Rational Construction of Cyanide-Functionalized D-A-π-D Covalent Organic Framework for Highly Efficient Overall H2O2 Photosynthesis from Air and Water.

ABSTRACT

Sacrificial-agent-free overall photosynthesis of H2O2 from water and air represents currently a promising route to reform the industrial anthraquinone production manner, but, still blocks by the requirement of pure O2 feedstock, due to the insufficient oxygen supply from water under air. Herein, we report a rational molecule design on COFs (covalent organic frameworks) equiped with cyanide-functionalized D-A-π-D system for highly efficient overall H2O2 production from air and water through photocatalytic oxygen reduction reactions (ORR) and water oxidation reaction (WOR). Without using any sacrificial agent, the as-synthesized D-A-π-D COF is found to enable a H2O2 production rate as high as 4742 µmol h-1 g-1 from water and air and an O2 utilization and conversion rate up to 88%, exceeding the other D-A-π-A COF by respectively 1.9- and 1.3-fold. Such high performance is attributed to the tuned electronic structure and prolonged charge lifetime facilitated by the unique D-A-π-D structure and cyanide groups. This work highlights a fundamental molecule design on advanced photocatalytic COFs with complicated D-A system for low-cost and massive H2O2 production.