Dual Metal‐Bridged 2D COF for High Performance of H ₂ O ₂ Photosynthesis Across Wide pH Range Activated by Dual Route Linkage

Abstract

ABSTRACT Successfully converting water and oxygen into H 2 O 2 by covalent organic frameworks (COFs) suffers from strong pH dependence in generally used photocatalysis process. Herein, we created a dual metal‐bridged 2D COF by using Co and Mn as bridging atom sites axial coordinated with layered TAPB‐BTCA‐COF. Mn sites function as water splitting and oxidation centers, enabling an in situ proton feeding process to drive the kinetically favorable *OO hydrogenation reaction on Co sites. Such a dual route linkage effectively alleviates the proton‐transfer limitation in 2e − ORR reactivity. The d ‐π conjugated structure created by the axial coordinated bridging metal sites in the COF framework speeds up the separation of photogenerated electron‐hole pairs. Subsequently, this catalyst performed outstanding and stable photocatalytic H 2 O 2 production rate across a broad pH range benefiting this dual route linkage including indirect 2e − ORR process and WOR process. Specifically, in a gas–liquid–solid triple‐phase photocatalytic reaction system composed of water and cinnamyl alcohol (COL), the H 2 O 2 production rate of Co2Mn1‐COF reached 3664.37 µmol g − 1 h − 1 , with a quantum yield (AQY) of 8.6% under visible light irradiation, almost four times higher than that of unmodified COF. Meanwhile, COL can simultaneously be highly selectively converted into the additional value‐added compounds cinnamonaldehyde and cinnamonmic acid.