction. Herein, pyromellitic anhydride as electron acceptor is embedded into porous g-C₃N₄ for constructing D-A polymer (namely P-g–C₃N₄–Pa). The introduction of pyromellitic anhydride effectively improves π→π∗ and n→π∗ electronic transitions, enhancing light utilization efficiency. Significant potential difference between pyromellitic anhydride and g-C₃N₄ weakens excitonic effect to produce free electrons and holes. Thus, P-g–C₃N₄–Pa exhibits excellent performance in photocatalytic H₂O₂ synthesis. In-situ spectroscopy and electrochemical tests reveal that two-electron oxygen reduction reaction is major pathway, and O₂^•‒ is a key intermediate. Embedded pyromellitic anhydride also boosts capture capability of g-C₃N₄ for O₂, thereby overcoming rate-limiting step to promote ∗O₂ generation. Furthermore, photogenerated holes located on g-C₃N₄ can selectively oxidize ethanol to produce acetaldehyde with high economic value, and generated proton facilitates H₂O₂ generation. Importantly, the highest yield of H₂O₂ is 5600.8 μmol g⁻¹•h⁻¹ over P-g–C₃N₄–Pa under visible light irradiation in the presence of ethanol.