Engineering non-uniform π-delocalization in donor units of covalent organic frameworks for enhanced photocatalytic H2O2 generation

In process of catalyzing two-electron oxygen reduction to produce hydrogen peroxide (H 2 O 2 ) within covalent organic frameworks (COFs), charge separation capability and transport efficiency are critical factors. The study has designed two COFs (TAPT-BT COF and TAPB-BT COF) in order to investigate influence of unevenly delocalized π electrons within conjugated system in donor units to photocatalytic production of H 2 O 2 . The incorporation of triazine rings into TAPT-BT COF enables material to achieve H 2 O 2 production rate of up to 2471.53 μmol g −1 h −1 when benzyl alcohol is used as sacrificial agent, which is 5.18 times higher than TAPB-BT COF. Experimental evidence demonstrates that the introduction of triazine ring successfully enhances carrier separation and transport efficiency within COFs, simultaneously reduces reaction energy barriers for intermediates *O − 2 and *OOH. From kinetic perspective, triazine ring also amplifies photocatalytic activity of COFs. This work elucidates impact of non-uniform delocalization of π electrons in donor units on H 2 O 2 photocatalytic performance of COFs, and provides novel design strategies for enhancing yield of photocatalytic H 2 O 2 production from materials.