Continuous and stable photocatalytic hydrogen peroxide production via π-π engineered microenvironments in covalent...

Hydrogen peroxide (H₂O₂) exhibits substantial potential for applications in sustainable chemistry; however, its photocatalytic synthesis in aqueous media is plagued by key challenges, including inadequate charge separation, unstable reaction intermediates, and cumbersome product recovery processes. This study introduces the benzyl alcohol (BA)-water system integrated with benzo[1,2-b:3,4-b':5,6-b"]trithiophene (BTT)-based covalent organic frameworks (COFs) to address imitations. The planar, sulfur-rich BTT unit enhances π stacking and interfacial charge separation, while the unique π-π interaction between BTT-n-COFs and BA regulates the charge distribution and optimizes the microenvironment of active sites. This configuration enables BTT-3-COF to achieve an unprecedented H₂O₂ production of 13,055 μmol g^-1 h^-1. More importantly, unlike conventional systems that necessitate catalyst recovery, the present system utilizes inherent phase separation to enable facile and continuous product extraction. Remarkably, the system sustains continuous H₂O₂ production for over 20 cycles without loss of activity, yielding a ready-to-use solution that proves effective in both inhibiting bacterial growth and degrading pollutants. Experimental and computational analyses reveal a dual-channel mechanism: spatially segregated superoxide radical (∙O₂^-, oil phase) and hydroxyl radical (∙OH, aqueous phase) synergistically drive water oxidation reaction (WOR) and oxygen reduction reaction (ORR). This work presents an innovative example for sustainable and durable photocatalytic H₂O₂ production.