Oligo(phenylenevinylene)-Based Covalent Organic Frameworks with Kagome Lattice for Boosting Photocatalytic Hydrogen Evolution.

Abstract

Covalent organic frameworks (COFs) have shown great advantages as photocatalysts for hydrogen evolution. However, the effect of linkage geometry and type of linkage on the extent of π-electron conjugation in the plane of the framework and photocatalytic properties of COFs remains a significant challenge. Herein, two Kagome (kgm) topologic oligo(phenylenevinylene)-based COFs are designed and synthesized for boosting photocatalytic hydrogen evolution via a "two in one" strategy. Under visible light irradiation, COF-954 with 5 wt% Pt as cocatalyst exhibits high hydrogen evolution rate (HER) of 137.23mmol g-1 h-1 , outperforming most reported COF-based photocatalysts. More importantly, even in natural seawater, COF-954 shows an average HER of 191.70mmol g-1 h-1 under ultraviolet-visible (UV-vis) light irradiation. Additionally, the water-drainage experiments indoors and outdoors demonstrate that 25 and 8mL hydrogen gas could be produced in 80 min under UV-vis light and natural sunlight, respectively, corresponding to a high HER of 167.41 and 53.57mmol h-1 g-1 . This work not only demonstrates an effective design strategy toward highly efficient COF-based photocatalysts, but also shows the great potential of using the COF-based photocatalysts for photocatalytic hydrogen evolution.