Covalent Organic Frameworks Containing Dual O2 Reduction Centers for Overall Photosynthetic Hydrogen Peroxide Production.

Abstract

Covalent organic frameworks (COFs) are highly desirable for achieving high-efficiency overall photosynthesis of hydrogen peroxide (H2 O2 ) via molecular design. However, precise construction of COFs toward overall photosynthetic H2 O2 remains a great challenge. Herein, we report the crystalline s-heptazine-based COFs (HEP-TAPT-COF and HEP-TAPB-COF) with separated redox centers for efficient H2 O2 production from O2 and pure water. The spatially and orderly separated active sites in HEP-COFs can efficiently promote charge separation and enhance photocatalytic H2 O2 production. Compared with HEP-TAPB-COF, HEP-TAPT-COF exhibits higher H2 O2 production efficiency for integrating dual O2 reduction active centers of s-heptazine and triazine moieties. Accordingly, HEP-TAPT-COF bearing dual O2 reduction centers exhibits a remarkable solar-to-chemical energy efficiency of 0.65 % with a high apparent quantum efficiency of 15.35 % at 420 nm, surpassing previously reported COF-based photocatalysts.